Rozprawy doktorskie na temat „CFD METHODOLOGY”

In the past two decades, a growing interest in alternative energy resources as a replacement to the non-renewable resources used now days. These alternatives include geothermal energy which can be used to generate power and reduce the demands on energy used to heat and cool buildings. Ground-coupled ventilation system is one of the many applications of the geothermal energy that have a lot of attention in the early 80â s and 90â s but all designs of the system where based on single case situations. On the other hand, computational fluid dynamics tools are used to simulate heat and fluid flow in any real life situation. They start to develop rapidly with the fast development of computers and processors. These tools provide a great opportunity to simulate and predict the outcome of most problems with minimum loss and better way to develop new designs. By using these CFD tools in GCV systems designing procedure, energy can be conserved and designs going to be improved. The main objective of this study is to find and develop a CFD modeling strategy for GCV systems. To accomplish this objective, a case study must be selected, a proper CFD tool chosen, modeling and meshing method determined, and finally running simulations and analyzing results. All factors that affect the performance of GCV should be taken under consideration in that process such as soil, backfill, and pipes thermal properties. Multiple methods of simulation were proposed and compared to determine the best modeling approach.
Master of Science

Includes bibliographical references
The flow properties, or rheology, of particulate suspensions are highly dependent on the properties of the particles suspended within the base fluid (e.g. size, shape and surface properties). An understanding of the suspension rheology can help in the prediction of its behaviour under various flow conditions. Many studies focus on the experimental measurement of suspension properties, commonly employing devices such as rheometers to measure fluid properties under different conditions. A numerical model that is able to simulate the real-world interactions that determine particulate suspension rheology would complement those experimental studies. Accordingly, this work outlines a methodology for the development of such a model. Due to the differences between the two phases in a suspension, two different numerical methods were used, namely Computational Fluid Dynamics (CFD) and the Discrete Element Method (DEM). CFD uses a continuum approach to model the fluid component, while DEM resolves the behaviour of each individual particle. Two separate software programmes were used. For CFD, Open FOAM® was chosen, and for DEM, a programme called LIGGGHTS was used. These two different codes were coupled together with another programme called CFDEM. All three packages are open source software. To measure the rheology of the mixture, it was decided to simulate a rheometer. In particular, a rate-controlled, concentric-cylinder arrangement was chosen. Flow would be driven by a moving inner wall. Particle surface charge was accounted for by including both the van der Waals and electrostatic long-range forces between particles. This combination is known as the DLVO force. Plain particles, with no DLVO forces, were also considered. To the author's knowledge, using a coupled CFD-DEM approach to model suspension rheology had never been attempted before. Therefore, it was decided the development of the model would be done in stages, adding more complexity as each stage proved successful. The first step was to model a reduced rheometer geometry using CFD. Both a Newtonian and a non-Newtonian single-phase fluid were tested. Water and a Herschel-Bulkley mineral slurry were used respectively. Different rheometer geometries were tested. Results from these models correlated well with experimental values. The single-gap rheometer geometry with a 500μm gap between the inner and outer walls was found to perform the best. Final CFD model parameters used in these simulations were used as the basis for the coupled model. To reduce computational complexity, the model size and shape had to be reduced from a full-sized rheometer to that of a small rectangular box, with opposing flat walls acting as inner and outer cylinders of a rheometer. This improved computational efficiency. CFD tests conducted on the new box geometry showed that a box with sides of length 50μmproduced results equivalent to larger, full-sized, single-gap rheometer geometries with curved walls.

In this work, a Computational Fluid Dynamic methodology for the simulation of the charge formation process in Gasoline Direct Injection engines is presented. The aim of the work is to develop a methodology suitable in an industrial environment to drive and support the development process of modern GDI engines. A big emphasis is placed on the comparison of the proposed CFD models with experimental data obtained using a single-cylinder optical engine. Chapter 1 describes the working context and sets the aim of the work. After a brief recall of the theoretical background of CFD in chapter 2, an overview of the optical techniques interesting for Internal Combustion Engine applications is presented in chapter 3, and the basic principles of spray atomization theory are reviewed in chapter 4. In chapter 5 the CFD simulations for the charge motion in-cylinder are described. Two different engines were investigated, and the effect of different turbulence models and numerical schemes are analyzed, comparing the results with optical experimental data. The standard k-eps model, together with the MARS numerical scheme, showed the better capability to reproduce the charge motion and turbulence pattern in-cylinder, and therefore they were used for the remaining part of the work. In chapter 7 the injection model used is discussed. Despite a traditional Lagrangian-Eulerian approach, the model presents an innovative procedure capable to reproduce also the liquid core. After that the effects of the use of the liquid core and a bi-component fuel are analyzed, the in-cylinder injection results for the two investigated engines are presented. The injection model shows its capability to correctly reproduce the spray shape and penetration in different operating conditions and for different injector types, using a reduced amount of calibration parameters. Finally, chapter 8 presents some "diagnostic indexes" capable to resume the results of the CFD simulations in a reduced number of parameters. In particular, some indexes to assess the quality of the mixture and the wall impingement tendency are proposed, allowing to use the CFD simulations to address these crucial aspects in the choice of injector targeting and actuation strategy. The proposed methodology allows to use CFD simulations to support the engine development process, and was successfully applied to many different spark ignited engines.

A Computational Fluid Dynamics/Computational Fluid Dynamics (CFD/CSD) coupling interface was developed to obtain aeroelastic solutions of a morphing rotor. The methodology was implemented in Fully Unstructured Navier-Stokes (FUN3D) solver, which communicates aerodynamic forces on the blade surface to University of Michigan’s Nonlinear Active Beam Solver (UM/NLABS) and then imports structural deflections of the blade surface during each time step. Development of this methodology adds the capability to model elastic rotors with flexible airfoils. The method was validated through an aerodynamic work analysis, comparison of sectional blade loads and deflections with experimental data, and two-dimensional stability analyses for pitch/plunge flutter and camber flutter. Computational simulations were performed for a rotor in forward flight with the CFD/CSD solver and with a comprehensive CSD solver using finite-state (F-S) aerodynamics, and results were compared. Prescribed three-per-revolution camber deflections were then applied, and solutions of the CFD/CSD and comprehensive CSD computations indicated that three-per-revolution camber actuation has the potential to minimize hub forces and moments with deflections as small as 0.25%c. In anticipation of active rotor experiments inside enclosed facilities, the capability of CFD for accurately simulating flow inside enclosed volumes was examined. It was determined that URANS models are not suitable for rotor simulations in an enclosed facility, and components that are a distance of two to three rotor radii from the hub were also observed to have a large influence on recirculation and performance.

This dissertation presents a methodology to simulate the dispersion of water droplets in the air flow typical of an Icing Tunnel. It is based on the understanding the physical parameters that influence the uniformity and the distribution of cloud of droplets in the airflow and to connect them with analytical parameters which may be used to describe the dispersion process. Specifically it investigates the main geometrical and physical parameters contributing to the droplets dispersion at different tunnel operative conditions, finding a consistent numerical approach to reproduce the local droplets dynamic, quantifying the possible limits of commercial CFD methods, pulling out the empirical parameters/constant needing to simulate properly the local conditions and validating the results with calibrated experiment. An overview of the turbulence and multiphase flow theories, considered relevant to the Icing Tunnel environment, is presented as well as basic concepts and terminology of particle dispersion. Taylor’s theory of particle dispersion has been taken as starting point to explain further historical development of discrete phase dispersion. Common methods incorporated in commercial CFD software are explained and relative shortcomings underlined. The local aerodynamic condition within tunnel, which are required to perform the calculation with the Lagrangian particle equation of motions, are generated numerically using different turbulent models and are compared to the historical K-ε model. Verification of the calculation is performed with grid independency studies. Stochastic Separated Flow methods are applied to compute the particle trajectories. The Discrete Random Walk, as described in the literature, has been used to perform particle dispersion analysis. Numerical settings in the code are related to the characteristics of the local turbulent condition such as turbulence intensity and length scales. Cont/d.

Combustion instabilities (thermo-acoustic pressure oscillations) have been recognised for some time as a problem limiting the development of low emissions (e.g., lean burn) gas turbine combustion systems, particularly for aviation propulsion applications. Recently, significant research efforts have been focused on acoustic damping for suppression of combustion instability. Most of this work has either been experimental or based on linear acoustic theory. The last 3-5 years has seen application of density based CFD methods to this problem, but no attempts to use pressure-based CFD methods which are much more commonly used in combustion predictions. The goal of the present work is therefore to develop a pressure-based CFD algorithm in order to predict accurately acoustic propagation and acoustic damping processes, as relevant to gas turbine combustors. The developed computational algorithm described in this thesis is based on the classical pressure-correction approach, which was modified to allow fluid density variation as a function of pressure in order to simulate acoustic phenomena, which are fundamentally compressible in nature. The fact that the overall flow Mach number of relevance was likely to be low ( mildly compressible flow) also influenced the chosen methodology. For accurate capture of acoustic wave propagation at minimum grid resolution and avoiding excessive numerical smearing/dispersion, a fifth order accurate Weighted Essentially Non-Oscillatory scheme (WENO) was introduced. Characteristic-based boundary conditions were incorporated to enable accurate representation of acoustic excitation (e.g. via a loudspeaker or siren) as well as enable precise evaluation of acoustic reflection and transmission coefficients. The new methodology was first validated against simple (1D and 2D) but well proven test cases for wave propagation and demonstrated low numerical diffusion/dispersion. The proper incorporation of Characteristic-based boundary conditions was validated by comparison against classical linear acoustic analysis of acoustic and entropy waves in quasi-1D variable area duct flows. The developed method was then applied to the prediction of experimental measurements of the acoustic absorption coefficient for a single round orifice flow. Excellent agreement with experimental data was obtained in both linear and non-linear regimes. Analysis of predicted flow fields both with and without bias flow showed that non-linear acoustic behavior occurred when flow reversal begins inside the orifice. Finally, the method was applied to study acoustic excitation of combustor external aerodynamics using a pre-diffuser/dump diffuser geometry previously studied experimentally at Loughborough University and showed the significance of boundary conditions and shear layer instability to produce a sustained pressure fluctuation in the external aerodynamics.

Lo sviluppo di sistemi di abbattimento compatti in grado di ridurre sia NOx che SOx è di forte interesse, per la difficoltà di combinare su una nave sia sistemi di riduzione catalitica selettiva che tecnologie di scrubber. Quindi, la ricerca sviluppata in questa tesi nasce dalla necessità di integrazione del sistema lungo la linea di scarico per risparmiare spazio e dalla necessità di disporre di un modello numerico adeguato per simulare le proprietà acustiche dei sistemi di depurazione dei gas di scarico per la loro ottimizzazione. L'obiettivo di questa tesi è sviluppare una metodologia numerica efficiente dal punto di vista computazionale che utilizzi una combinazione di simulazioni CFD e FEM, per consentire lo studio e l'ottimizzazione delle proprietà acustiche dei componenti della linea di scarico, rispettando i limiti imposti sia ai parametri geometrici che alle caratteristiche del flusso dalle reazioni chimiche necessarie per soddisfare le normative NOx e SOx. Sono stati eseguiti alcuni studi preliminari per ottimizzare l’onere computazionale delle simulazioni numeriche. Inoltre, sono state eseguite misurazioni sperimentali, sia su un set-up semplificato (tubo di impedenza) sia su un mockup di una linea di scarico di un Genset marino, al fine di valutare i risultati numerici. Le simulazioni CFD e FEM validate sono poi utilizzate per l'approccio combinato che, in primo luogo, calcola il campo di flusso (velocità e temperatura) con una simulazione CFD in regime stazionario e, poi, importa questo campo nel modello acustico FEM tramite il mesh mapping per valutare la trnsmission loss della geometria studiata in presenza di flusso. L'approccio combinato è stato quindi utilizzato per valutare e modellare le proprietà acustiche sia del catalizzatore di ossidazione diesel che dello scrubber costruiti per il Genset. La loro transmission loss raggiunge valori fino a 60 dB, permettendo di eliminare il silenziatore tradizionale, riducendo così l'ingombro della linea di scarico.
The development of compact abatement systems capable of reducing both NOx and SOx is of strong interest, due to the difficulty of combining both selective catalytic reduction systems and scrubber technologies on a ship. So, the research developed in this thesis comes from the need for system integration along the exhaust line to save space and the need to have a proper numerical model to simulate the acoustic properties of exhaust gas cleaning systems for their optimization. The objective of this thesis is to develop a computationally-efficient numerical methodology employing a combination of both CFD and FEM simulations, to allow the investigation and optimization of acoustic properties of exhaust line components, while respecting the limits imposed on both geometrical parameters and flow characteristics by the chemical reactions needed to satisfy NOx and SOx regulations. Some preliminary studies are performed to optimize computational effort of numerical simulations. Moreover, experimental measurements are performed on both a simplified set-up (impedance tube) and a mockup of a marine Genset exhaust line in order to assess the numerical results. The assessed CFD and FEM simulations are used for the combined approach that, firstly, calculates the flow field (velocity and temperature) with a steady-state CFD simulation and, then, imports this field into the acoustic FEM model through mesh mapping to evaluate the transmission loss of the studied geometry in presence of flow. The combined approach is then used on real systems, to assess and model the acoustics properties of both diesel oxidation catalyst and scrubber constructed for a Genset mockup. Their transmission loss reach values up to 60 dB, which allows elimination of the traditional silencer, thus reducing the overall dimensions.

