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Anderle, Milan. "Vývoj modelu kalcinace pro ANSYS Fluent." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-367526.
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The aim of the diploma thesis was creating a decarbonisation model of lime, implementation the model into CFD tool ANSYS Fluent and to test the decarbonisation model in a model of a real reactor. The required model was based on assumptions for a Shrinking Core Model (SCM). The main objective of this work was the non-catalytic conversion of substances and the search for the most used mathematical models for calcination. The CFD calculation, the sensitivity analysis and the Fluente parametric study were used. Data on the composition of gas flow, temperature, pressure and mass flow of limestone particles were selected for input variables. The particle model called Multiple Surface Reactions (MSR), which is a standard part of Fluent, was used at first. Subsequently, a UDF which was based on the SCM assumptions was written in the programming language C. The results of the CFD calculation were compared with the experimental values from the dissertation. It has been found that the MSR is sufficiently precise for calculation purposes but neglects the internal diffusion of CO2 through the CaO layer which forms behind the reaction front during calcination. It was found that it is possible to solve the flow with ongoing calcination without the need to know the parameters of the Arrhenian equation if the UDF is used. The created UDF incorporates the influence of intraparticular CO2 diffusion on the overall reaction rate.
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Drexler, Pavel. "CFD analýza proudění vzduchu pro různé typy průtokoměrů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220888.
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There are some basic information about pressure sensors and flow in the first part of my diploma thesis. For example turbulent and laminar flow, construction of pressure sensors and basic information abaut Ansys and –Fluent. Main part of this thesis is focused on CFD simulation of pressure and velocity in the vicinity of pressure sensors. I confront this simulated values with measured values in final part of this thesis.
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LOPEZ, REBOLLAR BORIS MIGUEL 547458, and REBOLLAR BORIS MIGUEL LOPEZ. "Aplicación de cfd-ansys-fluent en el estudio hidrodinámico de tanques de recirculación empleados en acuacultura." Tesis de maestría, CENTRO INTERAMERICANO DE RECURSOS DEL AGUA - Universidad Autónoma del Estado de México, 2015. http://hdl.handle.net/20.500.11799/40428.
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Tesis que se presenta para obtener el grado de maestría en Ciencias del AguaLa Dinámica de Fluidos Computacional (CFD) tiene distintas aplicaciones en diversas áreas de la ingeniería, principalmente en la modelación de flujos, donde es utilizada para conocer las características de un flujo en movimiento y determinar las variables que intervienen en su comportamiento, de manera teórica pero económica y con resultados muy cercanos a la realidad. En acuacultura, la CFD es utilizada para visualizar y evaluar el comportamiento hidrodinámico de tanques de cultivo de peces, tomando en cuenta las condiciones de flujo para el sano desarrollo de los peces. Sin embargo, pocos trabajos analizan la eficiencia de remoción de sedimentos de forma natural, considerando el comportamiento del flujo dentro del tanque. En el presente trabajo, se analiza la hidrodinámica de un tanque de recirculación de agua empleado en acuacultura, aplicando simulación por computadora a través de técnicas CFD, demostrando la importancia de realizar simulaciones aplicando métodos numéricos, para la obtención de parámetros hidrodinámicos, principalmente, los campos de velocidad y turbulencia ante diversos escenarios de operación de un sedimentador tipo hidrociclón. Los resultados obtenidos demuestran que los principales factores que influyen en la hidrodinámica del tanque y del sedimentador son: la forma y distribución de rejillas del sedimentador, así como el diámetro del mismo. El efecto que producen dichas rejillas, son diversas variaciones en la distribución de velocidades del tanque y principalmente dentro del sedimentador, afectando las condiciones óptimas del flujo para la sedimentación de partículas y por ende la eficiencia en la remoción de sedimentos dentro del tanque. Con los resultados obtenidos mediante la aplicación de CFD fue posible relacionar la hidrodinámica del sedimentador con su diámetro y estructura de rejillas, logrando tener un flujo idóneo en el tanque para al sano desarrollo de los peces y un flujo con velocidad total máxima de 2 cm/s dentro del sedimentador, suficiente para lograr la sedimentación de partículas, y con ello generar un sistema con características de auto-limpieza.
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Jybrink, Anton. "Dynamic CFD Modelling of Deploying Fins During Transitional Ballistic." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70758.
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The transition from inner to outer ballistics is a crucial part for the stability of the projectile. A projectile is mainly stabilized in two ways, with fins or by rotation. This work is limited to analyze a fin stabilized projectile. The launch of the projectile and the deployment of the fins are a quick process, therefore high forces and high temperatures will act the stability of the projectile. Due to these factors, it is hard to quantify experiments to analyze the stability of the projectile. To gain knowledge about how the forces will affect the path of the projectile during the launch and the deployment of its fins Computational Fluid Dynamics (CFD) can be a useful technique. In this work, a 2D methodology have been developed in Ansys Fluent to analyze the launch of a projectile and the deployment of the fins. A RANS model have been used in combination of dynamic mesh in order to handle the movement of the projectile. The projectile accelerates due to a pressure rise which have been initialized by a mass flow and energy curve as a source term. This work indicates that it is possible to predict the flow behavior and the forces influencing the projectile and the deploying fins. This work used a 2D model throughout the simulations and a 3D model is therefore needed to further compare and validate the simulation methodology.
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Koren, Dejan. "Computational Fluid Dynamics Unstructured Mesh Optimization for the Siemens 4th Generation DLE Burner." Thesis, KTH, Mekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-178034.
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Every computational fluid dynamics engineer deals with a never ending story – limitedcomputer resources. In computational fluid dynamics there is practically never enoughcomputer power. Limited computer resources lead to long calculation times which result inhigh costs and one of the main reasons is that large quantity of elements are needed in acomputational mesh in order to obtain accurate and reliable results.Although there exist established meshing approaches for the Siemens 4th generation DLEburner, mesh dependency has not been fully evaluated yet. The main goal of this work istherefore to better optimize accuracy versus cell count for this particular burner intended forsimulation of air/gas mixing where eddy-viscosity based turbulence models are employed.Ansys Fluent solver was used for all simulations in this work. For time effectivisationpurposes a 30° sector model of the burner was created and validated for the meshconvergence study. No steady state solutions were found for this case therefore timedependent simulations with time statistics sampling were employed. The mesh convergencestudy has shown that a coarse computational mesh in air casing of the burner does not affectflow conditions downstream where air/gas mixing process is taking place and that a majorpart of the combustion chamber is highly mesh independent. A large reduction of cell count inthose two parts is therefore allowed. On the other hand the RPL (Rich Pilot Lean) and thepilot burner turned out to be highly mesh density dependent. The RPL and the Pilot burnerneed to have significantly more refined mesh as it has been used so far with the establishedmeshing approaches. The mesh optimization has finally shown that at least as accurate resultsof air/gas mixing results may be obtained with 3x smaller cell count. Furthermore it has beenshown that significantly more accurate results may be obtained with 60% smaller cell count aswith the established meshing approaches.A short mesh study of the Siemens 3rd generation DLE burner in ignition stage of operationwas also performed in this work. This brief study has shown that the established meshingapproach for air/gas mixing purposes is sufficient for use with Ansys Fluent solver whilecertain differences were discovered when comparing the results obtained with Ansys Fluentagainst those obtained with Ansys CFX solver. Differences between Fluent and CFX solverwere briefly discussed in this work as identical simulation set up in both solvers producedslightly different results. Furthermore the obtained results suggest that Fluent solver is lessmesh dependent as CFX solver for this particular case.
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Vince, Tomáš. "CFD analýza tepelného zatížení trubkovnice." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-443458.
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This diploma thesis focuses on the phenomena of multiphase flow in a steam generator as a one of probable causes of tubes and tubesheet weld cracking. In the first part of the work, a research was carried out focusing on the boiling and the phenomenon of two-phase flow in technical applications, its characteristics and properties. The thesis continuous with an overview of available numerical multiphase models in the ANSYS Fluent 2021 R1 and a research of previously published works focused on two-phase flow with the presence of boiling. The research is followed by a description of the particular boiler, which is part of the nitric acid production plant in the chemical company DUSLO, a.s., its operating conditions and a more detailed description of the issue that is being addressed in this thesis. The second part of the work continuous with a description of the computational model, including a description of the geometry of the model and used simplifications, the computational mesh and the description of boundary conditions. Important part is the description of calculation setting of steady-state and transient CFD simulations in ANSYS Fluent. Finally, the results of the two-phase flow calculation are presented and then discussed in the conclusions.
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Moghimi, Ardekani Mohammad. "Optical thermal and economic optimisation of a linear Fresnel collector." Thesis, University of Pretoria, 2017. http://hdl.handle.net/2263/61313.
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Solar energy is one of a very few low-carbon energy technologies with the enormous potential to grow to a large scale. Currently, solar power is generated via the photovoltaic (PV) and concentrating solar power (CSP) technologies. The ability of CSPs to scale up renewable energy at the utility level, as well as to store energy for electrical power generation even under circumstances when the sun is not available (after sunset or on a cloudy day), makes this technology an attractive option for sustainable clean energy. The levelised electricity cost (LEC) of CSP with thermal storage was about 0.16-0.196 Euro/kWh in 2013 (Kost et al., 2013). However, lowering LEC and harvesting more solar energy from CSPs in future motivate researchers to work harder towards the optimisation of such plants. The situation tempts people and governments to invest more in this ultimate clean source of energy while shifting the energy consumption statistics of their societies from fossil fuels to solar energy.
Usually, researchers just concentrate on the optimisation of technical aspects of CSP plants (thermal and/or optical optimisation). However, the technical optimisation of a plant while disregarding economic goals cannot produce a fruitful design and in some cases may lead to an increase in the expenses of the plant, which could result in an increase in the generated electrical power price.
