Дисертації з теми "Aerospace engineering – Simulation methods"
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Boles, John Arthur. "Hybrid Large-Eddy Simulation/Reynolds-Averaged Navier-Stokes Methods and Predictions for Various High-Speed Flows." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-08122009-170842/.
Повний текст джерелаButler, William M. "The Impact of Simulation-Based Learning in Aircraft Design on Aerospace Student Preparedness for Engineering Practice: A Mixed Methods Approach." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/27601.
Повний текст джерелаPh. D.
Adams, Ryan, and s200866s@student rmit edu au. "Evaluation of computerised methods of design optimisation and its application to engineering practice." RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2006. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20070130.122013.
Повний текст джерелаTaha, Wael. "Simulation of unsteady 3-D viscous compressible propeller flow by finite element method." Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80145.
Повний текст джерелаSenneberg, Sofia. "Methods for validating a flight mechanical simulation model for dynamic maneuvering." Thesis, KTH, Flygdynamik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299412.
Повний текст джерелаFlygmekaniska simulatorer är av stor betydelse under utvecklingen av ett nytt stridsflygplan. Möjligheten att simulera och utvärdera under tidens gång har stor betydelse både ur tid- och kostnadsbesparings perspektiv men även ur flygsäkerhetsperspektiv när det är dags för första flygning. Syftet med det här projektet är att utveckla en metod för jämförelse mellan simulering och flygprov för att validera hur bra den flygmekaniska simulatorn kan förutspå flygplansbeteende. En viktig del i projektet syftar till hur skillnader i resultaten kan hittas och analyseras, till exempel skillnader mellan olika flygplansindivider eller lastkonfigurationer. Arbetet presenterat här har resulterat i en modell som är bra för jämförelse av en stor mängd data där det är enkelt att spåra var skillnaderna har uppstått.
Papp, John Laszlo. "SIMULATION OF TURBULENT SUPERSONIC SEPARATED BASE FLOWS USING ENHANCED TURBULENCE MODELING TECHNIQUES WITH APPLICATION TO AN X-33 AEROSPIKE ROCKET NOZZLE SYSTEM." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin962118912.
Повний текст джерелаSuksila, Thada. "The cathode plasma simulation." Thesis, University of Southern California, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3704256.
Повний текст джерелаSince its invention at the University of Stuttgart, Germany in the mid-1960, scientists have been trying to understand and explain the mechanism of the plasma interaction inside the magnetoplasmadynamics (MPD) thruster. Because this thruster creates a larger level of efficiency than combustion thrusters, this MPD thruster is the primary cadidate thruster for a long duration (planetary) spacecraft. However, the complexity of this thruster make it difficult to fully understand the plasma interaction in an MPD thruster while operating the device. That is, there is a great deal of physics involved: the fluid dynamics, the electromagnetics, the plasma dynamics, and the thermodynamics. All of these physics must be included when an MPD thruster operates.
In recent years, a computer simulation helped scientists to simulate the experiments by programing the physics theories and comparing the simulation results with the experimental data. Many MPD thruster simulations have been conducted: E. Niewood et al.[5], C. K. J. Hulston et al.[6], K. D. Goodfellow[3], J Rossignol et al.[7]. All of these MPD computer simulations helped the scientists to see how quickly the system responds to the new design parameters.
For this work, a 1D MPD thruster simulation was developed to find the voltage drop between the cathode and the plasma regions. Also, the properties such as thermal conductivity, electrical conductivity and heat capacity are temperature and pressure dependent. These two conductivity and heat capacity are usually definded as constant values in many other models. However, this 1D and 2D cylindrical symmetry MPD thruster simulations include both temperature and pressure effects to the electrical, thermal conductivities and heat capacity values interpolated from W. F. Ahtye [4]. Eventhough, the pressure effect is also significant; however, in this study the pressure at 66 Pa was set as a baseline.
The 1D MPD thruster simulation includes the sheath region, which is the interface between the plasma and the cathode regions. This sheath model [3] has been fully combined in the 1D simulation. That is, the sheath model calculates the heat flux and the sheath voltage by giving the temperature and the current density. This sheath model must be included in the simulation, as the sheath region is treated differently from the main plasma region.