Modern helicopters, civilian and military alike, are expected to operate in all weather conditions. Ice accretion adversely affects the availability, affordability, safety and survivability. Availability of the vehicle may be compromised if the ice formation requires excessive torque to overcome the drag needed to operate the rotor. Affordability is affected by the power requirements and cost of ownership of the deicing systems needed to safely operate the vehicle. Equipment of the rotor blades with built-in heaters greatly increases the cost of the helicopter and places further demands on the engine. The safety of the vehicle is also compromised due to ice shedding events, and the onset of abrupt, unexpected stall phenomena attributable to ice formation. Given the importance of understanding the effects of icing on aircraft performance and certification, considerable work has been done on the development of analytical and empirical tools, accompanied by high quality wind tunnel and flight test data. In this work, numerical studies to improve ice growth modeling have been done by reducing limitations and empiricism inherent in existing ice accretion models. In order to overcome the weakness of Lagrangian approach in unsteady problem such as rotating blades, a water droplet solver based on 3-D Eulerian method is developed and integrated into existing CFD solver. Also, the differences between the industry standard ice accretion analyses such as LEWICE and the ice accretion models based on the extended Messinger model are investigated through a number of 2-D airfoil and 3-D rotor blade ice accretion studies. The developed ice accretion module based on 3-D Eulerian water droplet method and the extended Messinger model is also coupled with an existing empirical ice shedding model. A series of progressively challenging simulations have been carried out. These include ability of the solvers to model airloads over an airfoil with a prescribed/simulated ice shape, collection efficiency modeling, ice growth, ice shedding, de-icing modeling, and assessment of the degradation of airfoil or rotor performance associated with the ice formation. While these numerical simulation results are encouraging, much additional work remains in modeling detailed physics important to rotorcraft icing phenomena. Despite these difficulties, progress in assessing helicopter ice accretion has been made and tools for initial analyses have been developed.Modern helicopters, civilian and military alike, are expected to operate in all weather conditions. Ice accretion adversely affects the availability, affordability, safety and survivability. Availability of the vehicle may be compromised if the ice formation requires excessive torque to overcome the drag needed to operate the rotor. Affordability is affected by the power requirements and cost of ownership of the deicing systems needed to safely operate the vehicle. Equipment of the rotor blades with built-in heaters greatly increases the cost of the helicopter and places further demands on the engine. The safety of the vehicle is also compromised due to ice shedding events, and the onset of abrupt, unexpected stall phenomena attributable to ice formation. Given the importance of understanding the effects of icing on aircraft performance and certification, considerable work has been done on the development of analytical and empirical tools, accompanied by high quality wind tunnel and flight test data. In this work, numerical studies to improve ice growth modeling have been done by reducing limitations and empiricism inherent in existing ice accretion models. In order to overcome the weakness of Lagrangian approach in unsteady problem such as rotating blades, a water droplet solver based on 3-D Eulerian method is developed and integrated into existing CFD solver. Also, the differences between the industry standard ice accretion analyses such as LEWICE and the ice accretion models based on the extended Messinger model are investigated through a number of 2-D airfoil and 3-D rotor blade ice accretion studies. The developed ice accretion module based on 3-D Eulerian water droplet method and the extended Messinger model is also coupled with an existing empirical ice shedding model. A series of progressively challenging simulations have been carried out. These include ability of the solvers to model airloads over an airfoil with a prescribed/simulated ice shape, collection efficiency modeling, ice growth, ice shedding, de-icing modeling, and assessment of the degradation of airfoil or rotor performance associated with the ice formation. While these numerical simulation results are encouraging, much additional work remains in modeling detailed physics important to rotorcraft icing phenomena. Despite these difficulties, progress in assessing helicopter ice accretion has been made and tools for initial analyses have been developed.

Computational fluid dynamics and heat transfer (CFD/HT) models have been employed as the dominant technique for the design and optimization of both new and existing data centers. Inviscid modeling has shown great speed advantages over the full Navier-Stokes CFD/HT models (over 20 times faster), but is incapable of capturing the physics in the viscous regions of the domain. A coupled inviscid-viscous solution method (CIVSM) for bounded domains has been developed in order to increase both the solution speed and accuracy of CFD/HT models. The methodology consists of an iterative solution technique that divides the full domain into multiple regions consisting of at least one set of viscous, inviscid, and interface regions. The full steady, Reynolds-Averaged Navier-Stokes (RANS) equations with turbulence modeling are used to solve the viscous domain, while the inviscid domain is solved using the Euler equations. By combining the increased speed of the inviscid solver in the inviscid regions, along with the viscous solver’s ability to capture the turbulent flow physics in the viscous regions, a faster and potentially more accurate solution can be obtained for bounded domains that contain inviscid regions which encompass more than half of the domain, such as data centers.

Axial compressors are widely used in many aerodynamic applications. The design of an axial compressor configuration presents many challenges. Until recently, compressor design was done using 2-D viscous flow analyses that solve the flow field around cascades or in meridional planes or 3-D inviscid analyses. With the advent of modern computational methods it is now possible to analyze the 3-D viscous flow and accurately predict the performance of 3-D multistage compressors. It is necessary to retool the design methodologies to take advantage of the improved accuracy and physical fidelity of these advanced methods. In this study, a first-principles based multi-objective technique for designing single stage compressors is described. The study accounts for stage aerodynamic characteristics, rotor-stator interactions and blade elastic deformations. A parametric representation of compressor blades that include leading and trailing edge camber line angles, thickness and camber distributions was used in this study A design of experiment approach is used to reduce the large combinations of design variables into a smaller subset. A response surface method is used to approximately map the output variables as a function of design variables. An optimized configuration is determined as the extremum of all extrema. This method has been applied to a rotor-stator stage similar to NASA Stage 35. The study has two parts: a preliminary study where a limited number of design variables were used to give an understanding of the important design variables for subsequent use, and a comprehensive application of the methodology where a larger, more complete set of design variables are used. The extended methodology also attempts to minimize the acoustic fluctuations at the rotor-stator interface by considering a rotor-wake influence coefficient (RWIC). Results presented include performance map calculations at design and off-design speed along with a detailed visualization of the flow field at design and off-design conditions. The present methodology provides a way to systematically screening through the plethora of design variables. By selecting the most influential design parameters and by optimizing the blade leading edge and trailing edge mean camber line angles, phenomenon s such as tip blockages, blade-to-blade shock structures and other loss mechanisms can be weakened or alleviated. It is found that these changes to the configuration can have a beneficial effect on total pressure ratio and stage adiabatic efficiency, thereby improving the performance of the axial compression system. Aeroacoustic benefits were found by minimizing the noise generating mechanisms associated with rotor wake-stator interactions. The new method presented is reliable, low time cost, and easily applicable to industry daily design optimization of turbomachinery blades.

Helicopters are versatile flying machines that have capabilities that are unparalleled by fixed wing aircraft, such as operating in hover, performing vertical take-off and landing on unprepared sites. However, modern helicopters still suffer from high levels of noise and vibration caused by the physical phenomena occurring in the vicinity of the rotor blades. Therefore, improvement in rotorcraft design to reduce the noise and vibration levels requires understanding of the underlying physical phenomena, and accurate prediction capabilities of the resulting rotorcraft aeromechanics. The goal of this research is to study the aeromechanics of rotors in steady and maneuvering flight using hybrid Computational Fluid Dynamics (CFD) methodology. The hybrid CFD methodology uses the Navier-Stokes equations to solve the flow near the blade surface but the effect of the far wake is computed through the wake model. The hybrid CFD methodology is computationally efficient and its wake modeling approach is non-dissipative making it an attractive tool to study rotorcraft aeromechanics. Several enhancements were made to the CFD methodology and it was coupled to a Computational Structural Dynamics (CSD) methodology to perform a trimmed aeroelastic analysis of a rotor in forward flight. The coupling analyses, both loose and tight were used to identify the key physical phenomena that affect rotors in different steady flight regimes. The modeling enhancements improved the airloads predictions for a variety of flight conditions. It was found that the tightly coupled method did not impact the loads significantly for steady flight conditions compared to the loosely coupled method. The coupling methodology was extended to maneuvering flight analysis and the flight test control angles were employed to enable the maneuvering flight analysis. The fully coupled model provided the presence of three dynamic stall cycles on the rotor in maneuver. Analysis of maneuvering flight requires knowledge of the pilot input control pitch settings, and the vehicle states. As the result, these computational tools cannot be used for analysis of loads in a maneuver that has not been duplicated in a real flight. This is a significant limitation if these tools are to be selected during the design phase of a helicopter where its handling qualities are evaluated in different trajectories. Therefore, a methodology was developed to couple the CFD/CSD simulation with an inverse flight mechanics simulation to perform the maneuver analysis without using the flight test control input. The methodology showed reasonable convergence in steady and maneuvering flight regimes and control angle predictions compared fairly well with test data. In the maneuvering flight regions, the convergence was slower due to relaxation techniques used for the numerical stability. Further, the enhancement of the rotor inflow computations in the inverse simulation through implementation of a Lagrangean wake model improved the convergence of the coupling methodology.

In the context of an aviation industry whose top priority is to face the sustainability challenge, the growing civil UAV branch is not an exception. Hydrogen-powered UAVs equipped with PEM (Polymer Electrolyte Membrane) fuel cells are more and more frequently identified as the most convincing and promising technology, particularly for long-endurance mission requirements. However, the onboard carriage of a hydrogen fuel cell leads to unexplored internal flow characteristics, including the introduction of water vapour. The purpose of this master thesis is to develop a valid CFD model and methodology for the internal flow simulation of hydrogen-powered UAVs. Given the strict environmental operational requirements of PEM fuel cells, the intended application of the model is to effectively assess the evolution of the internal bay flow temperature and humidity fields. An explicit-time fourth-order Runge-Kutta projection method is tested successfully on a sample 2D case setup. The case geometry and flow conditions are inspired by the Green Raven UAV project conceived by the Department of Aeronautical and Vehicle Engineering at KTH.
I samband med en flygindustri vars högsta prioritet är att bemöta hållbarhetsutma- ningen är den växande civila UAV-sektorn inget undantag. Vätgasdrivna UAV:er utrustade med PEM (Polymer Electrolyte Membrane) bränsleceller betecknas allt oftare som den mest övertygande och lovande teknologin, särskilt för att de ska kunna utföra långvariga uppdrag. Den ombordgående transporten av en vätebränslecell leder emellertid till outforskade inre flödesfenomen, inklusive alstrad vattenånga. Syftet med detta examensarbete är att utveckla en lämplig CFD-modell och metodik för intern flödesimulering av vätgasdrivna UAV. Med tanke på de strikta miljökraven för PEM-bränsleceller är modellens avsedda tillämpning att eektivt utvärdera utvecklingen av de inre flödestemperaturerna och luftfuktighetsfälten. En tidsexplicit Runge-Kutta-projektionsmetod av fjärde ordningen testas framgångsrikt på ett 2D-exempel. Fallets geometri och flödesförhållanden är inspirerade av Green Raven UAV-projektet som utförts på Farkost och Flyg avdelningen på KTH.

Com o avanço tecnológico dos computadores e o desenvolvimento de programas de simulação de fluidos, propiciando resultados cada vez mais sofisticados e eficazes, ocorreu uma redução significativa no tempo e nos custos computacionais para conceber veículos mais seguros e com menos agressão ao meio ambiente, devido ao seu menor consumo de combustível. Contudo, mesmo com o uso da Dinâmica dos Fluidos Computacional bastante disseminado, ainda são divergentes as informações sobre o nível de concordância esperado entre os resultados obtidos, por meio da simulação, quando comparada com os resultados medidos experimentalmente. Este trabalho apresenta uma sequencia metodológica para determinação das forças de arrasto sobre um veículo de transporte de pessoas (ônibus), de maneira a transmitir a compreensão dos fenômenos que envolvem o problema, a sequencia necessária de simulações e conceitos que devem ser atribuídos para obtenção de respostas coerentes. Primeiramente é abordada a análise de problemas com respostas experimentais disponíveis e assim validando a metodologia de simulação para cada parâmetro abordado, domínio, malha, discretização da camada limite e modelos de turbulência. Com base nas definições destes parâmetros são realizadas as simulações de um problema em escala real do escoamento de fluidos sobre um ônibus. A metodologia empregada para estimar os parâmetros de simulação é apresentada em forma de uma sequencia de cálculos, de fácil utilização. Os resultados demonstram que o uso do método numérico na criação de veículos pode ser ampliado, com significativa redução de ensaios experimentais. A análise numérica apresentada ratifica a metodologia numérica como importante ferramenta para aprimorar o projeto de veículos, com menor coeficiente de arrasto e maior estabilidade aerodinâmica, com isto proporcionando a redução do consumo de combustível, somados com benefícios secundários significativos, tais como, baixo acúmulo de sujeira, melhorando a visibilidade, ruído aerodinâmico reduzido e até menor fadiga do condutor.
The technological advancement of computers and the development of fluid simulation software providing results increasingly sophisticated and effective, has resulted in a significant reduction in time and computational cost to develop safer vehicles with less harm to the environment due to its lower fuel consumption. However, even with quite widespread Computational Fluid Dynamics use, there is still conflicting information on the expected level of agreement among the results obtained by simulation, when compared with the experimentally measured results. This work presents a methodological sequence to determine the drag force on a vehicle for people transportation (bus ), in order to convey the understanding of phenomena involving the problem , the required sequence of simulations, and concepts that should be assigned to obtain coherent answers. At first, one approaches the analysis of problems with available experimental answers, thus validating the simulation methodology for each parameter approached, domain , mesh ,discretization of the boundary layer and turbulence models. Based on the definitions of these parameters, simulations of an actual scale problem of fluid flow on a bus are performed. The methodology used to estimate the simulation parameters is presented in the form of a sequence of calculations easy to use. The results show that the use of the numerical method for creating vehicles can be expanded with a significant reduction in experimental tests. The numerical analysis presented confirms the numerical methodology as an important tool to upgrade the design of vehicles, with lower drag coefficient and greater aerodynamic stability, thus providing a reduction of fuel consumption, added to significant secondary benefits, such as low dirt accumulation, improving visibility, reduced aerodynamic noise and even less driver fatigue.