The study focused on a comprehensive optimisation of one of the main CSP technology types, the linear Fresnel collector (LFC). In the study, the entire LFC solar domain was considered in an optimisation process to maximise the harvested solar heat flux throughout an imaginary summer day (optical goal), and to minimise cavity receiver heat losses (thermal goal) as well as minimising the manufacturing cost of the plant (economic goal). To illustrate the optimisation process, an LFC was considered with 12 design parameters influencing three objectives, and a unique combination of the parameters was found, which optimised the performance. In this regard, different engineering tools and approaches were introduced in the study, e.g., for the calculation of thermal goals, Computational Fluid Dynamics (CFD) and view area approaches were suggested, and for tackling optical goals, CFD and Monte-Carlo based ray-tracing approaches were introduced. The applicability of the introduced methods for the optimisation process was discussed through case study simulations. The study showed that for the intensive optimisation process of an LFC plant, using the Monte Carlo-based ray-tracing as high fidelity approach for the optical optimisation objective, and view area as a low fidelity approach for the thermal optimisation objective, made more sense due to the saving in computational cost without sacrificing accuracy, in comparison with other combinations of the suggested approaches.
The study approaches can be developed for the optimisation of other CSP technologies after some modification and manipulation. The techniques provide alternative options for future researchers to choose the best approach in tackling the optimisation of a CSP plant regarding the nature of optimisation, computational cost and accuracy of the process.Thesis (PhD)--University of Pretoria, 2017.
Mechanical and Aeronautical Engineering
PhD
Unrestricted
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Rogers, Charles. "Computational Fluid Dynamics Analysis of an Ideal Anguilliform Swimming Motion." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1940.
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There is an ongoing interest in analyzing the flow characteristics of swimming fish. Biology has resulted in some very efficient motions and formulating these motions is of interest to engineers. One such theory was written by Dr. William Vorus and Dr. Brandon Taravella involving ideal efficiency. It is therefore interesting to test the calculations to see if it is possible to design a motion that can create thrust without necessarily creating vorticity. The computational fluid dynamics software of ANSYS Fluent was used to calculate the resulting flow field of the eel motion to compare with the theoretical values.
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Kapell, Jennie. "Analysis of the Inner Flow in the Wave Energy Converter WaveTube." Thesis, KTH, Tillämpad termodynamik och kylteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-102293.
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Wave energy technology is currently growing and gaining popularity. With around 100 separate technologies researched globally in over 25 countries wave energy are believed to soon be able to compete with other renewable sources such as wind energy. One of the new technologies is WaveTube; a wave energy converter currently under development and in need of technical verification. The basic idea of WaveTube is a partially submerged container with an enclosed fresh water volume. The kinetic energy of the ocean waves are transferred onto the floating container, creating an inner flow in the structure and electricity is generated as the fresh water flows through turbines. Previous small-scale model tests have confirmed the basic idea of WaveTube and an inherent continuation is visualizing and evaluating the inner flow using Computational Fluid Dynamics. A simplified 2D simulation where the WaveTube structure is subject to a pure sinusoidal, rotational motion was believed to be able to give useful information about the inner flow field. However, this Master Thesis project shows that a simulation using ANSYS Fluent of this case is not a successful approach. With inner moving parts a so called dynamic mesh was required, which updates the mesh as the boundaries move. In order for this method to be successful the mesh needs to be of high quality. However, for the complex geometry that WaveTube is no mesh was found to meet the requirements and the calculations using the Volume of Fluid method were not able to proceed.
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Ekman, Petter. "A Sensitivity Study of Some Numerical and Geometrical Parameters Affecting Lift." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-124197.
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Volvo Car Corporation (VCC) uses Computational Fluid Dynamics (CFD) and wind tunnel during the aerodynamic development of new vehicles. In the past VCC main focus has been on the drag force correlation to the wind tunnel measurements but in recent years improved methods for lift force correlations has been highly wanted. Three objectives were considered in this study to improve the lift force correlation between the CFD simulations and wind tunnel measurements for geometrical configurations of the V60 and S60 models.Poor mesh resolution for the wall bounded flow existed for the VCC mesh method and therefore prisms layers were considered in this thesis to increase the mesh resolution inside the boundary layer.As slick tyres generally were used in the CFD simulations better geometrical correlation was wanted to be studied as it could improve the lift force correlation between CFD simulations and wind tunnel measurements. Therefore detailed tyres were considered in this study.As the coarsest surface mesh size was used for the underbody and the components inside the engine bay, where some of the highest flow velocities occurred, mesh refinements were investigated for engine bay and underbody in this study.The prisms layers improved the predicted behavior for the boundary layer as it captured the large velocity gradients more accurately. Due to this, the skin friction prediction was also improved. Different flow behavior around the front wheels and rear wake occurred due to earlier separation. The different flow field caused an improved correlation for the lift force but worsened correlation for the drag force due to increased pressure at the rear of the cars. However, the front lift force trend correlation for the considered configurations was improved with the prisms layer mesh method.The detailed tyres caused slight more disturbances for the underbody flow which caused more attached flow around the rear of the car hence lowered pressure. Earlier separation around the front wheels also occurred for the detailed tyre geometry as the disturbed flow around the wheels was increased. Slight improved correlation for the front and rear lift forces to the wind tunnel measurements could be seen with the detailed tyre compared to the slick tyre.The mesh refinements for the engine bay and underbody showed significant differences for the flow at the underbody which had significant impact on the flow at the rear wake for the V60 model. Minor differences could be seen for the aerodynamic forces for the baseline configuration for the V60 model while great differences occurred for the configurations affecting the underbody. Due to this significant improved correlation for the front and rear lift force trends were achieved for the underbody configurations with the refined engine bay and underbody mesh method.Conclusions could be drawn that the prisms layer caused earlier separation due to its increased mesh resolution for the wall bounded flow. However, finer mesh resolution was needed inside the boundary layer to ensure consistent separation behavior for both the considered models. Improved correlation for the front lift force could however be seen. The detailed tyre only had minor effects on the flow field and aerodynamic forces and therefore not so important to include for further studies. The refined engine bay and underbody caused significant improved lift force trend correlation to the wind tunnel measurements and should be considered for future studies. To improve the correlation between CFD simulations and wind tunnel measurements increased mesh resolution for the wall bounded flow should be considered to better capture the large velocity gradients close to the wall.
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Mačák, Martin. "Modelování magnetohydrodynamických jevů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-377336.
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Theoretical part of this thesis is dedicated to the theoretical basis of electric conduction phenomena in fluids and method of calculation of magnetohydrodynamic phenomena. In the experimental part, computational modules have been developed to complement and augment the use of commercial simulation programs for simulation in the field of magnetohydrodynamics. On practical examples of mass spectrometer simulation, Einzel lens, electron movement and electric circuit breaker, the functionality of the computational models and the correctness of the obtained results were documented. Created computational modules can be used to design and optimize products using magnetohydrodynamic phenomena.
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Matteucci, Simona. "Numerical Modelling of a Flameless Combustor." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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Flameless combustion can be adopted as a low-emission combustion regime in the aviation sector, which is one of the biggest contributors to NOx emissions and is expected to grow in the near future. Nevertheless, several issues must be solved before any practical applications. Effective design procedure must deal with either combustion or heat transfer phenomena occurring at extremely low—temperature conditions. To this aim, experimental and numerical analyses focused on the characterization of fuel/oxidant behaviour are strongly needed and represent an essential step for further development.
Besides, the complexity of the analysed technological system requires advanced tools for the definition of the chemical kinetics, for the burner designs and more in general for the definition of aviation equipment design. In this light, the thesis has been addressed to the study of flameless combustion mechanisms within a combustion chamber prototype developed in the Faculty of Aerospace Engineering at TU Delft. In particular, the temperature and species concentration fields have been analysed. The CFD tool which will be used is Ansys Fluent together with two detailed reaction mechanisms (KIBO and RDM19).
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Kent, Jason A. "Numerical and Experimental Analysis of a TurboPiston Pump." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1189.
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The TurboPiston Pump was invented to make use of merits such as, high flow rates often seen in centrifugal pumps and high pressures associated with positive displacement pumps. The objective of this study is to manufacture a plastic model 12†TurboPiston Pump to demonstrate the working principle and a metal prototype for performance testing. In addition, this research includes the study of the discharge valve to estimate the valve closing time and fluid mass being recycled back into the cylinder through hand calculations. Furthermore, a transient simulation was performed in CFD using Fluent to provide a better estimate of what will happen in the actual pump while running. Additionally, an experimental rig was designed to investigate the performance of the first generation valve on the TurboPiston Pump known as the flapper valve. Means to improve the hydrodynamic performance of both valves have been identified for future study.
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Vobejda, Radek. "Výpočtové modelování aerodynamického hluku způsobeného bočním zrcátkem automobilu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401556.
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The master’sthesis deals with numerical modelling of aerodynamic noisewhich arisesinside of the carcabin. In the first part ofthe thesis simplified model of geometry of the car and of the inside acoustic pressure arecreated. After that numerical analysis of created models of geometry are doneandvarious models of turbulenceare discussed. The results of these CFD simulationswhere then used for changing the model of geometry of the wing mirror. Outputs of these simulations were used for solving the numerical analysis of noise in the car cabin.
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Kácal, Jan. "Optimalizace klapek pro letouny SKYLEADER." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-319260.
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This diploma thesis focuses on optimization of the flap for the ultralight aircraft Skyleader JA 600, which is produced by the Jihlavan s.r.o. company. Individual types of flaps used in ultralight aircrafts are described in the initial phase of the thesis. In addition, description of the plane of interest Skyleader has been conducted, while along with the basic characteristics the focus is mainly on its wing and flap. The thesis continues with detailed CFD method calibration task, which is mostly focused on the basic turbulent models comparison. The optimization task conducted within this diploma thesis includes CFD calculations to determine aerodynamic characteristics of the flap provided by Jihlavan company, and subsequent determination of its optimal position. An important part of this thesis is also evaluation of the load and strength of the flap in previously determined optimal position. At the end, the strength and fly tests of the flap in the new position are described.