For our 2D cylindrical symmetry simulation, the dimensions of the cathode, the anode, the total current, the pressure, the type of gases, the work function can be changed in the input process as needed for particular interested. Also, the sheath model is still included and fully integrated in this 2D cylindrical symmetry simulation at the cathode surface grids. In addition, the focus of the 2D cylindrical symmetry simulation is to connect the properties on the plasma and the cathode regions on the cathode surface until the MPD thruster reach steady state and estimate the plasma arc attachement edge, electroarc edge, on the cathode surface. Finally, we can understand more about the behavior of an MPD thruster under many different conditions of 2D cylindrical symmetry MPD thruster simulations.
Kalaver, Satchidanand Anil. "Management of reference frames in simulation and its application to error reduction in numerical integration." Thesis, Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/12406.
Повний текст джерелаLi, Yuwen. "Dynamics modeling and simulation of flexible airships." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=18756.
Повний текст джерелаL'intérêt renouvelé envers les dirigeables a créé un besoin de modèles dynamique et de simulations de ces véhicules plus légers que l'air. Cette thèse traite d'un cadre théorique qui intègre la dynamique de vol, la dynamique structurale, l'aérostatique et l'aérodynamique des dirigeables flexibles. La recherche débute par une étude d'un modèle dynamique fondé sur l'hypothèse d'un corps rigide. Une approche de calcul d'aérodynamique complète est présentée, où les forces et les moments aérodynamiques sont classés par catégories basées sur différents effets physiques. Une série d'approches de prédiction des différents effets aérodynamiques est unifiée et appliqué aux dirigeables. Les résultats numériques des dérivés aérodynamiques et des réponses simulées à des commandes spécifiés sont comparés à des résultats d'essais provenant d'autre œuvres. Une fois l'aérodynamique et le modèle de corps rigide validés, les équations de mouvement d'un dirigeable élastique sont dérivées avec une formulation Lagrangienne. Le dirigeable est modélisé comme poutre Euler-Bernoulli et les déformations sont représentées par des fonctions de forme choisies. Afin de prendre en considération la dépendance entre les forces aérodynamiques et l'élasticité structurale, la vitesse locale sur le véhicule déformé est employée dans le calcul des forces aérodynamiques. En conclusion, avec les forces d'inertie, de gravité, d'aérodynamique et de commande incorporées, le modèle dynamique d'un dirigeable flexible est exprimé sous la forme d'un ensemble d'équations différentielles ordinaires non-linéaires. Le modèle proposé est mis en pratique sous forme de simulation dynamique afin d'analyser les caractéristiques dynamiques du dirigeable Skyship-500. Des résultats de simulation sont présentés pour démontrer l'influence de la déformation structurale sur les forces aérodynamiques et le comportement dynamique du di
Buettner, Robert W. "Dynamic Modeling and Simulation of a Variable Cycle Turbofan Engine with Controls." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1496179248257409.
Повний текст джерелаGehly, Steve. "Estimation of geosynchronous space objects using finite set statistics filtering methods." Thesis, University of Colorado at Boulder, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10195335.
Повний текст джерелаThe use of near Earth space has increased dramatically in the past few decades, and operational satellites are an integral part of modern society. The increased presence in space has led to an increase in the amount of orbital debris, which poses a growing threat to current and future space missions. Characterization of the debris environment is crucial to our continued use of high value orbit regimes such as the geosynchronous (GEO) belt. Objects in GEO pose unique challenges, by virtue of being densely spaced and tracked by a limited number of sensors in short observation windows. This research examines the use of a new class of multitarget filters to approach the problem of orbit determination for the large number of objects present. The filters make use of a recently developed mathematical toolbox derived from point process theory known as Finite Set Statistics (FISST). Details of implementing FISST-derived filters are discussed, and a qualitative and quantitative comparison between FISST and traditional multitarget estimators demonstrates the suitability of the new methods for space object estimation. Specific challenges in the areas of sensor allocation and initial orbit determination are addressed in the framework. The sensor allocation scheme makes use of information gain functionals as formulated for FISST to efficiently collect measurements on the full multitarget system. Results from a simulated network of three ground stations tracking a large catalog of geosynchronous objects demonstrate improved performance as compared to simpler, non-information theoretic tasking schemes. Further studies incorporate an initial orbit determination technique to initiate new tracks in the multitarget filter. Together with a sensor allocation scheme designed to search for new targets and maintain knowledge of the existing catalog, the method comprises a solution to the search-detect-track problem. Simulation results for a single sensor case show that the problem can be solved for multiple objects with no a priori information, even in the presence of missed detections and false measurements. Collectively, this research seeks to advance the capabilities of FISST-derived filters for use in the estimation of geosynchronous space objects; additional directions for future research are presented in the conclusion.