Orientador: Sávio Souza Venâncio Vianna
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-24T13:25:34Z (GMT). No. of bitstreams: 1 Ferreira_TatieleDalfior_M.pdf: 4562241 bytes, checksum: 69c742236e806f040cfc237f2ba91cf4 (MD5) Previous issue date: 2014
Resumo: Este trabalho tem como objetivo desenvolver um modelo matemático capaz de prever o tamanho de nuvem de gás inflamável formada em uma típica plataforma de petróleo considerando condições reais de ventilação e de operação de uma planta de processo. Para tanto, foi realizado um estudo de dispersão de gás inflamável (gás natural) na plataforma em questão utilizando Fluidodinâmica Computacional (CFD). Os resultados deste estudo de dispersão serviram como base para a construção do modelo matemático utilizando Metodologia de Superfície de Resposta. Tal modelo permite o cálculo do tamanho de nuvem de gás inflamável no ambiente estudado usando duas variáveis principais: a taxa não-dimensional de vazamento (que contabiliza a relação entre a taxa de vazamento de gás e a taxa de ventilação na plataforma) e a direção adimensional de vazamento (que computa a relação entre as direções de vazamento de gás e do vento). O modelo desenvolvido mostrou-se eficaz, pois foi capaz de prever com considerável grau de confiabilidade os tamanhos de nuvem de gás inflamável quando comparados aos valores fornecidos por simulações com CFD
Abstract: This work proposes the development of a mathematical correlation for prediction of flammable gas cloud size in a typical offshore module. Real conditions regarding the ventilation and process plant operation were considered. A dispersion study of natural gas release in the module was conducted using Computational Fluid Dynamics (CFD) and the state of art as far as the gas dispersion modelling is concerned. A mathematical model was built based on the numerical results and Response Surface Methodology (RSM). The approach comprises into a single mathematical model the most relevant independent variables. The response surface curves calculate the flammable gas cloud volume as a function of the non-dimensional leak rate (that concerns the ventilation and the gas release rate) and the non-dimensional leak direction (which comprises the wind direction and the leak direction). The developed model had proved to be effective. It was able to predict flammable gas volume and good agreement with CFD results was observed
Mestrado
Sistemas de Processos Quimicos e Informatica
Mestra em Engenharia Química

Future generation of all-electric ships will be highly dependent on electric power, since every single system aboard such as the drive propulsion, the weapon system, the communication and navigation systems will be electrically powered. Power conversion modules (PCM) will be used to transform and distribute the power as desired in various zone within the ships. As power densities increase at both components and systems-levels, high-fidelity thermal models of those PCMs are indispensable to reach high performance and energy efficient designs. Efficient systems-level thermal management requires modeling and analysis of complex turbulent fluid flow and heat transfer processes across several decades of length scales. In this thesis, a methodology for thermal modeling of complex PCM cabinets used in naval applications is offered. High fidelity computational fluid dynamics and heat transfer (CFD/HT) models are created in order to analyze the heat dissipation from the chip to the multi-cabinet level and optimize turbulent convection cooling inside the cabinet enclosure. Conventional CFD/HT modeling techniques for such complex and multi-scale systems are severely limited as a design or optimization tool. The large size of such models and the complex physics involved result in extremely slow processing time. A multi-scale approach has been developed to predict accurately the overall airflow conditions at the cabinet level as well as the airflow around components which dictates the chip temperature in details. Various models of different length scales are linked together by matching the boundary conditions. The advantage is that it allows high fidelity models at each length scale and more detailed simulations are obtained than what could have been accomplished with a single model methodology. It was found that the power cabinets under the prescribed design parameters, experience operating point airflow rates that are much lower than the design requirements. The flow is unevenly distributed through the various bays. Approximately 90 % of the cold plenum inlet flow rate goes exclusively through Bay 1 and Bay 2. Re-circulation and reverse flow are observed in regions experiencing a lack of flow motion. As a result high temperature of the air flow and consequently high component temperatures are also experienced in the upper bays of the cabinet. A proper orthogonal decomposition (POD) methodology has been performed to develop reduced-order compact models of the PCM cabinets. The reduced-order modeling approach based on POD reduces the numerical models containing 35 x 109 DOF down to less than 20 DOF, while still retaining a great accuracy. The reduced-order models developed yields prediction of the full-field 3-D cabinet within 30 seconds as opposed to the CFD/HT simulations that take more than 3 hours using a high power computer cluster. The reduced-order modeling methodology developed could be a useful tool to quickly and accurately characterize the thermal behavior of any electronics system and provides a good basis for thermal design and optimization purposes.

El trabajo presentado en esta Tesis está motivado por la necesidad de los motores de combustión interna alternativos de reducir el consumo de combustible y las emisiones de CO2 mientras se satisfacen las cada vez más restrictivas regulaciones de emisiones contaminantes. Por lo tanto, el objetivo principal de este estudio es optimizar un sistema de combustión de encendido por compresión controlado por mezcla para probar su potencial como motores de futura generación. Con esta meta se ha desarrollado un sistema automático que combina CFD con métodos de optimización avanzados para analizar y entender las configuraciones óptimas. Los resultados presentados en este trabajo se dividen en dos bloques principales. El primero corresponde a la optimización de un sistema de encendido por compresión convencional alimentado con diésel. El segundo se centra en un concepto de combustión avanzado donde se ha sustituido el fuel por Dimetil-eter. En ambos casos, el estudio no sólo halla una configuración óptima sino que también se describen las relaciones causa/efecto entre los parámetros más relevantes del sistema de combustión. El primer bloque aplica métodos de optimización no-evolutivos a un motor medium-duty alimentado por diésel tratando de minimizar consumo a la vez que se mantienen las emisiones contaminantes por debajo de los estándares de emisiones contaminantes impuestos. Una primera parte se centra en la optimización de la geometría de la cámara de combustión y el inyector. Seguidamente se extiende el estudio añadiendo los settings de renovación de la carga de y de inyección al estudio, ampliando el potencial de la optimización. El estudio demuestra el limitado potencial de mejora de consumo que tiene el motor de referencia al mantener los niveles de emisiones contaminantes. Esto demuestra la importancia de incluir parámetros de renovación de la carga e inyección al proceso de optimización. El segundo bloque aplica una metodología basada en algoritmos genéticos al diseño del sistema de combustión de un motor heavy-duty alimentado con Dimetileter. El estudio tiene dos objetivos, primero la optimización de un sistema de combustión convencional controlado por mezcla con el objetivo de lograr mejorar el consumo y reducir las emisiones contaminantes hasta niveles inferiores a los estándares US2010. Segundo la optimización de un sistema de combustión trabajando en condiciones estequiométricas acoplado con un catalizador de tres vías buscando reducir consumo y controlar las emisiones contaminantes por debajo de los estándares 2030. Ambas optimizaciones incluyen tanto la geometría como los parámetros más relevantes de renovación de la carga y de inyección. Los resultados presentan un sistema de combustión convencional óptimo con una notable mejora en rendimiento y un sistema de combustión estequiométrica que es capaz de ofrecer niveles de NOx menores al 1% de los niveles de referencia manteniendo niveles competitivos de rendimiento. Los resultados presentados en esta Tesis ofrecen una visión extendida de las ventajas y limitaciones de los motores MCCI y el camino a seguir para reducir las emisiones de futuros sistemas de combustión por debajo de los estándares establecidos. A su vez, este trabajo también demuestra el gran potencial que tiene el Dimetil-eter como combustible para futuras generaciones de motores.
The work presented in this Thesis was motivated by the needs of internal combustion engines (ICE) to decrease fuel consumption and CO2 emissions, while fulfilling the increasingly stringent pollutant emission regulations. Then, the main objective of this study is to optimize a mixing-controlled compression ignition (MCCI) combustion system to show its potential for future generation engines. For this purpose an automatic system based on CFD coupled with different optimization methods capable of optimizing a complete combustion system with a reasonable time cost was designed together with the methodology to analyze and understand the new optimum systems. The results presented in this work can be divided in two main blocks, firstly an optimization of a conventional diesel combustion system and then an optimization of a MCCI system using an alternative fuel with improved characteristics compared to diesel. Due to the methodologies used in this Thesis, not only the optimum combustion system configurations are described, but also the cause/effect relations between the most relevant inputs and outputs are identified and analyzed. The first optimization block applies non-evolutionary optimization methods in two sequential studies to optimize a medium-duty engine, minimizing the fuel consumption while fulfilling the emission limits in terms of NOx and soot. The first study targeted four optimization parameters related to the engine hardware including piston bowl geometry, injector nozzle configuration and mean swirl number. After the analysis of the results, the second study extended to six parameters, limiting the optimization of the engine hardware to the bowl geometry, but including the key air management and injection settings. The results confirmed the limited benefits, in terms of fuel consumption, with constant NOx emission achieved when optimizing the engine hardware, while keeping air management and injection settings. Thus, including air management and injection settings in the optimization is mandatory to significantly decrease the fuel consumption while keeping the emission limits. The second optimization block applies a genetic algorithm optimization methodology to the design of the combustion system of a heavy-duty Diesel engine fueled with dimethyl ether (DME). The study has two objectives, the optimization of a conventional mixing-controlled combustion system aiming to achieve US2010 targets and the optimization of a stoichiometric mixing-controlled combustion system coupled with a three way catalyst to further control NOx emissions and achieve US2030 emission standards. These optimizations include the key combustion system related hardware, bowl geometry and injection nozzle design as input factors, together with the most relevant air management and injection settings. The target of the optimizations is to improve net indicated efficiency while keeping NOx emissions, peak pressure and pressure rise rate under their corresponding target levels. Compared to the baseline engine fueled with DME, the results of the study provide an optimum conventional combustion system with a noticeable NIE improvement and an optimum stoichiometric combustion system that offers a limited NIE improvement keeping tailpipe NOx values below 1% of the original levels. The results presented in this Thesis provide an extended view of the advantages and limitations of MCCI engines and the optimization path required to achieve future emission standards with these engines. Additionally, this work showed how DME is a promising fuel for future generation engines since it is able to achieve future emission standards while maintaining diesel-like efficiency
El treball presentat en esta Tesi està motivat per la necessitat dels motors de combustió interna alternatius de reduir el consum de combustible i les emissions de CO2 mentres se satisfan les cada vegada mes restrictives regulacions d'emissions contaminants. Per tant, l'objectiu principal d'este estudi es optimitzar un sistema de combustió d'encesa per compressió controlat per mescla per a provar el seu potencial com a motors de futura generació. Amb esta meta s'ha desenrotllat un sistema automàtic que combina CFD amb mètodes d'optimització avançats per a analitzar i entendre les configuracions òptimes. Els resultats presentats en este treball es dividixen en dos blocs principals. El primer correspon a l'optimització d'un sistema d'encesa per compressió convencional alimentat amb dièsel. El segon se centra en un concepte de combustió avançat on s'ha substituït el fuel per Dimetil-eter. En ambdós casos, l'estudi no sols troba una configuració òptima sinó que també es descriuen les relacions causa/efecte entre els paràmetres més rellevants del sistema de combustió. El primer bloc aplica mètodes d'optimització no-evolutius a un motor mediumduty alimentat per dièsel tractant de minimitzar consum al mateix temps que es mantenen les emissions contaminants per davall dels estàndards d'emissions contaminants impostos. Una primera part se centra en l'optimització de la geometria de la cambra de combustió i l'injector. A continuació s'estén l'estudi afegint els settings de renovació de la càrrega de i d'injecció a l'estudi, ampliant el potencial de l'optimització. L'estudi demostra el limitat potencial de millora de consum que té el motor de referència al mantindre els nivells d'emissions contaminants. Açò demostra la importància d'incloure paràmetres de renovació de la càrrega i injecció al procés d'optimització. El segon bloc aplica una metodologia basada en algoritmes genètics al disseny del sistema de combustió d'un motor heavy-duty alimentat amb Dimetil-eter. L'estudi té dos objectius, primer l'optimització d'un sistema de combustió convencional controlat per mescla amb l'objectiu d'aconseguir millorar el consum i reduir les emissions contaminants fins nivells inferiors als estàndards US2010. Segon l'optimització d'un sistema de combustió treballant en condicions estequiomètriques acoblat amb un catalitzador de tres vies buscant reduir consum i controlar les emissions contaminants per davall dels estàndards 2030. Ambdós optimitzacions inclouen tant la geometria com els paràmetres més rellevants de renovació de la càrrega i d'injecció. Els resultats presenten un sistema de combustió convencional òptim amb una notable millora en rendiment i un sistema de combustió estequiomètrica que és capaç d'oferir nivells de NOx menors al 1% dels nivells de referència mantenint nivells competitius de rendiment. Els resultats presentats en esta Tesi oferixen una visió estesa dels avantatges i limitacions dels motors MCCI i el camï que s'ha de seguir per a reduir les emissions de futurs sistemes de combustió per davall dels estàndards establits. Al seu torn, este treball també demostra el gran potencial que té el Dimetil-eter com a combustible per a futures generacions de motors.
Hernández López, A. (2018). Optimization and analysis by CFD of mixing-controlled combustion concepts in compression ignition engines [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/103826
TESIS