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Kohont, Alexander, and Roger Can Isik. "TERMISKT SMARTA HANTERINGSSYSTEM FÖR LITIUMJONBATTERIER : Analys av litium-jonbatteriets termiska beteende." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-55065.
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Batteries play an important role in a sustainable future. As the development for better andsmarter batteries continues, new areas of use emerge boosting its demand. Controlling thetemperature of a battery cell is a vital objective to ensure its longevity and performance. Bothcooling and heating methods can be applied to keep the temperature within a certain rangedepending on its need. This study will review the technical aspects of lithium-ion batteries,observe the different thermal management systems and cooling methods, and lastly examinethe required cooling flow needed for a battery cell to prevent its temperature from rising tocritical levels during its discharge. Using CFD ANSYS Fluent as a simulation tool, the resultsshow that different charging rates, in terms of C-rate, require different rates of mass flow tocontrol the temperature. Simulating the cell with natural convection, the cell peaks at hightemperatures even at lower C-rates, reaching up to 36,4°C and 48,8°C for 1C and 2C,respectively. Applying the cooling method with a flow rate of 0,0077kg/s reduces thetemperature significantly, resulting in temperatures of 26,95°C and 31,27°C for 1C and 2C,respectively.
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Shindle, Bradley W. "Computational Investigations of Polymer Sheet Breakup for Optimization of Devolatilization Processes in Steam Contactors." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1509379799347531.
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Sjösten, William, and Victor Vadling. "CFD Simulations of Flow Characteristics of a Piano Key Weir Spillway." Thesis, Uppsala universitet, Elektricitetslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-414861.
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Comprehensive rehabilitation projects of dam spillways are made in Sweden, due to stricter dam safety guidelines for their discharge capacity. The Piano Key Weir (PKW) is an innovative design which has proven effective through several renovation projects made in many countries including France. In this study we investigate the flow patterns around a prototype PKW, located in Escouloubre dam in southern France, with numerical simulations through three different flow cases in Ansys Fluent. A computational domain containing the PKW is created in the CAD software Ansys SpaceClaim for the simulations. Three polyhexcore meshes are further generated using Ansys Fluent Meshing. The three flow cases are then simulated with a Reynolds-averaged Navier-Stokes (RANS) model, coupled with realizable k-epsilon and volume of fluid models. Through an assessment of the discretization error between three meshes, a relative error of one percent is obtained for the discharge rate. The numerical results are qualitatively compared with results from previously conducted physical experiments on this PKW. The RANS model does not capture the water surface undulations (due to turbulence) around the PKW. The effects from under modelled surface undulations are alleviated by inserting an air vent to the PKW, which results in a flow behaviour in good agreement with the physical experiments. Through this alteration, water discharge rates are computed with a maximum discrepancy of five percent compared with the corresponding experimental values. A large eddy simulation should be conducted in the future, to bring further light on air exchange and water interaction phenomena present in the PKW flow pattern.
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Allen, Jeremy L. "The Effect of Baffle Arrangements on Flow Uniformity in a Manifold for a Unique Solid Oxide Fuel Cell Stack Design." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1320851931.
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Boga, Gabriele. "Analisi aerodinamica preliminare di un veicolo alimentato ad energia solare." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/14285/.
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L’obiettivo di questo lavoro è lo studio della variazione dei carichi aerodinamici per piccole variazioni della geometria su un veicolo da competizione ad energia solare. Questa analisi si inserisce nell’ottimizzazione aerodinamica di dettaglio. Il veicolo oggetto di studio è Emilia IV, auto sviluppata dal team Unibo Onda Solare. L’attività si è svolta tramite lo studio di tre configurazioni ottenute inclinando la parte superiore del veicolo originale di +2° e di -2°. Per le simulazioni fluidodinamiche è stato utilizzato il codice di calcolo commerciale Ansys Fluent. Le simulazioni sono state condotte con una velocità del flusso indisturbato di 20 m/s e con un numero di Reynolds calcolato sulla lunghezza della vettura di 6 milioni. Per la modellazione della turbolenza è stato utilizzato il modello k-epsilon realizable. È stato considerato uno strato limite turbolento per tutta la lunghezza del veicolo. La validazione del modello utilizzato è stata effettuata sulla geometria originale di Emilia IV tramite dati ottenuti precedentemente da simulazioni condotte con codici di calcolo Open Source (Open Foam) da ricercatori della Facoltà di Ingegneria di Forlì. La validazione della mesh è stata effettuata tramite simulazioni con quattro griglie di calcolo con numero di elementi crescente per verificarne la convergenza. Il numero di elementi della mesh definitiva è di 8 milioni composta da celle tetraedriche e da celle prismatiche. Si è data particolare rilevanza al coefficiente di resistenza delle tre vetture. Il modello utilizzato ha fornito risultatati sufficientemente accurati al fine di questo lavoro. La geometria originale si è dimostrata essere la più efficiente in termini di resistenza aerodinamica.
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Ringe, Shivansh. "Designing of One Directional Wave Tank." Thesis, Uppsala universitet, Institutionen för elektroteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-423335.
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Uppsala University wants to make a wave tank which can be used for experiment and education purpose. The project's aim is to get design parameters required to make a wave tank, design the wave tank, to do analysis on wave parameters taken from results and analysis of material which can be used to construct it. This project is an extension of the project called Numerical Wave Tank Design in which a literature study on existing wave research facilities was done [1]. The data from this project is used to get the dimensions of the wave tank. A study on hydrodynamics and wave theory is done to understand flow motion and wave generation. Ansys Fluent is used for Computational Fluid Dynamics (CFD). The software is used to test the wave tank with different wave absorber and observe if a good quality wave with a minimal reflection can be generated in the wave tank of chosen dimensions. Four models were created for testing wave absorber of different shapes. The setup for all the models was kept the same for comparison purposes. Waves generated from CFD were later compared with the theoretical waves obtained from wave theory. The next part was to model the wave tank in Computer-Aided Design (CAD) software, SolidWorks. The stress and strain analysis was done on the walls and support beam of the wave tank to know if the structure can sustain the water when fully filled. After creating static simulation different scenarios were performed on the beam and stand of the wave tank. The design study on these parts was compared to see which case provides a more optimal solution. It was found out that wave absorber having an elevation of 18.4 degrees, i.e., 1:3 slope provides the highest wave height for the given parameter and dimensions of the wave tank. In wave analysis, it was seen that wave height is proportional to the stroke length, water depth is proportional to wave height and time period is inversely proportional to the wave height. Cast stainless steel is used in a wave tank as it is cheap, reliable and robust. It was found out that the support beam 0.015 m thick is enough, although it can be increased to 0.02 m. In the design study of the wave tank stand, it was found out that a leg distance of 0.78 m and a leg width of 0.06 m is sufficient to withstand the weight of the wave tank.
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Cancela, Rodriguez Eva Maria. "Optimization of CFRP components positioning inside the autoclave through CFD simulations." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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Carbon fiber reinforced polymers (CFRP) show an excellent balance between thermomechanical properties and low density, leading them to be the material of choice in many applications. In the past years, the use of polymer matrix composites has significantly increased in the aerospace, automotive and naval sectors. Correspondingly, the requirements on high performance and quality keep increasing with the market demand. This generates a big concern on material properties along with the production of a large number of components, minimizing cycles’ time.
This document deals with the optimization of the distribution of composite components inside the autoclave obtaining therefore, the best configuration in order to achieve fair properties in all the elements in the shortest time possible. This study has been done along with the company Eligio Re Fraschini S.p.A., analyzing one of their autoclaves. The aim is to find the best configuration for a given repetitive production.
The optimization procedure that has been followed consisted in, for each of the three different productions considered, assess a set of models representing contrasting scenarios, in order to understand the flow behaviour and find the optimal distribution. The outcomes for the different locations are obtained through simulations performed with Ansys Fluent, a computational fluid dynamic (CFD) software; the ideal configuration is the one maximizing the heat transfer through all the components, in an homogeneous way.
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Šimberský, Michal. "Simulace proudění vzduchu a stanovení trvalé tlakové ztráty pro normalizovanou clonu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220891.
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This master’s thesis deals with the simulation of flow through the normalized orifice plate. There is described flow measurement with flowmeters, which reduces the cross-section of the pipe and causes the pressure difference before and after the flowmeter. Following is a description methods of modeling of turbulent flow and a description of software for the simulation of flow from the company Ansys. The theoretical part is followed a practical part, which is focused on determining the permanent pressure loss caused by the orifice plate and the verification of straight pipeline lengths between orifice and obstacle.
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Woldu, Yared, and Anton Fritz. "Using CFD to analyze thermal and optical influence on a zero pressure balloon at floating condition." Thesis, Luleå tekniska universitet, Rymdteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-69620.
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The ability to control the trajectory and understanding the atmospheric effects on the flight performance of a scientific high altitude balloon has long been an aspiring ambition. This thesis work analyses the thermal and optical environments at float using the simulation software, ANSYS FLUENT. The objectives for this thesis were to evaluate how the solar angle, sunshine factor and the ground emissivity altered the altitude for the balloon during floating condition in Steady-state simulations. A transient simulation was conducted to evaluate the diurnal cycle effects on the altitude of the balloon. The understanding of how the parameters influence the altitude will make it possible to autonomously route the balloon to desired altitudes where you have a favorable wind direction. Performing steady-state simulations showcased the significance of certain parameters. Different solar angles greatly influenced the temperature gradient on the balloon and hence a larger lifting force acted on the balloon when the sun was at its highest point. Varying the cloudiness mostly affected the maximum temperature distribution and did not affect the minimum temperature distribution. The steady-state simulations also indicated a limited but noticeable dependence on the ground emissivity. From the transient simulations it was further enhanced how great of influence the solar angle have, which was illustrated by running diurnal cycles. It was also apparent that there are great differences depending on the seasons. For future applications, it would be of interest to investigate the effects caused by wind velocities in the steady-state case. A comparative analytic solution should be performed in order to validate the simulation results.