Launglucknavalai, Kevin. "Simulation of Liquid Droplet in Air and on a Solid Surface." Thesis, University of California, Irvine, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1537051.
Повний текст джерелаAlthough multiphase gas and liquid phenomena occurs widely in engineering problems, many aspects of multiphase interaction like within droplet dynamics are still not quantified. This study aims to qualify the Lattice Boltzmann (LBM) Interparticle Potential multiphase computational method in order to build a foundation for future multiphase research. This study consists of two overall sections.
The first section in Chapter 2 focuses on understanding the LBM method and Interparticle Potential model. It outlines the LBM method and how it relates to macroscopic fluid dynamics. The standard form of LBM is obtained. The perturbation solution obtaining the Navier-Stokes equations from the LBM equation is presented. Finally, the Interparticle Potential model is incorporated into the numerical LBM method.
The second section in Chapter 3 presents the verification and validation cases to confirm the behavior of the single-phase and multiphase LBM models. Experimental and analytical results are used briefly to compare with numerical results when possible using Poiseuille channel flow and flow over a cylinder. While presenting the numerical results, practical considerations like converting LBM scale variables to physical scale variables are considered. Multiphase results are verified using Laplaces law and artificial behaviors of the model are explored.
In this study, a better understanding of the LBM method and Interparticle Potential model is gained. This allows the numerical method to be used for comparison with experimental results in the future and provides a better understanding of multiphase physics overall.
Germann, Kenneth Paul. "T-6A TEXAN II IN-FLIGHT SIMULATION AND VARIABLE STABILITY SYSTEM DESIGN." MSSTATE, 2009. http://sun.library.msstate.edu/ETD-db/theses/available/etd-12162009-091123/.
Повний текст джерелаShimmin, Kyle. "An Architecture for Rapid Modeling and Simulation of an Air-Vehicle System." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1469453436.
Повний текст джерелаBhutoria, Vaibhav. "Direct numerical simulation of compressible homogeneous turbulence using natural initial conditions." Thesis, Purdue University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1544113.
Повний текст джерелаReynolds averaged Navier Stokes (RANS) solvers have become the workhorse for simulating turbulent flows for most practical purposes. While the incompressible turbulence models used with RANS equations have improved considerably in their predictive capability, significant breakthrough has not been achieved for their compressible counterparts. With the advancement in computing power, high resolution direct numerical simulation (DNS) of low Reynolds number turbulent flows has become feasible. DNS of simple turbulent flows provides a detailed database which can be used for developing and testing turbulence models. In this work, we perform DNS of compressible homogeneous turbulence—decaying isotropic turbulence and homogeneous shear flow—for a range of initial turbulent Mach numbers, (Mt 0 = 0.05–0.4) using the more natural initial conditions. Simulations were performed on grids with 1283 and 2563 points. Compressibility effects on the evolution of turbulent kinetic energy were studied. We found negligible compressibility effects for decaying isotropic turbulence, while homogeneous shear flow demonstrated compressibility effects in the growth rate of turbulent kinetic energy. Compressibility corrections to turbulence models in the form of the ratio &epsis;d/&epsis; s, have been tested with the results from the simulations. For decaying isotropic turbulence a [special characters omitted] scaling was found to be better than [special characters omitted] while for homogeneous shear flow it was the opposite. The small value of the ratio &epsis;d/&epsis;s in decaying isotropic turbulence makes the [special characters omitted] scaling less relevant. Based on the DNS results of homogeneous shear flow, a new correction parameterized by the gradient Mach number, Mg, is proposed. The parameter Cμ, which is assumed constant for incompressible two equation eddy viscosity models, is computed explicitly from the DNS data. An Mg, dependence of the parameter, Cμ, is proposed.
Bhandari, Subodh. "Development of Six-Degree-of-Freedom Piecewise Simulation of Aircraft Motion in SIMULINK." MSSTATE, 2004. http://sun.library.msstate.edu/ETD-db/theses/available/etd-07092004-014851/.
Повний текст джерелаNajafi-Yazdi, Alireza. "Large eddy simulation of sound generation by turbulent reacting and nonreacting shear flows." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107761.