El proceso de atomización desde una vena o lámina líquida hasta multitud de gotas dispersas en un medio gaseoso ha sido un fenómeno de interés desde hace varias décadas, especialmente en el campo de los motores de combustión interna alternativos. Multitud de estudios experimentales han sido publicados al respecto, pues una buena mezcla de aire-combustible asegura una evaporación y combustión mucho más eficientes, aumentando la potencia del motor y reduciendo la cantidad de contaminantes emitidos. Con el auge de las técnicas computacionales, muchos modelos han sido desarrollados para estudiar este proceso de atomización y mezcla. Uno de los últimos modelos que han aparecido es el llamado ELSA (Eulerian-Lagrangian Spray Atomization), que utiliza un modelo Euleriano para la parte densa del chorro y cambia a un modelo Lagrangiano cuando la concentración de líquido es suficientemente pequeña, aprovechando de esta manera las ventajas de ambos. En el presente trabajo se ha desarrollado un modelo puramente Euleriano para estudiar la influencia de la geometría interna de la tobera de inyección en el proceso de atomización y mezcla. Se ha estudiado únicamente el proceso de inyección diésel. Este modelo permite resolver en un único dominio el flujo interno y el externo, evitando así las comunes simplificaciones y limitaciones de la interpolación entre ambos dominios resueltos por separado. Los resultados actuales son prometedores, el modelo predice con un error aceptable la penetración del chorro, el flujo másico y de cantidad de movimiento, los perfiles de velocidad y concentración, así como otros parámetros característicos del chorro.
Martí Gómez-Aldaraví, P. (2014). DEVELOPMENT OF A COMPUTATIONAL MODEL FOR A SIMULTANEOUS SIMULATION OF INTERNAL FLOW AND SPRAY BREAK-UP OF THE DIESEL INJECTION PROCESS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/43719
TESIS
Premiado

The report describes a prestudy project for Epiroc Rock Drills AB at the department PLM Solutions. The company consists of a number of divisions thatall work with or are affected by CAD models. PLM Solutions has long seen a need for a common methodologybut due to the priorities of other projects this has been delayed. The purpose of the prestudy was to provide a mapping of the CAD methodology at the company today and also investigate the need for methodology. Based on the mapping, a recommendation was given ofhow PLM Solutions shouldproceed with a major methodology project. The recommendation wastocreate a common overall CAD methodology and take advantage of the already existing methodsin the organization. As the problem was treated as a prestudy, the method of a prestudy model is also the case. The model is general and adapted to fit this particular project. The approach deals with the phases: start-up, background analysis and solutions. The background analysis examines the current situation analysis using models for interviewing techniques. A larger part of the basis for the prestudy rests on interviews with stakeholders. The result is presented based on the same phases that the method consists of. The result is a mapping of the methodology and needs of the divisions, this is also visualized using a SWOT analysis. The results arealso the recommendation and requirements based on the interviews and business case. Continued work should as a suggestion include several more interviews, collecting more material from around the divisions, more detailed calculations and a focus on the departments that are affected by the models.
Rapporten avhandlar ett förstudieprojekt för företaget EpirocRock Drills AB på avdelningen PLM Solutions. Företaget består av ett antal divisioner som alla arbetar med eller påverkas av CAD-modeller. PLM Solutions har länge sett ett behov av en gemensam metodik men på grund av prioriteringar av andra projekt har detta dröjt. Förstudiens syfte var att ta fram en kartläggning av den CAD-metodik som finns på företaget idag samt även se vilket behov av metodik som förekommer. Utifrån kartläggningen skulle en rekommendation ges i fråga om hur PLM Solutions skulle gå vidare vid ett större metodikprojekt. Rekommendationen var att skapa en övergripande gemensam CAD metodik och dra nytta av de redan existerande metoderna runt om i verksamheten. I och med att problemet behandlades som en förstudie utgörs också metoden av en förstudiemodell. Modellen är generell och anpassad för att passa just detta projekt. Tillvägagångssättet behandlar faserna uppstart, bakgrundsanalys och lösningar. I bakgrundsanalysen behandlas nulägesanalysen med hjälp av modeller för intervjuteknik. En större del av det underlag förstudien utgörs av, bygger på intervjuer med intressenter. Resultatet presenteras utifrån samma faser som metoden utgörs av. Resultatet består av en kartläggning av den metodik och behov som finns bland divisionerna, detta visualiseras också med hjälp av en SWOT-analys. Resultatet utgörs också av rekommendationen och kravspecifikationen som baseras på de intervjuer som utförts samt affärsfallet. Fortsatt arbetebör förslagsvis inkludera flerintervjuer, samla in mer material fråndivisionerna, mer utförliga beräkningar och ett större fokus på de avdelningar som påverkas av modellerna.

Unconfined multiple interacting confluent round jets are interesting from a purely scientific point of view, as interaction between neighboring jets brings additional complexity to the flow field. Unconfined confluent round jets also exist in various engineering applications, such as ventilation supply devices, sewage disposal systems, combustion burners, chemical mixing or chimney stacks. Even so, little scientific attention has been paid to unconfined confluent round jets. The present work uses both advanced measurement techniques and computational models to provide deeper understanding of the turbulent flow field development of unconfined confluent round jets. Both Laser Doppler Anemometry (LDA) and Particle Image Velocimetry (PIV) have been used to measure mean velocity and turbulence properties within two setups, consisting of a single row of 1×6 jets and a square array of 6×6 confluent jets. Simulations using computational fluid dynamics (CFD) of the 6×6 setup were conducted using three different Reynolds Averaged Navier-Stokes (RANS) turbulence models: the standard k-ε, the RNG k-ε and the Reynolds Stress model (RSM). The results from the CFD simulations were compared with experimental data. The employed RANS turbulence models were all capable of accurately predicting mean velocities and turbulent properties in the investigated confluent jet array. In general the RSM and k-ε std. models provided smaller deviations between numerical and experimental results than the RNG k-ε model. In terms of mean velocity the second-order closure model (RSM) was not found to be superior to the less complex standard k-ε model. The validated CFD model was employed in a parametrical investigation, including five independent variables: inlet velocity, nozzle diameter, nozzle edge-to-edge spacing, nozzle height and the number of jets in the array. The parametrical investigations made use of statistical methods in the form of response surface methodology. The derived response surface models provided information on the principal influence and relative importance of the investigated parameters within the investigated design space. The positions of the jets within the array strongly influence both mean velocity and turbulence. In all investigated setups the jets experience merging and combining. Square arrays also include considerable jet convergence, which was not present in the 1×6 jet array. Due to the jet convergence in square arrays the turbulent flow field, especially for jets far away from the array center, is affected by mean flow curvature. Jets located along the sides of square jet arrays experience strong jet-to-jet interactions that result in considerable jet deformation, shorter potential core, higher turbulent kinetic energy and faster velocity decay compared to other jets. Jets located at the corners of the array do not interact as strongly with neighboring jets as do the jets along the sides. The locations of merging and combined points differ considerably between different jets and different jet configurations. As the jets combine a zone with uniform stream-wise velocity and low turbulence intensity forms in the center of square jet arrays. This zone has been called Confluent Core Zone (CCZ) due to its similarities with the potential core zone of a single jet. Within the CCZ the appropriate scaling length changes from nozzle diameter to the effective source diameter. The parametrical investigation showed that nozzle diameter and edge-to-edge nozzle spacing were the most important of the investigated parameters, reflecting a strong dependence on dimensionless jet spacing, S/d0. Higher S/d0 delays both merging and combining of the jets and leads to a CCZ with lower velocity and longer downstream extension. Increasing the array size leads to a reduced combined point distance, a stronger inwards displacement of jets in the outer part of the array, and reduced entrainment near the nozzles. A higher inlet velocity was found to increase the jet convergence in the investigated square confluent jet arrays. Nozzle height generally has minor impact on the investigated response variables.

Диссертация на соискание ученой степени кандидата технических наук по специальности 05.05.16 – турбомашины и турбоустановки. – Национальный технический университет "Харьковский политехнический институт", Харьков, 2016. Диссертация посвящена разработке комбинированного метода аэродинамической оптимизации ступени осевой турбины, который основываясь на поочередном решении одномерной и трехмерной задач, позволяет значительно повысить эффективность всей ступени при этом учитывая как характер течения рабочего тела в решетках, так и влияние на него протечек. На основании современной тенденций к использованию методов вычислительной аэродинамики (CFD) при оптимизации проточных частей осевых турбин и при этом задействуя как можно большее количество управляющих параметров в оптимизационном процессе, предложен комбинированный метод оптимизации. Предложенный метод использует одномерную и трехмерную оптимизацию, что позволяет существенно повышать аэродинамическую эффективность ступеней, при этом значительно экономя время, необходимое для проведения расчетов. С помощью предложенного метода оптимизации и методики расчета протечек в осерадиальном уплотнении выполнена оптимизация 3-й ступени ЦВД турбины К-540-23,5. Результаты проведенных расчетов показали, что повышение эффективности ступени на этапе одномерной оптимизации происходит за счет выбора на среднем радиусе оптимальных α1, β2, значений степени реактивности ρ и относительного шага решетки t/b. Повышение эффективности ступени на этапе трехмерной оптимизации происходит за счет: выбора оптимального значения входного геометрического угла β1г рабочего профиля, обеспечившего улучшение обтекания профиля; устранения локальных диффузорных участков в межлопаточном канале; нахождения оптимальных законов закрутки, обеспечивающих равномерное натекание потока по всей высоте рабочих лопаток. Суммарно абсолютный КПД новой ступени увеличился более чем на 1 %.
Thesis for degree of Candidate of Sciences in Technique for speciality 05.05.16 – turbomachinery and turbine-installations. – National Technical University "Kharkiv Polytechnical Institute", Kharkiv, 2016. This thesis deals with the development of the combined method of aerodynamic optimization of the axial turbine stage, based on the iterative usage of one-dimensional and three-dimensional theories, thereby can significantly improve the efficiency of the entire stage taking into account the nature of the flow around turbine profiles and the impact of leakage on it. Based on current trends of using computational fluid dynamic methods (CFD) while optimizing of the flow path of the axial turbines, with engaging the largest pos-sible number of control parameters in the optimization process, the combined optimization method is provided. Developed method uses one-dimensional and three-dimensional optimization theories and can noticeably improve aerodynamic efficiency of whole turbine stage, thus significantly saving the time required for the simulations. A three-step comprehensive comparison of the results of simulations with the experimental data confirmed the accuracy of CFD usage while developing the optimization method. To calculate amount of leakage in the radial clearance during one-dimensional optimization phase more accurate, the methodology of flow rate determining in axial-radial seals depending on geometrical, operational characteristics and considering rotor against stator displacement was developed using a series of CFD simulations. Advanced CFD study was conducted to compare the axial-radial seal with the straight-flow one and to identify the new more effective designs of seal. It was shown that creation of artificial roughness on the shaft of the straight-flow seal could reduce the leakage by 45 % compared to the axial-radial seal. Utilizing the developed optimization method and the methodology of leakage calculation in the axial-radial seal, the optimization of the 3rd stage of the high pressure turbine K-540-23,5 was made. As a result of the optimization a new stage with an absolute efficiency increase more than 1 % compared to the original design was obtained.