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Dohnal, Miloslav. "Výpočtová analýza proudění v bubnové sušičce prádla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2014. http://www.nusl.cz/ntk/nusl-231275.
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The aim of this work is to create a computational model of radial industrial tumble dryers, to calculate and identify the amount of air that flows through the inside of the drum itself. The calculation will be performed via computational fluid dynamics (CFD). Furthermore, compile transient balance model of mentioned dryers. Perform simulation balance model and compare the results of simulations with experimental measurements. By comparing the experimental data and simulation to determine the degrees of freedom of balance model and evaluate their impact on the assembled transient model. For a better understanding of the drying process, there is constructed a system of differential equations describing heat and moisture within the material being dried on a simple model. In the section devoted to the computational analysis of fluid flow is analyzed existing geometry of the drum, which has a major impact on the flow of air inside the drum itself. Following describes how to simplify its complex geometry entering the computational fluid dynamics. Then, there is carried out a simulation of fluid flow inside the tumble dryers using MRF and Sliding Mesh models. Finally, there is an analysis of the data obtained and determined the average amount of air flowing through the drum itself. On the contrary, the aim of the work is not to create another text tool for students engaged in CFD theme.
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Hamberg, Micaela, and Signe Dahlin. "Numerical Study on Hydrodynamic Characteristics of Flood Discharge Tunnel in Zipingpu Water Conservancy Project : Using RANS equations and the VOF model." Thesis, Uppsala universitet, Elektricitetslära, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-387206.
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To avoid the large amount of damage that floods can cause, spillway tunnels are used to control water levels. To ensure the safety of water transportation through spillway tunnels, the behaviour of the water throughout the tunnel is important to know. Physical experiments are time consuming and expensive, hence CFD simulations are a profitable option for investigating the performance of the spillway tunnel. In this project, simulations of water flow in a spillway tunnel were executed. A three dimensional model of the spillway tunnel in Zipingpu Water Conservancy Project was created in the software ANSYS Gambit. A coarse, middle and fine mesh with both hexahedral- and tetrahedral elements were also created for the model in ANSYS Gambit. The meshes were imported to ANSYS Fluent where the simulations, and a convergence analysis were made. The water flow was set to be described by the Reynolds-Averaged Navier-Stokes model, using the pressure solver, k-epsilon model and the VOF model. Physical experiments had previously been performed, and the simulated results were compared to these, in an attempt to find the parameters to replicate the experimental results to the greatest extent possible. The inlet velocity of the tunnel was known and the inlet boundary was set as a velocity inlet. The ceiling of the tunnel was set as a pressure inlet, the floor and walls were set as wall, and the outlet was set as pressure outlet. The simulated results showed similar behavior as the experimental results, but all differed from the experimental results. The grid convergence index, estimating the results' dependency on the mesh was 6.044 %. The flow was analyzed, and where the flow had unfavorable characteristics, such as a high cavitation number, the geometry of the spillway was altered in ANSYS Gambit to investigate if an improved geometry for the spillway tunnel could be found. The water flow in the revised geometry was simulated in ANSYS Fluent, and results showing flow with lower cavitation numbers was found.
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Karlíková, Adéla. "Modelling of flow and pressure characteristics in the model of the human upper respiratory tract under varying conditions." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413820.
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Cílem této diplomové práce je vytvořit 3D model horních dýchacích cest podle originálního modelu segmentovaného z CT dat, aplikovat různé podmínky na průtok vzduchu v modelu, a poté hodnotit změnu charakteristik rychlosti a tlaku. Model horních dýchacích cest byl vytvořen v prostředí softwaru ANSYS, který využívá výpočetní dynamiku tekutin, a byly použity Navier-Stokesovy rovnice pro modelování průtoku vzduchu v modelu. Nejprve byl vytvořen jednoduchý 2D model za účelem seznámení se s prostředím ANSYS. Dále byl zkonstruován 3D model horních dýchacích cest a byly modelovány charakteristiky rychlosti a tlaku za různých podmínek. Tyto podmínky zahrnují různé umístění a množství míst pro odběr vzorků v modelu a výběr různých kombinací vstupů. Nakonec byly prezentovány a hodnoceny výsledky spolu s ilustracemi modelů modelovaných za různých podmínek. 3D model lze považovat ze kompromis mezi výpočetní náročností a složitostí modelu a lze jej použít jako základ pro další výzkum.
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Acharya, Rutvika. "Investigation of Differences in Ansys Solvers CFX and Fluent." Thesis, KTH, Mekanik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-203937.
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This thesis aims at presenting Computational Fluid Dynamics studies conducted on an axisymmetric model of the Siemens SGT-800 burner using Ansys Fluent, Ansys CFX and Ansys ICEM. The goal is to perform a mesh study and turbulence model study for isothermal flow. The result will show the differences observed while using the two solvers by Ansys, Fluent and CFX. Two different meshes, A, coarse and B, optimal have been used for the mesh study. This will reveal the mesh dependency of the different parameters and if any differences are observed between the solver’s convergence and mesh independency performance. To further validate the mesh independency, a simplified test case is simulated for turbulent flow for 32 different cases testing the numerical algorithms and spatial discretization available in Ansys Fluent and finding the optimal method to achieve convergence and reliable results. Turbulence model study has been performed where k-ε, k-ω and k-ω Shear Stress Transport (SST) model have been simulated and the results between solvers and models are compared to see if the solvers’ way of handling the different models varies.Studies from this thesis suggest that both solvers implement the turbulence models differently. Out of the three models compared, k-ω SST is the model with least differences between solvers. The solution looks alike and therefore it could be suggested to use this model, whenever possible, for future studies when both solvers are used. For the models k-ε and k-ω significant differences were found between the two solvers when comparing velocity, pressure and turbulence kinetic energy. Different reasons for its occurrence are discussed in the thesis and also attempts have been made to rule out few of the reasons to narrow down the possible causes. One of the goals of the thesis was to also discuss the differences in user-interface and solver capabilities which have been presented in the conclusions and discussions section of the report. Questions that still remain unanswered after the thesis are why these differences are present between solvers and which of the solvers’ results are more reliable when these differences have been found.
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Plank, Jack R. "Nuclear Thermal Propulsion Cool-Down Phase Optimization Through Quasi-Steady Computational Analysis, and the Effect of Auxiliary Heat Removal Systems." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1618934609976051.
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Orlandi, Francesco. "Applicazione e Confronto di Modelli Computazionali Turbolenti per l'Analisi dei Fenomeni Fluidodinamici in Camera di Reazione di una Sorgente di Plasma Termico di Tipo ICP-RF per la Produzione di Nanoparticelle." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
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Il presente studio è stato realizzato per operare un confronto, in ambito CFD, tra diversi modelli di turbolenza applicati a una geometria ridotta di torcia al plasma industriale di tipo ICP-RF, basato sul modello PL-35 di Tekna Inc. Lo studio è stato svolto all’interno del software FLUENT utilizzando delle UDF per caratterizzare le proprietà termofisiche del plasma. Il primo metodo utilizzato è un k-epsilon modificato secondo Bolot, dal quale, dopo aver validato i campi delle grandezze caratteristiche e l’attendibilità dei risultati sulla base di studi precedenti, si è ottenuto un campo simmetrico e ben delineato di turbolenza stazionaria. Il confronto con un k-epsilon standard ha chiarito il fondamentale apporto del termine sorgente aggiuntivo di Bolot per modellare correttamente la turbolenza e fornire il giusto campo di temperatura. Si sono poi utilizzati due metodi LES, WALE e Dinamico, e confrontati i risultati. La fiamma di plasma è risultata più verosimilmente realistica ma i campi di temperatura sono risultati troppo elevati nella regione a più alta temperatura, ovvero in ingresso in camera di reazione. I LES fino all’entrata in camera di reazione risultano concordi col modello k-epsilon ma successivamente la modellazione del fenomeno turbolento porta ad una elevata dissipazione di energia cinetica turbolenta che porta a valori del campo di temperatura troppo elevati. L’utilizzo invece del k-omega e del RSM, che hanno fornito campi completamente irrealistici, ha dimostrato l’inutilità di utilizzare tali metodi per sistemi simili data l’inadeguatezza dei suddetti modelli per tali sistemi. Il confronto dei modelli LES col k-epsilon rende necessario la modifica di tali modelli in un futuro per poter integrare gli effetti correttivi del termine sorgente di Bolot nel termine Cs di questi, in modo da poter unire la correttezza del modello k-epsilon con la risoluzione e il realismo tipico di questi modelli.
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Čermák, Jakub. "Numerická analýza bio-mimetického konceptu řízení proudu na povrchu křídla." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-317186.
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V této diplomové práci je provedena optimalizace profilu křídla vybaveného elastickou klapkou umístěnou na horní straně profilu. Optimalizační proces je proveden s vyžitím CFD prostředků, konkrétně URANS metody. V prvních kapitolách je popsána historie vývoje křídla vybaveného pohyblivými klapkami. Práce pokračuje popisem a zdůvodněním volby numerické metody. Vytvoření geometrie a výpočetní sítě je krátce popsáno. V práci je také prezentována validace a verifikace dané výpočetní metody. Případová studie je zaměřena na profil LS(1)-0417mod vybavený 20%, 30% a 40% dlouhou, pevnou kalpkou na různých úhlech náběhu. Aerodynamická účinnost společně s proudovým polem je analyzována. Je provedena nelineární pevnostní analýza s využitím MKP programu za účelem vyhodnocení ohybové tuhosti a deformovaného tvaru elastické klapky tak, aby byly splněný podmínky nutné pro automatické vychýlení.
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Vivarelli, Simone. "Analisi della sezione di blowdown di un impianto di produzione di catalizzatori di Ziegler-Natta." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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Il presente lavoro di tesi è stato svolto presso il Centro Ricerche Giulio Natta appartenente allo stabilimento chimico di Basell Poliolefine Italia S.r.l., gruppo LyondellBasell, situato all’interno del Polo Chimico di Ferrara. Tale attività ha riguardato lo studio di aspetti di sicurezza relativi ad uno specifico reparto in cui ha luogo la produzione di catalizzatori Ziegler-Natta. In particolare è stata posta l’attenzione sulla sezione di blowdown, deputata al trattamento delle correnti di materia che si possono generare in situazioni di emergenza.
L’obiettivo principale del lavoro di tesi consiste nella valutazione dell’adeguatezza della sezione di blowdown attualmente presente presso l’impianto, con particolare riferimento alle apparecchiature installate con lo scopo di abbattere le eventuali sostanze pericolose provenienti dai dispositivi di sicurezza. In aggiunta a ciò, è parte integrante dell’obiettivo della tesi la valutazione degli eventuali effetti dannosi derivanti della dispersione in atmosfera di tali sostanze, anche per mezzo di strumenti offerti dalla fluidodinamica computazionale.
Una prima parte del lavoro svolto ha riguardato la raccolta delle informazioni concernenti le apparecchiature attualmente esistenti in reparto, le condizioni operative e le sostanze coinvolte. Successivamente sono stati definiti i principali eventi incidentali che possono portare all’attivazione dei dispositivi di sicurezza.
Al fine di simulare la risposta del sistema nei confronti delle situazioni di emergenza, è stata svolta una modellazione delle apparecchiature che compongono la sezione di blowdown, orientata ove possibile nei confronti dei principali software di process engineering.
Infine è stata modellata la dispersione dal camino delle correnti non abbattute, in un primo momento tramite l’utilizzo di software tradizionali mentre in un secondo momento ricorrendo a metodi di fluidodinamica computazionale per una valutazione più accurata di tale fenomeno.
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Dvořák, Petr. "Optimalizace štěrbinové vztlakové klapky letounu." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228790.
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The main objective of this diploma thesis is to optimize the high lift device on the wing of the Phoenix Air U-15 ultralight aircraft, so that it complies with the UL-2 regulation regarding the stalling speed – 65 KPH. This is fulfilled by optimization of the slotted flap position. Methods used include the Response Surface Method and the Computational Fluid Dynamics approach – namely Ansys Fluent v6 software package. Furthermore, the paper deals with take-off flap optimization and construction of the flap deflection mechanism.
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Brogren, Felix, and Peter Gustafsson. "VIBRATION ANALYSIS OF THE FLUE GAS FAN IN MÄLARENERGI’S UNIT 6 : Troubleshooting using CFD simulations in ANSYS to locate the origin of the vibration spikes and suggest solutions for a more optimized performance." Thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-40030.
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The purpose of this study is to investigate the flue gas fan in Mälarenergi’s Unit 6 and try to find what is causing the vibrations increase. The Fast Fourier transform (FFT) method was used for this degree project. A comparison was made with previous studies using FFT in order to pinpoint the source of the problem with vibrations. After a possible source had been identified, a computational fluid dynamics (CFD) simulation was performed using ANSYS to visualize the problem. Two cases were simulated using two different turbulence models: the K-epsilon model and the Large-eddy simulation (LES) model. The result from the CFD simulations was compared with previous studies that used similar turbulence models. The flue gas fan’s high vibrations are most likely flow-induced. The simulation result indicates that LES model performed better than the Kepsilon model. The lack of validation in this degree work means that it is hard to know the accuracy of the model. Based on the simulation results the most promising solution seems to be inlet straighteners.Syftet med studien är att undersöka rökgasfläkten i Mälarenergis Unit 6 och att försöka hitta vad som orsakar vibrationsökningarna. Fast Fourier transform metoden har används i detta examensarbete. En jämförelse har gjorts med tidigare studier som använt FFT metoden för att kunna urskilja källan till vibrationsproblemet. Efter en rimlig källa hittades så utfördes en CFD-simulering i ANSYS för att visualisera problemet. Två fall simulerades med två olika turbulensmodeller: K-epsilon modellen och Largeeddy simulation modellen. Resultatet från CFD-simuleringarna jämfördes med tidigare studier som använt liknande metoder. Rökgasfläktens höga vibrationer är med störst sannolikhet flödesinducerad. Simuleringsresultatet indikerar att LES modellen utfördes bättre än Kepsilon modellen. Då det saknas en validering i form av flödesmätningar så är det svårt att säga hur lik modellen är med verkligheten. Baserat på resultatet från simuleringarna så verkar inloppsgaller vara den mest lovande lösningen.
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"Proton Exchange Membrane Fuel Cell Modeling and Simulation using Ansys Fluent." Master's thesis, 2011. http://hdl.handle.net/2286/R.I.8956.
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abstract: Proton exchange membrane fuel cells (PEMFCs) run on pure hydrogen and oxygen (or air), producing electricity, water, and some heat. This makes PEMFC an attractive option for clean power generation. PEMFCs also operate at low temperature which makes them quick to start up and easy to handle. PEMFCs have several important limitations which must be overcome before commercial viability can be achieved. Active areas of research into making them commercially viable include reducing the cost, size and weight of fuel cells while also increasing their durability and performance. A growing and important part of this research involves the computer modeling of fuel cells. High quality computer modeling and simulation of fuel cells can help speed up the discovery of optimized fuel cell components. Computer modeling can also help improve fundamental understanding of the mechanisms and reactions that take place within the fuel cell. The work presented in this thesis describes a procedure for utilizing computer modeling to create high quality fuel cell simulations using Ansys Fluent 12.1. Methods for creating computer aided design (CAD) models of fuel cells are discussed. Detailed simulation parameters are described and emphasis is placed on establishing convergence criteria which are essential for producing consistent results. A mesh sensitivity study of the catalyst and membrane layers is presented showing the importance of adhering to strictly defined convergence criteria. A study of iteration sensitivity of the simulation at low and high current densities is performed which demonstrates the variance in the rate of convergence and the absolute difference between solution values derived at low numbers of iterations and high numbers of iterations.Dissertation/Thesis
M.S.Tech Chemistry 2011
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PENG, GUEI-DE, and 彭桂德. "Method and Feasibility of Simulating the Distribution of Suspended Particles in Platform of MRT Underground Station Using CFD-ANSYS FLUENT." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/48c3x5.
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碩士明志科技大學
環境與安全衛生工程系環境工程碩士班
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The Mass Rapid Transit System of the Metropolitan Area is inseparable from the life of modern people. The underground MRT station is not easy to ventilate due to its closure property, which will increase the exposure risk and harm of the suspended particles of passenger. Therefore, how to establish a more comprehensive, rapid and reasonable numerical analysis method is one of the topics that need to be breakthrough in the Metropolitan Mass Rapid Transit System. In view of this, this paper uses ANSYS FLUENT v17.2 to simulate the domestic MRT underground station. The study set up a dynamic simulation of the electric railcar train to observe the flow field changes and the diffusion of PM10. And according to the original MRT underground station model (Case1), a Pressure release bypass channel model (Case2) is added. Finally, the difference between the two models for the overall flow field wind speed and PM10 is compared. According to the simulation results, FLUENT can reasonably simulate the piston effect, wake effects and wind field distribution generated by the electric railcar train. Regardless of whether or not the pressure release bypass channel is provided, the PM10 in the front section of the platform layer diffuses farther and wider, and the higher PM10 concentration distribution appears in the middle of the platform layer, while the rear of the platform layer is the least affected area. In addition, in the front, middle and back sections of the platform, the Case2 model reduced the average PM10 concentration of Case1 model by 6.11%, 3.66% and -0.95%. The results show that the setting of the pressure release bypass channel can effectively reduce the PM10 concentration in the front and middle sections. It was also found that the cross-section(height 1.6m) of the platform center, P1 and P2 detection points located in the front section of the platform, the average PM10 concentration of the Case2 model compared with the Case1 model was reduced by 13.68 μg/m3 (39.67%) and 6.43 μg/m3 (18.61%). It indicates that the setting of the pressure release bypass channel can effectively reduce the PM10 concentration in the front section of the platform. However, the concentration of PM10 is slightly increased in the rear section of the platform. Overall, the setting of pressure relief bypass channel can reduce a certain degree of PM10 concentration distribution. Finally, this paper finds that, in the absence of other external forces, when the electric railcar train is driven at 10m/s, the kinetic energy given by the piston wind to PM10 is not enough to be transmitted to the tunnel. However, if the electric railcar train travels faster or skip-stop, it will be possible to spread the PM10 to the concourse level.
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"CFD Analysis of Wind Power Potential Across Rooftop Gaps of Tall Buildings." Master's thesis, 2017. http://hdl.handle.net/2286/R.I.44061.
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abstract: This study uses Computational Fluid Dynamics (CFD) modeling to analyze the
dependence of wind power potential and turbulence intensity on aerodynamic design of a
special type of building with a nuzzle-like gap at its rooftop. Numerical simulations using
ANSYS Fluent are carried out to quantify the above-mentioned dependency due to three
major geometric parameters of the building: (i) the height of the building, (ii) the depth of
the roof-top gap, and (iii) the width of the roof-top gap. The height of the building is varied
from 8 m to 24 m. Likewise, the gap depth is varied from 3 m to 5 m and the gap width
from 2 m to 4 m. The aim of this entire research is to relate these geometric parameters of
the building to the maximum value and the spatial pattern of wind power potential across
the roof-top gap. These outcomes help guide the design of the roof-top geometry for wind
power applications and determine the ideal position for mounting a micro wind turbine.