Дисертація присвячена розробці комбінованого методу аеродінамічної оптимізації ступеня осьової турбіни, який ґрунтуючись на почерговому вирішенні одновимірної та тривимірної задач, дозволяє значно підвищити ефективність всього ступеня враховуючи як характер течії робочого тіла в решітках, так і вплив на неї витоки. На підставі сучасної тенденцій до використання методів чисельної аеродинаміки (CFD) при оптимізації проточних частин осьових турбін і при цьому задіяючи якомога більшу кількість управляючих параметрів в оптимізаційному процесі, запропонований комбінований метод оптимізації. Запропонований метод використовує одновимірну та тривимірну оптимізації, що дозволяє істотно підвищувати аеродинамічну ефективність ступенів, при цьому значно заощаджуючи час, необхідний для проведення розрахунків. При розробці методу оптимізації достовірність застосування методів CFD підтверджена шляхом триетапного порівняння результатів розрахунків з результатами експериментальних досліджень. Для отримання більш точних даних кількості витоки робочого тіла в радіальний зазор при проведенні етапу одновимірної оптимізації, розроблена методика для визначення коефіцієнта витрати вісерадіального ущільнення в залежності від його геометричних і режимних характеристик, а також з урахуванням зсуву ротора відносно статора від теплового розширення. Дана методика розроблялася шляхом проведення серії CFD розрахунків. Додатково проведено CFD дослідження для порівняння вісерадіальних ущільнень з прямоточними та виявлення нових ефективних конструкцій ущільнень, яке показало, що шляхом створення штучної шорсткості на валу прямоточного ущільнення можна зменшити витрату через нього на 45 % в порівнянні з вісерадіальними ущільненнями. За допомогою запропонованого методу оптимізації та методики розрахунку витоки в вісерадіальному ущільненні виконана оптимізація 3-го ступеня ЦВТ турбіни К-540-23,5. Результати проведених розрахунків показали, що абсолютний ККД нового ступеня збільшився більш ніж на 1 %.
Thesis for degree of Candidate of Sciences in Technique for speciality 05.05.16 – turbomachinery and turbine-installations. – National Technical University "Kharkiv Polytechnical Institute", Kharkiv, 2016. This thesis deals with the development of the combined method of aerodynamic optimization of the axial turbine stage, based on the iterative usage of one-dimensional and three-dimensional theories, thereby can significantly improve the efficiency of the entire stage taking into account the nature of the flow around turbine profiles and the impact of leakage on it. Based on current trends of using computational fluid dynamic methods (CFD) while optimizing of the flow path of the axial turbines, with engaging the largest pos-sible number of control parameters in the optimization process, the combined optimization method is provided. Developed method uses one-dimensional and three-dimensional optimization theories and can noticeably improve aerodynamic efficiency of whole turbine stage, thus significantly saving the time required for the simulations. A three-step comprehensive comparison of the results of simulations with the experimental data confirmed the accuracy of CFD usage while developing the optimization method. To calculate amount of leakage in the radial clearance during one-dimensional optimization phase more accurate, the methodology of flow rate determining in axial-radial seals depending on geometrical, operational characteristics and considering rotor against stator displacement was developed using a series of CFD simulations. Advanced CFD study was conducted to compare the axial-radial seal with the straight-flow one and to identify the new more effective designs of seal. It was shown that creation of artificial roughness on the shaft of the straight-flow seal could reduce the leakage by 45 % compared to the axial-radial seal. Utilizing the developed optimization method and the methodology of leakage calculation in the axial-radial seal, the optimization of the 3rd stage of the high pressure turbine K-540-23,5 was made. As a result of the optimization a new stage with an absolute efficiency increase more than 1 % compared to the original design was obtained.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2003.
Includes bibliographical references (p. 169-172).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Modern engineering practice for designing physical products requires the creation of a CAD model of the design for documentation and manufacturing. As the design evolves from concept through to production, it is analyzed a number of times, in some cases using general parameters and in others requiring fine details of the product's form. The setup of each analysis is typically disjoint from the previous steps, inhibiting design changes and optimization. This thesis addresses these bottlenecks by proposing a methodology to use the CAD model of the system as the central element. The model is created at the earliest possible stage of the process following a strict synthesis procedure; it then forms a common base for all of the follow-on analyses and development. Computational tools are developed to aid in using the geometric and parametric information in the CAD model to setup simulations, as well as to dynamically drive the CAD model itself for design studies and optimization. The methods and tools are then applied to the design of a wind turbine for power production. Using a common CAD model, various analysis codes and optimization algorithms are applied to the design of the system, to lower the cost of delivered energy. Multidisciplinary aspects of wind turbine design including aerodynamics, structures, and economics are presented together with the employed modeling techniques. The demonstrated improvements achieved over the baseline design lend credence to the methodology, and demonstrate its effectiveness in enhancing the systems performance. The insights gleaned from the present work intimate promising directions for continued development both at the level of software tools and also effective methods for approaching multi-disciplinary design.
by Curran A. Crawford.
S.M.

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Universidade de Pernambuco
Um dos maiores desafios para a indústria de embarcados é fornecer produtos com alto nível de qualidade e funcionalidade, a um baixo custo e curto tempo de desenvolvimento, disponibilizando-o rapidamente ao mercado, aumentando assim, o retorno dos investimentos. Os requisitos de custo e tempo de desenvolvimento têm sido abordados com bastante êxito pela engenharia de software baseada em componentes (CBSE) aliada à técnica de reuso de componentes. No entanto, a utilização da abordagem CBSE sem as devidas verificações da qualidade dos componentes utilizados, pode trazer conseqüências catastróficas (Jezequel et al., 1997). A utilização de mecanismos apropriados de pesquisa, seleção e avaliação da qualidade de componentes são considerados pontos chave na adoção da abordagem CBSE. Diante do exposto, esta tese propõe uma Metodologia para Avaliação da Qualidade de Componentes de Software Embarcados sob diferentes aspectos. A idéia é solucionar a falta de consistência entre as normas ISO/IEC 9126, 14598 e 2500, incluindo o contexto de componente de software e estendendo-o ao domínio de sistemas embarcados. Estas normas provêem definições de alto nível para características e métricas para produtos de software, mas não provêem formas de usá-las efetivamente, tornando muito difícil aplicá-las sem adquirir mais informações de outras fontes. A Metodologia é composta de quatro módulos que se complementam em busca da qualidade, através de um processo de avaliação, um modelo de qualidade, técnicas de avaliação agrupadas por níveis de qualidade e uma abordagem de métricas. Desta forma, ela auxilia o desenvolvedor de sistemas embarcado no processo de seleção de componentes, avaliando qual componente melhor se enquadra nos requisitos do sistema. É utilizada por avaliadores terceirizados quando contratados por fornecedores a fim de obter credibilidade em seus componentes. A metodologia possibilita avaliar a qualidade do componente embarcado antes do mesmo ser armazenado em um sistema de repositório, especialmente no contexto do framework robusto para reuso de software, proposto por Almeida (Almeida, 2004)

New product development forms part of PLM (Product Lifecycle Management) which starts with the idea generation phase. This first step exerts an enormous impact on the reduction of costs and could subsequently produce a high return on investment. That is the underlying motivation for this research, the goal of which is to formulate a methodology, which might be used during the idea generation phase for innovative concepts. To ensure market competitiveness companies are pushing for more efficient and innovative product development. PLM allows for a better understanding of intellectual capital and the integration of different tools and methods to lead to new opportunities. CAD (Computer Aided Design) plays a key role in PLM and NPD (New Product Development). CAD initiates with sketches developed by using geometry. The aim of this research is to create a new methodology for concept generation, which can be used in CAD environments. The methodology therefore focuses on the space field; taking inspiration from biological systems, to maximize efficiency, and from technical systems, to use innovative principles. One aim is to overcome psychological inertia, intended as an indisposition to change inscribed in the human brain. This might be achieved by abstracting the area of solutions, which enhances the capacity of forming new mental associations, overcoming habits, shortcuts and preconceived solutions. Classes of biological geometrical features have been selected, described and related to the eco-efficiency effects. In order to carry out a validity test on the chosen key-features which described as bio-inspired geometrical features, a One Tail Hypothesis Test has been formulated (see paragraph 3.5). The experiment involves using the filters of eco-efficient parameters as established by the World Business Council for Sustainable Development. The first 210 patents were selected to establish whether there exists a level of correspondence which might lead to acknowledging the key features as being related with efficiency. This step has been devised as fundamental to proceed with the subsequent selection of patents (see Chapter 4). 10 couples of analogies for every feature have been selected, taking samples from the biological and technical populations (international patents) as described in Chapter 4. A reading system for each resulting pair has then been constructed. The differences of language used when comparing the functions, the similarities given by the geometrical variables, the inventive spatial principles of TRIZ and the eco-parameters of the World Business Council for Sustainable Development have all been taken into account in the design of the reading system. The current number of 70 couples serves only as a starting point and the number could be extended with representative examples, with the consequent reduction in uncertainty. The information obtained through the couples of analogies has been used to build a semantic mapping. This allows for enhanced integration with CAD and therefore in the complex product lifecycle management systems. In this way the information becomes more accessible, it can be modified, shared and used by all those involved in the diverse stages of the design process. The process involves a series of choices to be executed at every stage and in every area to create specific ontology. It is dependent on a set of concepts and the relationship which operate between concepts and domains. The resultant system of relations has been reproduced in a semantic map using Protégé.

O computador vem ocupando atualmente um papel de crescente destaque na vida do homem moderno. Nesse contexto, também a área de projeto e, mais particularmente, a do projeto de edifícios, encontram nele uma ferramenta de inestimável valor. Seu atual nível de utilização nesse setor, no entanto, não tem se aproveitado de todo o potencial oferecido. Um dos motivos que justificam tal fato está no desconhecimento, por parte dos projetistas, das reais possibilidades de emprego dos computadores na área do projeto de edifícios. Nesse sentido, o objetivo dessa Dissertação é contribuir para a organização dos conceitos necessários a tais empregos, bem como montar um painel sobre as perspectivas de utilização dessa poderosa ferramenta na área.
The computer is playing an increasing role in the life of the modern man. With this point of view the design and more specifically the building design can make the computer a valuable tool. However, despite the potential of this equipment, it has not been yet properly used. This happens because the designers do not know the actual possibilities of the use of computers for the building designs. This Dissertation aims to organize the concepts related with this possibilities and also to bring out the prospective uses of this power full tool in this area.

This report is the documentation of a master’s thesis which was conducted at Scania CV AB in Södertälje. In this study, the benefits, challenges and conditions of using parametric CAD-models for aiding CFD-simulations and performance-optimization in the product development within internal combustion engines have been assessed. The goal of the thesis included developing and proposing a methodology for design engineers at Scania which will aid them in creating parametric CAD-models which are robust, flexible, comprehensible and intelligent. The study also included assessing the benefits and pre-requisites of such methodology with both practical and theoretical approaches. The ultimate goal of this entire study was to create value for the organization by reducing lead-time in the design process while promoting the production of high quality products. A case-based approach was applied in the study in which modeling strategies resulting from practical investigations and analyzing existing methodologies were implemented on a CAD-model representing the gas-volume of a turbine volute. The chosen strategies were evaluated and subsequently documented as a part of the methodology or discarded depending on its support for the parameterization. The final methodology itself was evaluated based on the quality of the parameterized CAD-model, the time required to create the model and its compatibility to the present design process at Scania CV AB. Finally the methodology was discussed with respect to the different evaluations, and the defined research questions were discussed and answered. The results of the thesis revealed that if parametric CAD-models are made in a structured, standardized and conscious manner, they are able to be highly robust and flexible which gives the models the ability to assume a big set of different forms. The methodology is recommended to be tested in a pilot project and be implemented through internal courses at the company. It was concluded that a methodology which aids the design engineers in creating parametric CAD-models will be the key towards implementing parametric CAD-models in the company and also enabling the many benefits of parameterization, which includes reduced lead-time, enhanced component performance, increased knowledge about the component, and promotion of collaboration among engineers. It was also concluded that parametric models are best suited when the existing design freedom is big and when the time permits performance analyses via optimizations, while challenges include ensuring that the model is parameterized correctly with respect to the CFD-engineers’ wishes while taking into account the requirements from other disciplines. Therefore it is very important to establish a communication between the different engineers. Ultimately, when parametric models are established in the organization, they are recommended to be implemented eventually in both short-term and long-term projects within Scania for its beneficial properties.

The research establishes a methodology for developing Web-based CAD/CAM software systems to industrial quality standards in a time and cost e ective manner. The methodology de nes the scope of applicability, outlines major considerations and key principles to follow when developing this kind of software, describes an approach to requirements elicitation, resource allocation and collaboration, establishes strategies for overcoming uncertainty and describes the design concerns for industrial Web-based CAD/CAM systems. The crucial parts of the methodology are a novel project development model facilitating architecture optimisation early in the project to minimise total development e orts, create future-proof solutions and ensure system maintainability; and a novel approach for planning based on time reserve management and task prioritisation, which provides the exibility required for exploratory development while maintaining the main focus on project objectives. The e ectiveness of the Web-based CAD/CAM software development methodology has been examined using two real software development case studies: a Web-based CAD/CAM system for involute spur gear shaper cutters and a Web-based CNC code editor for online modi cation of the pro le for manufacturing gear shaper cutters. The development of case studies using the established methodology resulted in on-time delivery of two industrial browser-based CAD/CAM systems, that produce valid results, embrace all business processes associated with the application area, ensure all functional and non-functional requirements and are used in production now. The developed software products demonstrate robustness, performance, reliability, security and usability comparable with the standards of modern commercial software, utilise advantages of Web-based applications to the highest extent and con rm advantages of Web-based CAD/CAM software compared to similar desktop applications. E ectiveness of the proposed methodology for Web-based CAD/CAM software development was checked through validation, evaluation and analysis of case study results.