From these outcomes, it is suggested that the wind power potential is greatly affected by
the increasing gap width or gap depth. It, however, remains insensitive to the increasing
building height, unlike turbulence intensity which increases with increasing building
height. After performing a set of simulations with varying building geometry to quantify
the wind power potential before the installation of a turbine, another set of simulations is
conducted by installing a static turbine within the roof-top gap. The results from the latter
are used to further adjust the estimate of wind power potential. Recommendations are made
for future applications based on the findings from the numerical simulations.Dissertation/Thesis
Masters Thesis Mechanical Engineering 2017
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Hansraj, Harsh Shantukumar. "Análise CFD de modelos de turbulência durante a combustão no motor CFM56-3." Master's thesis, 2019. http://hdl.handle.net/10400.6/8946.
Full textAbstract:
Atualmente o motor CFM56 é um dos modelos de motor mais usado na indústria aeronáutica, principalmente na aviação civil. Como tal, a melhoria das suas características a nível de rendimento, eficiência ou emissões de gases é fundamental. Com este trabalho é pretendido analisar diversos modelos de turbulência durante a combustão que permitem uma melhor perceção de alguns problemas e a sua possível resolução. Para esta dissertação foi utilizado o ficheiro STL da digitalização da câmara de combustão fornecida pelo orientador deste trabalho. No caso numérico é apenas usada um quarto da câmara de combustão devido à sua simetria permitindo um menor esforço computacional durante as simulações e o combustível utilizado na combustão é o Jet-A. A malha utilizada foi desenhada no software HELYX OS e as simulações numéricas são efetuadas no ANSYS Fluent 16.2. A atomização de combustível não é considerada neste estudo devido ao seu elevado grau de complexidade. São analisados os modelos k-?, k-?, RSM e LES sendo que neste último são utilizadas condições iniciais resultantes do modelo k-?. Todas as entradas de ar e os injetores são definidos como mass-flow inlets e a saída da câmara de combustão é definida como pressure outlet. Os resultados obtidos estão em concordância com alguns dados experimentais de referência presentes na Emissions Data sheet da ICAO. Entre os modelos analisados observou-se que em geral, apesar do seu elevado custo computacional, o modelo LES é o que melhor identifica as diversas zonas da câmara de combustão. No entanto os modelos RSM e k-? revelaram ser bastante úteis na observação da distribuição da emissão de alguns gases durante a combustão. Conclui-se que o modelo LES apresenta os melhores resultados, mas a escolha do modelo mais indicado pode variar consoante as condições de fronteira e tipo de escoamento do caso de estudo a analisar.Nowadays the CFM56 engine is one of the most widely used engine models in the aviation industry, especially in civil aviation. Therefore, improving its characteristics in terms of performance, efficiency or gas emissions is crucial. With this work it is intended to analyse several turbulence models during the combustion allowing a better understanding of some problems and their possible resolution. For this dissertation the STL file of the combustion chamber digitization was provided by the supervisor of this work was used. In the numerical case only a quarter of the combustion chamber is used due to its symmetry allowing a less computational effort during the simulations and the fuel used in combustion is Jet-A. The mesh used was designed in HELYX OS software and numerical simulations are performed in ANSYS Fluent 16.2. Fuel atomization is not considered in this study due to its high degree of complexity. The models k-?, k-?, RSM and LES are analysed and in the latter, the initial conditions resulting from the k-? model are used. All the air inlets and injectors are defined as mass-flow inlets and the combustion chamber outlet is defined as pressure outlet. The results obtained show reasonable agreement with some experimental reference data present in the ICAO Emissions Data Base. Among the analysed models it was observed that in general, despite its high computational cost, the LES model is the one that best identifies the various zones of the combustion chamber. However, the RSM and k-? models proved to be very useful in observing the emission distribution of some gases during combustion. It is concluded that the LES model gives the best results, but the choice of the most suitable model may vary depending on the boundary conditions and flow type of the case study to be analysed.
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Guedes, Vítor Hugo Moura. "Airflow simulation in a horizontal closed refrigerated display cabinet." Master's thesis, 2019. http://hdl.handle.net/1822/65342.
Full textAbstract:
Dissertação de mestrado em Mechanical EngineerRefrigeration equipment has become essential in several areas, especially in food preservation. In the last few years, closed refrigeration equipment becomes more popular because its consumption is much lower compared to the open ones. The work of this study focuses on the analysis of the cold air flow that traverses the equipment, knowing the external conditions. For this purpose, CFD ANSYS Fluent program was used. This uses the finite volumes technique to solve the equations of conservation of mass, momentum and energy. In the first part of the work, it was made a set of 2D simulations in which several parameters were studied. Firstly, the most appropriate mesh dimension was analysed (using only quadrilateral elements), then a comparison was made between different types of exits and turbulence models. To finish the 2D study products were introduced in the geometry with different dimensions, acting as obstacles to the fluid flow. Concerning the influence of the parameters, it can be concluded that the most predominant is the temperature in the lower zone near the evaporator. The heat flux near the wall and the influence of the lamps on the geometry with products affect punctually, not being reflected in other geometry zones significantly. The increased perforated area in the lower back allows greater ventilation in the lower back, however the temperature increases slightly. In the geometry with products, it can be concluded that the 2D geometry used is very limiting.
Os equipamentos de refrigeração tornaram-se essenciais em várias vertentes, especialmente na conservação de alimentos. Nos últimos anos os equipamentos de refrigeração fechados têm ganho destaque devido ao seu consumo ser muito inferior comparativamente com os abertos. O estudo centra-se na análise do escoamento de ar frio que percorre o equipamento, tendo em conta as condições exteriores. Para este efeito recorreu-se ao uso do programa CFD ANSYS Fluent. Este usa a técnica de volumes finitos na solução das equações de conservação da massa, momentum e energia. Na primeira parte do trabalho fez-se um conjunto de simulações 2D em que foram estudados vários parâmetros. Primeiramente, foi analisada a dimensão da malha mais adequada (com apenas elementos quadriláteros); de seguida, foi feita uma comparação entre diferentes tipos de saídas e modelos de turbulência. Para terminar o estudo 2D foram colocados produtos de diferentes dimensões, atuando como obstáculos ao escoamento. Quanto à influência dos parâmetros, pode concluir-se que o mais predominante é a temperatura na zona inferior junto ao evaporador. O fluxo de calor junto à parede e a influência das lâmpadas na geometria com produtos afetam pontualmente, não se refletindo noutras zonas geometria de uma forma evidente. O aumento da área perfurada nas costas na zona inferior permite uma maior ventilação nessa zona, contudo a temperatura aumenta ligeiramente. Quanto à geometria com produtos, pode concluir-se através dos resultados que a geometria 2D utilizada é bastante limitadora.
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Oliveira, Jonas Miguel Pires. "CFD Analysis of the Combustion of Bio-Derived Fuels in the CFM56-3 Combustor." Master's thesis, 2016. http://hdl.handle.net/10400.6/6527.
Full textAbstract:
A CFD simulation of a CFM56-3 combustor burning Jet-A and a 100% blend of biofuels, is performed.
It is intended to evaluate the viability of these biofuels in a combustion point of view,
by analysing the emissions and the energy extracted when burning these through ICAO's LTO
cycle, so that these biofuels can be considered as a future civil aviation fuel. The three biofuels
considered for this study were extracted from jatropha seeds, algae and sunflower. Due to the
confidentiality that exits among GTE manufacturers, it is very difficult to obtain the blueprint
of any given part of a GTE, and the combustor in study was no exception. Fortunately TAP kindly
provided an operational CFM56-3 combustor, and with the aid of a 3D scanner, named Spider
from Artec group, which belongs to UBI, it was possible to create a 3D model of the combustor.
From this 3D model, an STL file can be exported, and then imported into CATIA V5, which is the
software chosen to perform the CAD. All of the relevant parts of the combustor is represented,
which include the primary and secondary swirlers, fuel injectors, cooling holes, walls and the
dome; only one quarter of the combustor was used for the numerical study due to the existing
symmetry, and due to the fact that within the existing 20 fuel injectors, there are four of
them that inject the fuel with a richer mixture. The numerical mesh is created using HELYX-OS
and the commercial software ANSYS Fluent 15.0 is used to perform the numerical study. Due
to the complexity of this study, the atomization of the fuel was not considered. The viscous
model used is the RSM; all of the air-inlets as well as the fuel injectors are defined as mass-flow
inlets, and the exit of the combustor is defined as a pressure-outlet. The final results show
reasonable agreement with the reference values presented by ICAO, when Jet-A is combusted,
representing an error in general very low. Among all of the fuels simulated, it was proved that
increasing the power produced higher NOx and lower UHC; however an unexpected behaviour
of CO emission decrease with a power increase, was predicted. The biofuel that presented the
best performance in ICAO's LTO cycle regarding NOx, CO and UHC emissions was sunflower
biofuel, as these emissions were lower when compared to all of the fuels. Jatropha biofuel
presented the highest CO2 reduction, representing a 20% decrease from Jet-A, and the energy
extracted represented a minimal decrease of 6% when compared to the same fuel. Overall, it
can be concluded that the biofuels studied have the potential to replace kerosene, and despite
more biofuel has to be burned to produce the same amount of energy as Jet-A, a significant
reduction in emissions is predicted.Uma simulação CFD é realizada numa câmara de combustão do motor CFM56-3, usando como combustíveis Jet-A e uma mistura de biocombustíveis a 100%. É pretendido avaliar a viabilidade destes biocombustíveis num ponto de vista da combustão, ao analisar as emissões e a energia extraída quando estes combustíveis são injetados, a fim de que estes biocombustíveis possam ser considerados como uma possibilidade de futuros combustíveis para a aviação comercial. Os três biocombustíveis que foram considerados para este estudo, são extraídos de sementes da planta jatropha, de algas e de girassol. Devido à confidencialidade que reina entre as empresas de manufatura de turbinas a gás, é muito difícil obter o blueprint de qualquer parte de uma turbina a gás, e a câmara de combustão em estudo não foi exceção. Felizmente a TAP gentilmente cedeu uma câmara de combustão ainda em serviço, na qual foi possível realizar um scan 3D, com recurso ao scanner pertencente à UBI, denominado de Spider da Artec Group. A partir deste modelo 3D, um ficheiro STL pôde ser exportado, e depois importado para o CATIA V5, que por sua vez foi o software escolhido para efetuar o CAD. Todas as partes da câmara de combustão relevantes para o estudo são representadas, onde estão incluídos os swirlers primário e secundário, os injetores de combustível, os orificios para arrefecimento, as paredes e o dome; apenas um quarto da câmara de combustão é usado para o estudo numérico devido à simetria existente, e devido ao facto que dos 20 injectores de combustível presentes, existem 4 em que é injetado uma mistura mais rica. A malha numérica é criada com recurso ao HELYX-OS, e o software comercial ANSYS Fluent 15.0 é usado para efetuar o estudo numérico. Devido à complexidade deste estudo, a atomização do combustível não é considerada. O modelo viscoso usado é o RSM; todas as entradas de ar, bem como os injetores de combustível são definidos como mass-flow inlets, e a saída da câmara de combustão é definida como um pressure-outlet. Os resultados finais estão razoalmente de acordo com os dados de referência apresentados pela ICAO, quando Jet-A é queimado, apresentando um erro no geral muito reduzido. Entre todos os combustíveis simulados, foi provado que aumentando a potência resultava num aumento de emissões NOx e num decréscimo de UHC's; contudo um comportamento inesperado de uma redução de emissões CO com o aumento da potência, foi verificado. O biocombustível que apresentou os melhores resultados ao longo de todo o ciclo de potência da ICAO, com respeito às emissões NOx, CO e UHC, foi o proveniente de girassol, uma vez que foi previsto valores de emissões inferiores, quando comparados com os restantes combustíveis. O biocombustível proveniente de jatropha foi o que apresentou uma maior redução de emissões CO2, representando um decréscimo de 20% comparando com o de Jet-A, e a energia extraída representou um menor decréscimo de 6% quando comparado com o mesmo combustível. No geral pode ser concluído que os biocombustíveis estudados têm o potencial de substituir a querosene, e apesar de que um maior consumo é exigido aos biocombustíveis, de forma a produzir a mesma energia que Jet-A, uma redução significativa de emissões é prevista.
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Obed, Samuelraj I. "Micro-Blast Waves." Thesis, 2011. http://hdl.handle.net/2005/2375.
Full textAbstract:
The near field blast–wave propagation dynamics has been a subject of intense research in recent past. Since experiments on a large scale are difficult to carry out, focus has been directed towards recreating these blast waves inside the laboratory by expending minuscule amounts of energy(few joules),which have been termed here as micro–blast waves. In the present study, micro-blast waves are generated from the open end of a small diameter polymer tube (Inner Diameter of 1.3 mm)coated on its inner side with negligible amounts of HMX explosive (~18 mg/m), along with traces of aluminium powder. Experimental, numerical, and analytical approaches have been adopted in this investigation to understand the generation and subsequent propagation of these micro–blast waves in the open domain. Time–resolved schlieren flow visualization experiments, using a high speed digital camera, and dynamic pressure measurements (head–on and side–on pressures) have been carried out. Quasi one dimensional numerical modeling of the detonation process inside the tube, has been carried out by considering the reaction kinetics of a single(HMX) reaction to account for the reaction dynamics of HMX. The one dimensional numerical model is then coupled to a commercial Navier– Stokes equation solver to understand the propagation of the blast wave from the open end of the tube. A theory that is valid for large scale explosions of intermediate strength was then used for the first time to understand the propagation dynamics of these micro–blast waves. From the experiments, the trajectory of the blast wave was mapped, and its initial Mach number was found to be about 3.7. The side–on overpressure was found to be 5.5 psi at a distance of 20 mm from the tube, along an axis, offset by 30 mm from the tube axis. These values were found to compare quite well with the numerically obtained data in the open domain. From the numerical model of the tube, the energy in the blast wave was inferred to be 1.5 J. This value was then used in the analytical theory and excellent correlation was obtained, suggesting the exciting possibility of using such theories, validated for large-scale explosions, to describe these micro–blasts. Considering the uncertainties in the approximate model, a better estimate of energy was obtained by working back the energy(using the analytical model) from the trajectory data as 1.25 J. The average TNT equivalent, a measure of its strength relative to a TNT explosion, was found to be 0.3. A few benchmark experiments, demonstrating the capability of this novel blast device have also been done by comparing them against the extant large–scale explosion database, suggesting the possibility of using these micro–blast waves to study certain aspects of large–scale explosions.
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Quintal, Dinarte José França. "Desenvolvimento e Otimização de Sensores para Ensaio do Motor CFM56-3." Master's thesis, 2018. http://hdl.handle.net/10400.6/8321.
Full textAbstract:
O projeto apresentado neste documento resultou de uma parceria entre a Universidade da Beira Interior e a TAP Manutenção e Engenharia, e teve por objetivo o desenvolvimento de novas soluções de instrumentação para ensaio do reator CFM56-3. Assim, e considerando as estações aerodinâmicas cujos principais parâmetros são desconhecidos ou medidos esporadicamente por falta de instrumentação adequada, o autor optou por centrar-se na obtenção de dados fiáveis de pressão e temperatura na estação aerodinâmica 25. Nesse sentido, e partindo da sonda de pressão e temperatura TP25, adquirida à CFMI e inutilizada face aos problemas estruturais e de instalação apresentados, iniciou-se o presente trabalho, que se desenvolveu em duas etapas.
Numa fase inicial, a sonda TP25 foi descrita em detalhe. Em seguida, e de forma a resolver as principais debilidades da ferramenta, apresentou-se um conjunto de propostas, as quais foram submetidas a uma análise comparativa de onde se obteve a solução de adaptação mais adequada aos requisitos do projeto. Assim, procedeu-se à criação de um primeiro exemplar, o qual sofreu alguns ajustes tendo em vista o aperfeiçoamento do processo de instalação no motor. Finalmente, obteve-se um protótipo otimizado, que partindo da sonda TP25 original, integra tecnologia atual e de fácil manuseamento, suportada por uma estrutura que atesta a consistência do conjunto. As melhorias introduzidas pela modificação proposta, permitem atingir os objetivos delineados, na medida em que a sonda de pressão e temperatura com uma nova interface integrada, agora mais robusta, fiável e funcional, pôde retornar ao serviço no banco de ensaios, contribuindo para a monitorização de desempenho do reator CFM56-3.
Depois de concluída a primeira etapa do trabalho, na qual se obteve uma solução definitiva para a reparação da sonda TP25, foi realizada uma simulação CFD no Inter-Compressor Duct do reator CFM56-3, a qual possibilitou a recriação das condições do escoamento considerando, ou não, a presença da sonda em referência. Através da aplicação da ferramenta computacional desenvolvida, pretende-se determinar a influência da forma aerodinâmica da sonda nas medições de pressão e temperatura, e avaliar a necessidade de proceder a alterações na configuração da mesma, como condição para a otimização do seu desempenho. Inicialmente, procedeu-se ao dimensionamento in loco da estrutura envolvente do Inter-Compressor Duct, cujas informações técnicas de relevo são mantidas em sigilo pelo fabricante. Posto isto, e recorrendo ao software CATIA V5, obtiveram-se as geometrias dos seguintes componentes: Fan Frame, VBV, Scoop e Sonda TP25, fundamentais na definição da região de fluido com a sonda instalada (ICD Air Volume) e em condições de escoamento não perturbado (ICDAV Without Sensor). A malha aplicada a cada um dos domínios do problema foi desenvolvida com recurso ao HELYX-OS, e o software ANSYS Fluent 16.2 foi utilizado na realização do estudo numérico. Aplicaram-se dois modelos de viscosidade, o Standard K-e e o Realizable K-e. Relativamente às condições fronteira, a descarga do Booster (entrada do domínio) foi definida como Mass Flow Inlet, a entrada do HPC (saída do domínio) foi definida como Pressure Outlet, e as demais superfícies, incluindo os elementos sensores da sonda (ICD Air Volume), como fronteira do tipo Wall. Após concluídas as simulações e validado o modelo, obtiveram-se as distribuições dos principais parâmetros termodinâmicos ao longo dos domínios considerados. Os resultados alcançados comprovaram a interferência do corpo da sonda TP25 sobre as características do escoamento, pelo que a sua influência foi quantificada por intermédio do erro de medição de pressão e temperatura, o qual permaneceu abaixo dos 5% e 1.5%, respetivamente. Pôde concluir-se então, que as medições obtidas no Inter-Compressor Duct, não estando imunes ao erro, garantem uma monitorização adequada dos principais parâmetros termodinâmicos do motor. Deste modo, não se justifica a otimização da forma aerodinâmica da sonda TP25, dado que as melhorias resultantes dificilmente justificarão os custos associados ao desenvolvimento de um novo protótipo.The project presented in this document is the result of a partnership between the University of Beira Interior and TAP Maintenance & Engineering and aimed to develop new instrumentation solutions for the CFM56-3 engine testing. Thus, considering the aerodynamic stations whose main parameters are unknown or sporadically measured due to lack of adequate instrumentation, the author chose to focus on obtaining reliable data of pressure and temperature in the aerodynamic station 25. Therefore, and starting from the temperature and pressure probe TP25, acquired from CFMI and rendered useless due to the structural and installation problems that were continuously brought up, the present work was started and developed in two complementary stages. At an early stage of the work, the TP25 probe was described in detail. Then, to solve the major weaknesses of the tool, a set of proposals were presented and submitted to a comparative study, to obtain the most adequate adaptation solution for the project requirements. Thus, a first prototype was created, which was improved to optimize its installation process in the engine. Then, a final prototype was obtained, which starting from the original configuration of the TP25 probe, integrates current and easy handling technology, supported by a structure which attests the robustness of the whole set. The improvements introduced by the suggested modification, allow to achieve the outlined goals, since the pressure and temperature probe with a new integrated interface, now more robust, reliable and functional, could return to its task in the test bench, contributing to the performance monitoring of the CFM56-3 engine. After completing the first stage of the work, in which a definitive solution was obtained for the repair of the TP25 probe, a CFD simulation was performed in the Inter-Compressor Duct of the CFM56-3 engine, which enabled the prediction of the fluid flow conditions considering, or not, the presence of the afore mentioned probe. By applying the developed software tool, we wanted to determine the influence of the aerodynamic shape of the probe on the pressure and temperature measurements, and to assess the need to make changes in the configuration of the probe as a condition for the optimization of its performance. Initially, the on-site dimensioning of the surrounding structure of the Inter-Compressor Duct was carried out, whose technical information is kept confidential by the manufacturer. With the CATIA V5 software, the geometry of the various components was obtained, with relevance to the present study - Fan Frame, VBV, Scoop and TP25 Probe, which enabled the definition of the fluid region with the probe installed (ICD Air Volume) and under undisturbed flow conditions (ICDAV Without Sensor). The numerical mesh applied to each domain was developed using the HELYX-OS, and the ANSYS Fluent 16.2 software was used to carry out the numerical study. Two viscous models were applied, the Standard K-e and the Realizable K-e. For the boundary conditions, the Booster discharge (domain entry) was defined as Mass Flow Inlet, the HPC inlet (domain exit) was defined as Pressure Outlet, and the other surfaces, including the sensing elements of the probe (ICD Air Volume), as Wall boundary. After the simulations were completed and the model validated, the distributions for the main thermodynamic parameters along the considered domains were presented. The results confirm the interference of the TP25 probe body on the flow characteristics, so its influence was quantified by means of the pressure and temperature measurement error, which remained below 5% and 1.5%, respectively. It can, therefore, be concluded that the measurements obtained from the Inter-Compressor Duct, not being immune to error, ensure adequate monitoring of the main thermodynamic parameters of the engine. Thus, the optimization of the aerodynamic shape of the TP25 probe is not justified, since the improvements will hardly justify the costs associated with the development of a new prototype.