The purpose of this thesis was to develop methodologies and procedures for the construction and use of CAD part families. This project uses the software CADDS5 created by Computervision, Inc., and its "Family of Parts" module. This software allows the creation of an entire family of similar parts using a single parametric master model and a text file containing the necessary parameters for each member of the family. CADDS5 users at Raytheon were surveyed to determine how they use standard parts, what types of standard parts are used, and typical modeling strategies. A set of criteria were developed to determine which groups of parts would be good candidates to be used as test cases. Four test cases were used to develop the methodology or procedure for the creation of families of parts. In addition, efficient use of these part families required the development of a set of search engines to allow the users to find parts more easily, and a parts server to generate new family members. The Family of Parts software in CADDS5 serves as a starting point for the creation of a usable library of standard parts. However, it has a poor user interface and has no system for part management and database administration. This thesis has made up for several of these shortcomings, and has created the core of a working library that can be easily used by all of the designers without requiring detailed knowledge of the details behind the implementation. The methodology developed during this project provides the necessary information for designers to create the majority of standard parts in use at Raytheon. For those who want to expand the library, it has provided useful information that will help them create high-quality parts that will work well with this system.

Engineering aircraft systems is a complex task. Therefore models and computer simulations are needed to test functions and behaviors of non existing systems, reduce testing time and cost, reduce the risk involved and to detect problems early which reduce the amount of implementation errors. At the section Vehicle Simulation and Thermal Analysis at Saab Aeronautics in Linköping every basic aircraft system is designed and simulated, for example the fuel system. Currently 2-dimensional rectangular blocks are used in the simulation model to represent the fuel tanks. However, this is too simplistic to allow a more detailed analysis. The model needs to be extended with a more complex description of the tank geometry in order to get a more accurate model. This report explains the different steps in the developed methodology for combining 3-dimensional geometry models of any fuel tank created in CATIA with dynamic simulation of the fuel system in Dymola. The new 3-dimensional representation of the tank in Dymola should be able to calculate fuel surface location during simulation of a maneuvering aircraft.  The first step of the methodology is to create a solid model of the fuel contents in the tank. Then the area of validity for the model has to be specified, in this step all possible orientations of the fuel acceleration vector within the area of validity is generated. All these orientations are used in the automated volume analysis in CATIA. For each orientation CATIA splits the fuel body in a specified number of volumes and records the volume, the location of the fuel surface and the location of the center of gravity. This recorded data is then approximated with the use of radial basis functions implemented in MATLAB. In MATLAB a surrogate model is created which are then implemented in Dymola. In this way any fuel surface location and center of gravity can be calculated in an efficient way based on the orientation of the fuel acceleration vector and the amount of fuel. The new 3-dimensional tank model is simulated in Dymola and the results are compared with measures from the model in CATIA and with the results from the simulation of the old 2-dimensional tank model. The results shows that the 3-dimensional tank gives a better approximation of reality and that there is a big improvement compared with the 2-dimensional tank model. The downside is that it takes approximately 24 hours to develop this model.
Att utveckla ett nytt flygplanssystem är en väldigt komplicerad arbetsuppgift. Därför används modeller och simuleringar för att testa icke befintliga system, minska utvecklingstiden och kostnaderna, begränsa riskerna samt upptäcka problem tidigt och på så sätt minska andelen implementerade fel. Vid sektionen Vehicle Simulation and Thermal Analysis på Saab Aeronautics i Linköping designas och simuleras varje grundflygplanssystem, ett av dessa system är bränslesystemet. För närvarande används 2-dimensionella rätblock i simuleringsmodellen för att representera bränsletankarna, vilket är en väldigt grov approximation. För att kunna utföra mer detaljerade analyser behöver modellerna utökas med en bättre geometrisk beskrivning av bränsletankarna. Denna rapport går igenom de olika stegen i den framtagna metodiken för att kombinera 3- dimensionella tankmodeller skapade i CATIA med dynamisk simulering av bränslesystemet i Dymola. Den nya 3-dimensionella representationen av en tank i Dymola bör kunna beräkna bränsleytans läge under en simulering av ett manövrerande flygplan. Första steget i metodiken är att skapa en solid modell av bränslet som finns i tanken. Därefter specificeras modellens giltighetsområde och alla tänkbara riktningar hos accelerationsvektorn som påverkar bränslet genereras, dessa används sedan i den automatiserade volymanalysen i CATIA.  För varje riktning delar CATIA upp bränslemodellen i ett bestämt antal delar och registrerar volymen, bränsleytans läge samt tyngdpunktens position för varje del. Med hjälp av radiala basfunktioner som har implementerats i MATLAB approximeras dessa data och en surrogatmodell tas fram, denna implementeras sedan i Dymola. På så sätt kan bränsleytans och tyngdpunktens läge beräknas på ett effektivt sätt, baserat på riktningen hos bränslets accelerationsvektor samt mängden bränsle i tanken. Den nya 3-dimensionella tankmodellen simuleras i Dymola och resultaten jämförs med mätningar utförda i CATIA samt med resultaten från den gamla simuleringsmodellen. Resultaten visar att den 3-dimensionella tankmodellen ger en mycket bättre representation av verkligheten och att det är en stor förbättring jämfört med den 2-dimensionella representationen. Nackdelen är att det tar ungefär 24 timmar att få fram denna 3-dimensionella representation.

Teil 1 Karsten Berndt Die Festlegung von Toleranzen ist eine alltägliche Aufgabenstellung des Konstrukteurs. Dabei bedingt die Berechnung nichtlinearer Toleranzketten einen erheblichen Zeitaufwand, wodurch meist auf deren genaue Berechnung vezichtet wird und Toleranzen stattdessen auf Basis von Erfahrungswerten festgelegt werden. Die vorgestellte Methodik zeigt Wege, wie schnell und frühzeitig im Konstruktionsprozess belastbare Aussagen zu Toleranzen komplexer Mechanismen getroffen werden können. Dazu werden sogenannte Sensitivitätsanalysen in der CAD-Software "Creo Elements" durchgeführt und ausgewertet. Das Ergebnis sind erste konkrete Toleranzfelder für alle den Mechanismus beschreibenden, geometrischen Abmessungen, welche sich als Startwerte für den anschließenden Toleranzsynthese/-analyseprozess eignen. Teil 2 Marko Ebermann Dieser zweite Vortragsteil behandelt eine mögliche Vorgehensweise zur Tolerierung von Geometrieabweichungen in der frühen Entwurfsphase am Beispiel des Koppelgliedes einer Verpackungsmaschine. Ausgangspunkt für die frühe Tolerierung bildet die im ersten Vortragsteil behandelte Sensitivitätsanalyse des Koppelgetriebes, welche Informationen zur Empfindlichkeit der Funktionsmaße bezüglich der Einhaltung der Schließmaßtoleranz lieferte. Die daraus abgeleitete Form- und Lagetolerierung des Koppelgliedes soll durch anschließende Toleranzamalysen die Tolerierung im Baugruppenkontext bestätigen und auf möglich Fertigungsverfahren abzielen, ohne die genaue Gestalt der Komponenten zu kennen. So können teure und zeitintensive Iterationsschleifen im Konstruktionsprozess minimiert und die Funktionalität frühzeitig gesichert werden.

This dissertation presents a method for the design of customizable products that interface with the human body. The method presented involves first, a consistent method of capturing and representing the human model so that the model can be used with CAx tools and solid modeling techniques. Second, it provides a design methodology based on feature structure planning and assembly modeling that provides a consistent structure to the design process so that it can be reused and parameterized. Third, a strategy for identifying parametric variables that are referenced to the human body is introduced. The core of this method is the definition of biomechanical products as an assembly model, where human data is defined as the base part. This research expands on traditional mating conditions in assembly model methods by identifying different ways products can interface with the human body. With the identification of these mating conditions, products can be designed to interact with the body in definable ways through the definition of parametric strategies. This dissertation also presents the necessary theoretical and numerical methods for implementation of these mating conditions in a CAD system.

A determinação do Alinhamento das Lagoas Urbanas é hoje no contexto das grandes cidades, uma questão complexa e polêmica, iniciada pela necessidade de Manutenção Ambiental daqueles espelhos d água, suas margens e características paisagísticas, considerando todo o manancial hidráulico e biológico envolvido (ecossistema), mas ao mesmo tempo atendendo a premente necessidade e determinação do Uso do Solo Urbano, com as diversas necessidades de ocupação e expansão, que encontram nas margens e adjacências dessas lagoas, uma válvula de escape oportuna e atraente, principalmente por suas características naturais, que acabam por oferecer paisagens belas e prazerosas, remetendo inclusive e principalmente a Valorização Imobiliária. Observa-se em diversas cidades, o quanto é atraente e interessante sobre o Aspecto Urbanístico e Paisagístico, os bairros, regiões e ocupações adjacentes a esses espelhos d água. Considerando a complexidade e motivação do assunto, inserido no Contexto Social, Ambiental, Urbano e Tecnológico atual, o Estudo das Condicionantes que venham a definir e implantar o Alinhamento das Lagoas Urbanas, de modo a preservar as melhores condições ambientais da região, utilizando tecnologias digitais de Sistemas de Desenho em CAD e Sistemas de Informação Geográfica – SIG, para a montagem, estruturação, comparação e análises dos dados envolvidos e pesquisados na Web, motivou a escolha e objetivos desta dissertação.
In various cities is observed how much is attractive and interesting about the urban and landscape aspect, neighborhoods, regions and occupations adjacent the Urban Lagoons. Considering the complexity of the subject, the objective of this work is to propose methodology for the study of conditioning factors that can influence the determination of the limits of the alignment of urban lagoons in order to preserve the best conditions and environmental characteristics of the region, using CAD technology and GIS for the analysis and selection of such conditions.

Актуальность темы магистерской диссертации обусловлена возможностью практического применения методики внедрения CAD / CAM систем в стоматологические клиники. Научная новизна исследования состоит в том, проанализировано развитие ИТ в различных отраслях, определены преимущественные направления и инновационные эффекты от применения ИТ в отраслях промышленности. Результаты работы: разработан готовый проект внедрения CAD/CAM системы в стоматологическую клинику «Жемчуг» с учетом особенностей предприятия. Практическая значимость: разработанный план может быть внедрен в любую стоматологическую клинику при учете особенностей предприятия. Экономическая эффективность предлагаемых в диссертации мер обусловлена тем, что внедряемая CAD/CAM система окупится на двадцать четвертом месяце после начала ее опытной эксплуатации и в последующем будет приносить стабильный доход.
The relevance of the topic of the master's thesis is due to the possibility of practical application of the methodology for the implementation of CAD / CAM systems in dental clinics. The scientific novelty of the research consists in analyzing the development of IT in various industries, identifying the preferential directions and innovative effects from the use of IT in industries. Results of work: a ready-made project for the implementation of a CAD / CAM system in the dental clinic "Pearl" was developed, taking into account the characteristics of the enterprise. Practical significance: the developed plan can be implemented in any dental clinic, taking into account the characteristics of the enterprise. The economic efficiency of the measures proposed in the dissertation is due to the fact that the implemented CAD / CAM system will pay off in the twenty-fourth month after the start of its trial operation and subsequently will bring a stable income.

Education in Saudi Arabia has received considerable attention from the government in the hope of finding strategies to improve the performance of schools, which is essential for economic development. However, education in Saudi Arabia has been criticised due to the quality of teachers, their salary, and the curricula and resources used (Khashoggi, 2014; Lindsey, 2010). Although the international literature reviews important issues of efficiency in education, there are few research projects which studies the efficiency challenges and constraints pertinent to Saudi schools in depth. The purpose of this research is to use Operational Research (OR) models focused on assessing and improving the performance of private schools in the Kingdom of Saudi Arabia, especially the Riyadh districts. A set of models are developed based on 57 schools for descriptive efficiency measurement and 12 schools for prescriptively improving the performance. Data collection was implemented through the Quality and Planning Department of the Saudi Ministry of Education who liaised with the school managers. In terms of model formulation, the techniques of: Data Envelopment Analysis (DEA) for measuring efficiency, the Analytical Hierarchy Process (AHP) for ranking priority of the criteria of improving school performance, and Goal Programming (GP) for improving the efficiency of schools are used in a combined framework. A subsidiary Goal Programming model for resolving the inconsistencies in the AHP preferences is also used. The results that can be obtained from building these models can be beneficial for parents, schools, and governments. Efficient schools yield better outcomes and support a higher quality of education, which increases the knowledge and skills of students. Those students will then contribute more effectively to the future development of their countries. In addition, high-performing schools delivering high levels of education to students can encourage the economic growth of a nation.

Droop-Nose Leading Edge (DNLE) morphing wings are one of the most promising devices in order to achieve aerodynamic drag and noise reduction during take-off and landing phases. An accurate design of these structures could lead to the decrease of aircraft fuel consumption in the perspective of reaching a greener aviation, following the objectives indicated by Flightpath 2050 issued by the E.U. However, due to the challenges related to the realization of this technology and TRL reached, DNLE are more likely implemented in Unmanned Aerial Systems (UAS) for testing and evaluation purposes. In the present study, an optimization methodology for the DNLE composite laminate skin and morphing mechanism structure is proposed and applied to a study case represented by the UAS-S45 aircraft. The work starts from the morphing leading edge structure developed by the LARCASE laboratory at ETS Montreal. The results showed that by means of the optimization strategy adopted, the force required on the actuator mechanism is 88% lower than the original design. A significant improvement on the profile smoothness along its section and in the spanwise direction in morphing conditions has been obtained too. However, further investigations are still needed in order to achieve a more appropriate morphing shape. Despite this, it appears from the results obtained that the proposed methodology can be useful to tackle the DNLE design problem in an effective and efficient way. What developed in this work has been conceived to support the investigation of DNLE in the small leading edge profiles typical of the UAS. In this way, an easier procedure for the set up of the design flow, and a decrease in the computational effort for the optimization process can be obtained. An experimental validation of the results obtained is currently being performed at ETS, and future development regards the assessment of the errors of the numeric procedure herein presented respect to real data.

This report documents a thesis conducted at Scania CV AB in Södertälje, Sweden. The main purpose of the thesis has been to examine and improve upon current practices of parametric CAD-modeling at Scania, with the ultimate goal of increased design automation and simulation-driven design. The thesis was initiated with a literature study, mainly covering the fields of parametric CAD-modeling, design automation and knowledge-based engineering. Furthermore, a questionnaire and multiple interviews were conducted to assess the awareness and mind-set of the employees. Finally, a case-study was carried out to follow current methodologies, and address any deficiencies found. Some of the most important findings were that while parametric modeling has considerable potential in enabling design automation, it is crucial, and most beneficial in terms of automation efficiency, to start with the fundamentals, namely achieving a uniform modeling practice. With these findings, a new proposed methodology has been introduced, as well as a recommended plan for a widespread implementation of parametric modeling at Scania. Such implementation would allow for shorter lead-times, faster adaptation to changing conditions, and reduced development expenditures.

Les réacteurs de IVème génération à neutrons rapides offrent la possibilité de valoriser le plutonium produit par le parc actuel des réacteurs à eau légère et de transmuter une part déterminante des déchets ultimes. Actuellement, de nouveaux projets de réacteurs à neutrons rapides sont étudiés dans le monde et doivent satisfaire de nouvelles exigences en termes d’économie des ressources, de réduction des déchets, de compétitivité, de sûreté et de fiabilité. Ainsi, ces nouveaux projets intègrent des innovations qui permettent d’améliorer la sûreté du réacteur (comportement naturel du coeur) en cas d’accident. Dans le cas du prototype ASTRID étudié en France au CEA, ces innovations portent sur le design géométrique du coeur et notamment l’intégration d’une plaque fertile au centre et d’un plenum de sodium en partie supérieure afin d’augmenter les fuites de neutrons en cas de vidange en sodium. Ces designs hétérogènes sont caractérisés par des vidanges en sodium proches de zéro résultant de fortes compensations entre les différentes zones du coeur. L’évaluation des grandeurs neutroniques d’intérêt nécessitent alors des outils de calculs robustes dans le but de traiter rigoureusement le transport des neutrons, et notamment au niveau des interfaces entre milieux. Le premier travail de thèse a donc consisté à améliorer la méthodologie existante permettant d’évaluer au mieux les grandeurs neutroniques d’intérêt. Ces améliorations ont consisté à développer une méthode d’analyse spécifique basée sur la théorie des perturbations et l’utilisation d’un solveur de flux moderne en transport Sn. Ce travail a permis d’une part, de réduire les biais de calcul sur les grandeurs neutroniques d’intérêt par rapport à des méthodes de référence (Monte Carlo) et, d’autre part, d’obtenir des distributions spatiales des effets neutroniques plus précises, et notamment des coefficients locaux de contre-réactions utilisés pour les analyses de transitoires non-protégés caractérisant le niveau « naturel » de « sûreté » du coeur. Par ailleurs, les incertitudes sur ces paramètres neutroniques ont un impact important sur les performances et la sûreté du coeur en termes de marges à prendre lors de la phase de conception. Il est donc important de les maîtriser et de les réduire afin de conserver les gains envisagés par le concept CFV. Ces incertitudes ont pour origines : les données nucléaires (sections efficaces macroscopiques pour une composition du coeur donnée), les données technologiques (données de fabrication et notamment la géométrie, les concentrations atomiques des constituants du coeur et les lois de dilatations thermiques),l’évolution du bilan matière dans le coeur sous irradiation, la thermique du combustible, les biais provenant des solveurs, des schémas de calculs (et de la modélisation) et des méthodes utilisées. Par ailleurs, les incertitudes sur la composition du coeur irradié et la thermique du combustible sont elles-mêmes fortement affectées par celles sur les données nucléaires. La propagation des incertitudes issues des données nucléaires sur les grandeurs neutroniques est donc complexe car faisant intervenir plusieurs sources de corrélation. Cette complexité est en outre accrue si l’on souhaite évaluer la corrélation spatiale des grandeurs neutroniques et des incertitudes associées. Le deuxième objectif de la thèse a donc consisté à mettre en place une méthodologie permettant de propager les incertitudes issues des données nucléaires sur les grandeurs neutroniques. Cette méthodologie se base sur l’évaluation de coefficients locaux de sensibilités permettant de déterminer les corrélations entre les différents paramètres neutroniques. (...)
Fast reactors (FR) can give value to the plutonium produced by the existing light water reactors and allow the transmutation of a significant part of the final nuclear waste. These features offer industrial prospects for this technology and new projects are currently studied in the world such as ASTRID prototype in France. Future FRs will have also to satisfy new requirements in terms of competitiveness, safety and reliability. In this context, the new core concept envisaged for ASTRID incorporate innovative features that improve the safety of the reactor in case of accident. The proposed design achieves a sodium voiding effect close to zero: it includes a fertile plate in the middle of the core and a sodium plenum in the upper part in order to increase the neutron leakage in case of sodium voiding. This heterogeneous design represents a challenge for the calculation tools and methods used so far to evaluate the neutronic parameters in traditional homogeneous cores. These methods have been improved over the thesis to rigorously treat the neutron streaming, especially at the mediums interfaces. These enhancements have consisted in the development of a specific analysis methodology based on perturbation theory and using a modern three dimensional Sn transport solver. This work has allowed on the one hand, to reduce the bias on static neutronic parameters in comparison with Monte Carlo methods, and, on the other hand, to obtain more accurate spatial distributions of neutronic effects including the reactivity feedback coefficients used for transient analysis. The analysis of the core behavior during transients has also allowed estimating the impact of reactivity feedback coefficients assessment improvements. In conjunction with this work, innovative methods based on the evaluation of local sensitivities coefficients have been proposed to assess the uncertainties associated to local reactivity effects. These uncertainties include the correlations between the different local parameters. The propagation during transients with these methods has allowed an estimation of temperature distributions achieved in the core and also to determine the available safety margins before sodium boiling

Os sistemas dinamicamente reconfiguráveis (SDRs) são uma alternativa para o desenvolvimento de sistemas sobre silício baseados em circuitos programáveis (SoPC), cujo principal beneficio é o bom aproveitamento da área do dispositivo. Sendo neles implementados circuitos que representam as tarefas que devem operar numa etapa específica do tempo de operação do sistema, permitem um menor consumo de área e de energia, parâmetros importantes nos sistemas portáveis. Isto tem gerado muito interesse no que se refere às metodologias de projeto utilizando FPGAs (Field Programmable Gate Arrays) dinamicamente reconfiguráveis (DRFPGAs) e à definição de um meio de comunicação estruturado para tratar da transferência de dados entre as partes reconfiguráveis e as fixas, mas estas tarefas, assim como a concretização de sua comunicação, seguem sendo ainda essencialmente manuais, devido à falta de metodologias de projeto e ferramentas de CAD que simplifiquem o projeto de SDRs. Este trabalho foca uma das limitações mais efetivas para a adoção da reconfiguração dinâmica: a falta de ferramentas de CAD que suportem o projeto de SDRs, inclusive os baseados em redes intra-chip (NoCs), em particular, no posicionamento dos módulos. Neste trabalho, uma arquitetura para SDRs baseado em NoCs é proposta e um algoritmo de posicionamento dos módulos de um SDR baseado em aspectos reais da família do DRFPGAs é desenvolvido, dentro de uma ferramenta denominada DynoPlace. Desenvolveu-se também um modelo de validação e simulação de SDRs, em tempo de operação, utilizando-se a técnica de chaveamento dinâmico de circuitos. Para o estudo do caso, de validação da arquitetura e metodologia, propõe-se uma aplicação teste baseada em computação de operações aritméticas. A metodologia de simulação permite determinar o tempo da reconfiguração e verificar o comportamento do SDR no momento da reconfiguração. A ferramenta DynoPlace permite gerar os arquivos de restrição de usuário (UCF) de posicionamento dos módulos do SDR no DRFPGA Virtex-4LX25. Este contém informações do posicionamento dos módulos do sistema, dos dispositivos usados para as entradas e saídas do sistema além do posicionamento dos bus-macros. Com os arquivos gerados pela metodologia e ferramenta DynoPlace, pode-se executar com sucesso os scripts da metodologia Early Access da Xilinx para gerar o SDR de forma automática.
Dynamically Reconfigurable Systems (DRSs) are an alternative for developing Systems on a Programmable Chip (SoPC), being the efficient use of device\'s area one of its main advantages. Circuits implemented as DRSs represent tasks which must be active in specific times into the system operation, allowing area and energy saving, which is an important goal for portable systems. This has generated interests on the design methodology using Dynamically Reconfigurable Field Programmable Gate Arrays (DRFPGAs) and on the definition of communication systems for handling data transfer between static and reconfigurable partitions. However, these tasks, as well as the communication structure, are still carried out manually due to lack of design methodologies and CAD tools applied to DRSs design. This work focuses on the one of main drawbacks to the adoption of dynamic reconfiguration methods: the absence of CAD tools which support DRS designs, specifically, in the module positioning task, included, for those based on Network-on-Chip (NoCs). In this work, an architecture for DRSs based on NoCs is presented and an algorithm for module positioning is developed in a tool called DynoPlace as well, based on real specifications of DRFPGAs families. It is also developed a run-time simulation and validation model for DRSs, through a dynamic circuit switching technique. For the validation of architecture and methodology study case, an application test based on arithmetic operations has been proposed. The simulations methodology allows to determine the reconfiguration time and verify the DRS behavior at the moment of reconfiguration. The DynoPlace tool allows to generate User Constraint File (UCF) of DRS\'s modules positioning for the DRFPGA Virtex-4LX25. This file contains information of modules positioning in the system, of the devices used for inputs and outputs of the system, and the positioning of bus-macros. After the files generation by the methodology, and the DynoPlace tool, it is possible to successfully execute the Early Access scripts for generating the DRS automatically.