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Morão, Inês Isabel Ascenção Costa. "The influence of jet fuels on the emission of pollutants." Master's thesis, 2019. http://hdl.handle.net/10400.6/8947.
Full textAbstract:
In the present work a CFD simulation was performed, the study component was a CFM56-3 combustor. It was intended to simulate the combustion and emission of pollutants from the different jet fuels (Jet A, Jet B and TS-1), when burning these through ICAO's LTO cycle.
Being this a continuity study, the CAD made by Jonas Oliveira was used. The mesh was constructed with HELYX-OS software and the numerical study was made using the commercial software ANSYS Fluent 16.2.
Large Eddy Simulation (LES) was used as viscous model. This model is a more efficient than other models to better understand the processes of pollutant formation and to provide their quantitative prediction. The atomization was considered in this study.
It can be concluded, amongst all the fuels simulated that increasing the power produces higher NOx. There was also an erratic behaviour in the emissions of UHC and CO results, because an empiric model was used and not a detailed chemical model. [...]No presente trabalho foi realizada uma simulação de CFD, sendo o componente de estudo uma câmara de combustão do motor CFM56-3. Simulou-se a combustão e analisou-se as emissões de poluentes de diferentes combustíveis (Jet A, Jet B e TS-1). Sendo este um estudo de continuidade, foi usado o CAD elaborado por Jonas Oliveira. Para a elaboração da malha o usado o software HELYX-OS e para o cálculo numérico foi utilizado o ANSYS Fluent 16.2. O modelo viscoso usado foi Large Eddy Simulation (LES). Este modelo é mais eficiente que os outros modelos para perceber o processo de formação dos poluentes. A atomização foi considerada neste estudo. Conclui-se que, entre todos os combustíveis simulados, com o aumento da potência as emissões de NOx aumentaram também. Verificou-se um comportamento errático nas emissões de UHC e CO, devido ao facto de se ter utilizado um modelo empírico e não um modelo químico detalhado. [...]
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Leal, Miguel António Viegas. "Eficácia do controlo de sopro por jatos retangulares num difusor de admissão ultracompacto." Master's thesis, 2018. http://hdl.handle.net/10400.6/8561.
Full textAbstract:
A presente investigação teve como propósito o estudo, recorrendo a análises numéricas, das características
do escoamento num difusor de admissão em serpentina com elevada taxa de difusão
e do aumento do rendimento do mesmo pelo uso de jatos em orifícios retangulares, a fim de que
esta técnica de controlo possa ser considerada como uma solução ao problema do escoamento
neste género de difusores. Para tal, dimensionou-se concetualmente um difusor ultracompacto,
em serpentina, tendo em vista a baixa observabilidade de radar e de infravermelhos, com 0,45
metros de deslocamento vertical da linha central, 1,3 metros de comprimento, e uma razão de
abertura de 2,0. Empregou-se uma técnica de controlo do escoamento que consistiu na injeção
de ar através de pequenos oríficios retangulares, e perpendicularmente, com um caudal de
mássico global limitado a 1% daquele à entrada do ducto. Diversas orientações dos orifícios em
relação ao sentido do escoamento - 0º, 15º, 30º e 45º - foram examinadas de modo a perceber
a sua influência na eficácia desta técnica de controlo. Os jatos foram instalados a montante
dos pontos de separação do escoamento que ocorrem em ambas as paredes, superior e inferior.
As respetivas geometrias foram desenhadas no software CATIA V5R21, e exportadas em ficheiro
STL para o código gerador de malhas. As malhas, híbridas e predominantemente hexaédricas,
geraram-se com o código aberto SnappyHexMesh, através da interface gráfica aberta HELYX-OS.
A resolução numérica teve por base a utilização do modelo de turbulência k - " realizável,
com funções de parede. Adotou-se o software comercial ANSYS FLUENT 16.2 para o cálculo das
equações de governo discretizadas. Para as condições testadas, o escoamento apresentou duas
regiões de separação, após a primeira curva na parede inferior, e outra, de maior intensidade,
ao início da segunda curva na parede superior, ambas dotadas de escoamentos secundários.
Qualitativamente, os resultados sem controlo estão de acordo com estudos semelhantes encontrados
na literatura. A técnica de controlo utilizada, quando aplicada na parede inferior,
permitiu, para uma orientação de 0º, eliminar completamente a separação do escoamento e os
escoamentos secundários nesta região. Para as orientações de 15º, 30º e 45º os jatos revelaramse
ineficazes, no entanto introduziram melhorias inesperadas na parede superior. No que diz
respeito à última, nenhuma das configurações aí testadas conseguiu mitigar a separação e os
escoamentos secundários, revelando até, à exceção da orientação de 0º, um efeito contrário ao
esperado através de uma maior deterioração do escoamento. No geral, conclui-se que a viabilidade
dos jatos retangulares para controlo do escoamento é limitada, à exceção da configuração
alinhada com o escoamento, que permite redistribuir com sucesso a pressão total nas regiões
de parede onde o escoamento se encontra separado e os gradientes adversos de pressão não são
tão intensos como os sentidos na parede superior.Numerical simulations were carried out in order to investigate the flow characteristics in an intake serpentine diffuser with a high diffusion rate and the increase of its efficiency through the use of rectangular orifice vortex generator jets, so this technique can be considered as a solution for the aerodynamic problems that this type of ducts usually present. That way, a conceptual design of an ultracompact, serpentine, low observable diffuser was performed, with a vertical offset of 0,45 meters, length of 1,3 meters, and an area ratio of 2,0. A jet flow control technique through rectangular orifices was applied, with air blowing perpendicularly with a global mass flow rate limited to 1% of value at the duct inlet. Several orientations of the orifices with respect to the mainflow - 0º, 15º, 30º and 45º - were tested. The jets were installed upstream of the separation points found at both top and bottom walls. The CAD models were designed with the CATIA V5R21 software, and exported through a STL file to the mesh generator code. The numerical meshes were hex-dominant and were generated in the open-source code SnappyHexMesh, through the graphical user interface HELYX-OS. The k-" realizable turbulence model, with wall functions, was adopted to compute the numerical solution. The commercial software ANSYS FLUENT 16.2 was used to compute the discretized governing equations. For the conditions tested, the mainflow presented two separation regions, one after the first bend in the bottom wall, and a more intense one after the second bend in the top wall. Both separation regions were characterized by secondary flows. Qualitatively, the results without control agree with similar studies found in literature. The control technique when applied to the bottom wall, for an orientation of 0º, eliminated completely the separation region and the secondary flows in this location. For the 15º, 30º and 45º orientations, despite the jets were ineffective, there was an unexpectedly improvement at the top wall of the second bend. Concerning to the last one, none of the configurations tested there were capable of mitigating the separation and the secondary flows; excluding the 0º case, all the other orientations actually deteriorated the flow. Overall, one can conclude that the viability of rectangular vortex generator jets for flow control is limited, excepting the configuration aligned with the mainflow, which succeeds at redistributing the total pressure at near wall flow where separations occurs and the adverse pressure gradients are not as intense as found in the top wall.