[ES] El principal desafío en los motores turbina de gas empleados en aviación reside en aumentar la eficiencia del ciclo termodinámico manteniendo las emisiones contaminantes por debajo de las rigurosas restricciones. Ésto ha conllevado la necesidad de diseñar nuevas estrategias de inyección/combustión que operan en puntos de operación peligrosos por su cercanía al límite inferior de apagado de llama. En este contexto, el concepto Lean Direct Injection (LDI) ha emergido como una tecnología prometedora a la hora de reducir los óxidos de nitrógeno (NOx) emitidos por las plantas propulsoras de los aviones de nueva generación. En este contexto, la presente tesis tiene como objetivos contribuir al conocimiento de los mecanismos físicos que rigen el comportamiento de un quemador LDI y proporcionar herramientas de análisis para una profunda caracterización de las complejas estructuras de flujo de turbulento generadas en el interior de la cámara de combustión. Para ello, se ha desarrollado una metodología numérica basada en CFD capaz de modelar el flujo bifásico no reactivo en el interior de un quemador LDI académico mediante enfoques de turbulencia U-RANS y LES en un marco Euleriano-Lagrangiano. La resolución numérica de este problema multi-escala se aborda mediante la descripción completa del flujo a lo largo de todos los elementos que constituyen la maqueta experimental, incluyendo su paso por el swirler y entrada a la cámara de combustión. Ésto se lleva a cabo través de dos códigos CFD que involucran dos estrategias de mallado diferentes: una basada en algoritmos de generación y refinamiento automático de la malla (AMR) a través de CONVERGE y otra técnica de mallado estático más tradicional mediante OpenFOAM. Por un lado, se ha definido una metodología para obtener una estrategia de mallado óptima mediante el uso del AMR y se han explotado sus beneficios frente a los enfoques tradicionales de malla estática. De esta forma, se ha demostrado que la aplicabilidad de las herramientas de control de malla disponibles en CONVERGE como el refinamiento fijo (fixed embedding) y el AMR son una opción muy interesante para afrontar este tipo de problemas multi-escala. Los resultados destacan una optimización del uso de los recursos computacionales y una mayor precisión en las simulaciones realizadas con la metodología presentada. Por otro lado, el uso de herramientas CFD se ha combinado con la aplicación de técnicas de descomposición modal avanzadas (Proper Orthogonal Decomposition and Dynamic Mode Decomposition). La identificación numérica de los principales modos acústicos en la cámara de combustión ha demostrado el potencial de estas herramientas al permitir caracterizar las estructuras de flujo coherentes generadas como consecuencia de la rotura de los vórtices (VBB) y de los chorros fuertemente torbellinados presentes en el quemador LDI. Además, la implementación de estos procedimientos matemáticos ha permitido tanto recuperar información sobre las características de la dinámica de flujo como proporcionar un enfoque sistemático para identificar los principales mecanismos que sustentan las inestabilidades en la cámara de combustión. Finalmente, la metodología validada ha sido explotada a través de un Diseño de Experimentos (DoE) para cuantificar la influencia de los factores críticos de diseño en el flujo no reactivo. De esta manera, se ha evaluado la contribución individual de algunos parámetros funcionales (el número de palas del swirler, el ángulo de dichas palas, el ancho de la cámara de combustión y la posición axial del orificio del inyector) en los patrones del campo fluido, la distribución del tamaño de gotas del combustible líquido y la aparición de inestabilidades en la cámara de combustión a través de una matriz ortogonal L9 de Taguchi. Este estudio estadístico supone un punto de partida para posteriores estudios de inyección, atomización y combus
[CA] El principal desafiament als motors turbina de gas utilitzats a la aviació resideix en augmentar l'eficiència del cicle termodinàmic mantenint les emissions contaminants per davall de les rigoroses restriccions. Aquest fet comporta la necessitat de dissenyar noves estratègies d'injecció/combustió que radiquen en punts d'operació perillosos per la seva aproximació al límit inferior d'apagat de flama. En aquest context, el concepte Lean Direct Injection (LDI) sorgeix com a eina innovadora a l'hora de reduir els òxids de nitrogen (NOx) emesos per les plantes propulsores dels avions de nova generació. Sota aquest context, aquesta tesis té com a objectius contribuir al coneixement dels mecanismes físics que regeixen el comportament d'un cremador LDI i proporcionar ferramentes d'anàlisi per a una profunda caracterització de les complexes estructures de flux turbulent generades a l'interior de la càmera de combustió. Per tal de dur-ho a terme s'ha desenvolupat una metodología numèrica basada en CFD capaç de modelar el flux bifàsic no reactiu a l'interior d'un cremador LDI acadèmic mitjançant els enfocaments de turbulència U-RANS i LES en un marc Eulerià-Lagrangià. La resolució numèrica d'aquest problema multiescala s'aborda mitjançant la resolució completa del flux al llarg de tots els elements que constitueixen la maqueta experimental, incloent el seu pas pel swirler i l'entrada a la càmera de combustió. Açò es duu a terme a través de dos codis CFD que involucren estratègies de mallat diferents: una basada en la generación automàtica de la malla i en l'algoritme de refinament adaptatiu (AMR) amb CONVERGE i l'altra que es basa en una tècnica de mallat estàtic més tradicional amb OpenFOAM. D'una banda, s'ha definit una metodologia per tal d'obtindre una estrategia de mallat òptima mitjançant l'ús de l'AMR i s'han explotat els seus beneficis front als enfocaments tradicionals de malla estàtica. D'aquesta forma, s'ha demostrat que l'aplicabilitat de les ferramente de control de malla disponibles en CONVERGE com el refinament fixe (fixed embedding) i l'AMR són una opció molt interessant per tal d'afrontar aquest tipus de problemes multiescala. Els resultats destaquen una optimització de l'ús dels recursos computacionals i una major precisió en les simulacions realitzades amb la metodologia presentada. D'altra banda, l'ús d'eines CFD s'ha combinat amb l'aplicació de tècniques de descomposició modal avançades (Proper Orthogonal Decomposition and Dynamic Mode Decomposition). La identificació numèrica dels principals modes acústics a la càmera de combustió ha demostrat el potencial d'aquestes ferramentes al permetre caracteritzar les estructures de flux coherents generades com a conseqüència del trencament dels vòrtex (VBB) i dels raigs fortament arremolinats presents al cremador LDI. A més, la implantació d'estos procediments matemàtics ha permès recuperar informació sobre les característiques de la dinàmica del flux i proporcionar un enfocament sistemàtic per tal d'identificar els principals mecanismes que sustenten les inestabilitats a la càmera de combustió. Finalment, la metodologia validada ha sigut explotada a traves d'un Diseny d'Experiments (DoE) per tal de quantificar la influència dels factors crítics de disseny en el flux no reactiu. D'aquesta manera, s'ha avaluat la contribución individual d'alguns paràmetres funcionals (el nombre de pales del swirler, l'angle de les pales, l'amplada de la càmera de combustió i la posició axial de l'orifici de l'injector) en els patrons del camp fluid, la distribució de la mida de gotes del combustible líquid i l'aparició d'inestabilitats en la càmera de combustió mitjançant una matriu ortogonal L9 de Taguchi. Aquest estudi estadístic és un bon punt de partida per a futurs estudis de injecció, atomització i combustió en cremadors LDI.
[EN] Aeronautical gas turbine engines present the main challenge of increasing the efficiency of the cycle while keeping the pollutant emissions below stringent restrictions. This has led to the design of new injection-combustion strategies working on more risky and problematic operating points such as those close to the lean extinction limit. In this context, the Lean Direct Injection (LDI) concept has emerged as a promising technology to reduce oxides of nitrogen (NOx) for next-generation aircraft power plants In this context, this thesis aims at contributing to the knowledge of the governing physical mechanisms within an LDI burner and to provide analysis tools for a deep characterisation of such complex flows. In order to do so, a numerical CFD methodology capable of reliably modelling the 2-phase nonreacting flow in an academic LDI burner has been developed in an Eulerian-Lagrangian framework, using the U-RANS and LES turbulence approaches. The LDI combustor taken as a reference to carry out the investigation is the laboratory-scale swirled-stabilised CORIA Spray Burner. The multi-scale problem is addressed by solving the complete inlet flow path through the swirl vanes and the combustor through two different CFD codes involving two different meshing strategies: an automatic mesh generation with adaptive mesh refinement (AMR) algorithm through CONVERGE and a more traditional static meshing technique in OpenFOAM. On the one hand, a methodology to obtain an optimal mesh strategy using AMR has been defined, and its benefits against traditional fixed mesh approaches have been exploited. In this way, the applicability of grid control tools available in CONVERGE such as fixed embedding and AMR has been demonstrated to be an interesting option to face this type of multi-scale problem. The results highlight an optimisation of the use of the computational resources and better accuracy in the simulations carried out with the presented methodology. On the other hand, the use of CFD tools has been combined with the application of systematic advanced modal decomposition techniques (i.e., Proper Orthogonal Decomposition and Dynamic Mode Decomposition). The numerical identification of the main acoustic modes in the chamber have proved their potential when studying the characteristics of the most powerful coherent flow structures of strongly swirled jets in a LDI burner undergoing vortex breakdown (VBB). Besides, the implementation of these mathematical procedures has allowed both retrieving information about the flow dynamics features and providing a systematic approach to identify the main mechanisms that sustain instabilities in the combustor. Last, this analysis has also allowed identifying some key features of swirl spray systems such as the complex pulsating, intermittent and cyclical spatial patterns related to the Precessing Vortex Core (PVC). Finally, the validated methodology is exploited through a Design of Experiments (DoE) to quantify the influence of critical design factors on the non-reacting flow. In this way, the individual contribution of some functional parameters (namely the number of swirler vanes, the swirler vane angle, the combustion chamber width and the axial position of the nozzle tip) into both the flow field pattern, the spray size distribution and the occurrence of instabilities in the combustion chamber are evaluated throughout a Taguchi's orthogonal array L9. Such a statistical study has supposed a good starting point for subsequent studies of injection, atomisation and combustion on LDI burners.
Belmar Gil, M. (2020). Computational study on the non-reacting flow in Lean Direct Injection gas turbine combustors through Eulerian-Lagrangian Large-Eddy Simulations [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/159882
TESIS

The thesis will discuss the Systems Engineering phase of an original Conceptual Design Engineering Methodology for Aerospace Engineering-Vehicle Synthesis. This iterative phase is shown to benefit from digitization of Integrated Product&Process Design (IPPD) activities, through the application of Product Lifecycle Management (PLM) technologies. Requirements analysis through the use of Quality Function Deployment (QFD) and 7 MaP tools is explored as an illustration. A "Requirements Data Manager" (RDM) is used to show the ability to reduce the time and cost to design for both new and legacy/derivative designs. Here the COTS tool Teamcenter Systems Engineering (TCSE) is used as the RDM. The utility of the new methodology is explored through consideration of a legacy RFP based vehicle design proposal and associated aerospace engineering. The 2001 American Helicopter Society (AHS) 18th Student Design Competition RFP is considered as a starting point for the Systems Engineering phase. A Conceptual Design Engineering activity was conducted in 2000/2001 by Graduate students (including the author) in Rotorcraft Engineering at the Daniel Guggenheim School of Aerospace Engineering at the Georgia Institute of Technology, Atlanta GA. This resulted in the "Kingfisher" vehicle design, an advanced search and rescue rotorcraft capable of performing the "Perfect Storm" mission, from the movie of the same name. The associated requirements, architectures, and work breakdown structure data sets for the Kingfisher are used to relate the capabilities of the proposed Integrated Digital Environment (IDE). The IDE is discussed as a repository for legacy knowledge capture, management, and design template creation. A primary thesis theme is to promote the automation of the up-front conceptual definition of complex systems, specifically aerospace vehicles, while anticipating downstream preliminary and full spectrum lifecycle design activities. The thesis forms a basis for additional discussions of PLM tool integration across the engineering, manufacturing, MRO and EOL lifecycle phases to support business management processes.

The Particulate Matter is the most crucial parameter which decides the pollution level in air. The negative impact of particulate matter is solely because of its submicron size which causes bad effects on human. There are many air quality control devices available which separates out the particulate matter using different sets of principles. Cyclone Separator is a type of air quality control device which uses physical phenomenon of centrifugal acceleration. The efficiency of cyclone separator to eliminate particulate matter is average as compared to other devices and techniques but its cost efficiency is quite high due to its basic working principle and no moving parts. The polluted air enters tangentially from the inlet and descends in swirling pattern in the hollow cylinder and cone parts of the cyclone body. This spiral motion of particle laden air produces a centrifugal force on the particles and pushes them towards wall of the cyclone. Therefore, the designing and analysis of cyclone separator is difficult due to complex flow pattern. Pressure drop and different velocities generated through cyclone body is the most important parameter to predict its performance. Many studies and research work have been done in the field of cyclone separator but there are no specific techniques and empirical formulas to analyse the flow pattern and pressure drop. Solving the flow and particle transport equations using CFD (Computational Fluid Dynamics) approach is one of the method that can be followed with specific sets of equations and model. The present study is carried out to analyse the performance of three models of cyclone separator with different vortex finder diameter using RSM (Reynolds stress model) methodology to predict turbulent flow behaviour and DPM (Discrete phase model) to trace the particles trajectories through each cyclone model. The equations are solved computationally using the CFD based software FLUENT (v18.2). The case in the study is computed using an assumption of one-way coupling in the cyclone separator. The graphs and contours of velocities and pressure drop are analysed and compared to study the effect of varying diameter of vortex finder. Collection efficiency is determined by injecting a fixed number of particles from inlet and counting the trapped particles.

碩士
國立清華大學
核子工程與科學研究所
100
Nuclear power plant safety is one of the most important part issues of international energy usage nowadays. Generation IV nuclear reactors have been investigated and developed for a period of time, and will be one of the the major electricity supplies for the future global energy requirements efficiently and safely. High Temperature Gas Cooled Reactor (HTGR) is one type of generation IV reactors, which is developed successfully and waited for being used to solve future the energy shortage problem worldwide. Although, there is already highly safe design for HTGR, but deeper understanding and manipulating the hypothetical severe accident is still necessary. Air-ingress accident analysis of GEN IV HTGR is the main purpose of this study. In this study, CFD (Computational Fluid Dynamics) is used for investigating the thermal-hydraulic phenomena in HTGR while air-ingress is happening there after. At the beginning, normal operating conditions is obtained by steady-state simulation. Transient simulation is used for understanding the thermal-hydraulic phenomena of the HTGR core since the severe accident incipience. The pipe between reactor vessel and steam generator, which is called hot gas duct, broke during the accident started. This pipe broken will cause the outside air diffused into the reactor vessel. Fuel assembly will be corroded by oxygen, due to a series of chemical interaction between oxygen and high temperature graphite. As a result, radioactive fission products may be released into outside environment space. Obviously, the corrosion problem on fuel assembly is the key issue of HTGR safety. After a long period of interaction between oxygen and fuel assembly, the fuels in the lower region of the core damaged the most. As a consequence, some safety devices are needed to be design and equipped for making air diffuses uniformly in vessel to avoid the non uniformed corrosion situation.