Повний текст джерелаL'objectif de cette étude est d'obtenir la meilleure compréhension des mécanismesde géneration de bruit par des jet subsoniques. Cette étude est basée sur simulations aux grandes échelles de jets réactifs et sans réactifs. Des calculs numériques employant des schéme compacts de sixiéme ordre. L'integration temporelle fut éxéciteé à l'aide de schéme Runge-Kutta de de quatrième ordre. Des schéme à faible dispersion et dissipation numérique. Un formulation intégrale basée sur les analogies acoustiques fut développées pour la prédiction du champ acoustique lointain pour les sources et observateure en mouvement dans un fluide avec vitesse uniforme. La formulation fut implémentée à l'aide d'algorithmes facilitant l'implémentation pour le traitement de données d'écoulement en haute performance utilisant des outils de simiulation à grande échelle. Les champs sonore produit par un jet turbulent non-réactif avec nombre de Mach de 0.9, et un nombre de Reynolds ReD = 400, 000 fut étudié. L'effect de la taille du maillage sur la précision de l'écoulement en champs proche et e champs sonore loin de source fut analysé. La sous-résolution de la couche de cisaillement à la sortie du jet méne à l'apparition de structures cohérentes et forte radiation qui ne sort pas physiquement réalistes. Deux mécanismes principaux de génération sonore par jets subsoniques furent identifiés. Le premier mécanisme est l'étirement et la distorsion de structures tourbillonnaires cohérentes, en particulier prés de la fin du coere potentiel. Ce mécanisme est quadripolaire, et émet principalement vers l'arriére du jet dans la direction de l'écoulement. Le seconde mécanisme semble être constitué de vibration transversale de la couche de cisaillement en réponse à la présemce de structures cohérentes dans la jet. Semblable à la radiation d'une plaque à bonds finis, la contribution de ce méchanisme est dipolaire et domine la champs sonore dans la direction transversale, perpendiculaire au jet. L'utilisation de plusieurs microjet fut investiguée pour la réduction du bruit. L'injection à l'aide de microjets précipite la transition à la turbulence, favorisent le mélange et la destrcutction de structures cohérentes de grande échelle. Un filtrage en bandes de étroites fut effectué. Ce traitement des données numériquepermet de visualiser les relations complexes entre l'écoulement et les onds sonores émises. Les résultats démontrent l'importance de modes circumférenciele, ce qui a des conséquenecs pour les modiles dits de paquets d'onde pour la preédiction du bruit du jet. Des simulation numériques d'écoulement et champs sonore d'une flame sans prémélange furent aussi éxécutées. Les simulations incluent encore une fois l'écoulement et le champ sonore associé, obtenus directement des équations de Navier Stokes compressibles. Un modèle flammelette épaissie fut proposé que donne flammes épaissies artificiellement qui peuvent être mieux résolus sur le maillage. Le bruit de combustion a des caractéristiques monopolaires aux basses fréquences. Principales sources de bruit semblent être situé dans la couche de cisaillement.
Robertson, Eric D. "Verification, validation, and implementation of numerical methods and models for OpenFOAM 2.0 for incompressible flow." Thesis, Mississippi State University, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1596091.
Повний текст джерелаA comprehensive survey of available numerical methods and models was performed on the open source computational fluid dynamics solver OpenFOAM version 2.0 for incompressible turbulent bluff body flows. Numerical methods are illuminated using source code for side-by-side comparison. For validation, the accuracy of flow predictions over a sphere in the subcritical regime and delta wing with sharp leading edge is assessed. Solutions show mostly good agreement with experimental data and data obtained from commercial software. A demonstration of the numerical implementation of a dynamic hybrid RANS/LES framework is also presented, including results from test studies.
Stanescu, Dan. "Comparison of several numerical methods for solving the Euler equations for compressible aerodynamic flows." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22679.
Повний текст джерелаSingh, Sonu Shravan Kumar. "Buckling and Wrinkling Analysis of Composite Sandwich Plates Using Finite Element Methods." Thesis, California State University, Long Beach, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10752150.
Повний текст джерелаComposite sandwich plates are widely used in aerospace, automobile and shipbuilding industries. Composite sandwich plates have many different types of failure modes. A comparative study of composite sandwich plates with different finite element modeling approaches for predicting buckling and wrinkling failure response is described in this thesis. The research considers composite sandwich plates with isotropic and anisotropic face-sheets with a thick core. Finite element solutions are obtained using Abaqus/CAE 2016 software by conventional shell element models and conventional shell/solid element models. This study investigates results obtained using finite element methods and compares them to experimental and analytical solutions for overall buckling and face-sheet wrinkling. Results of the study indicate that finite element methods provide an accurate and effective modeling approach for predicting both overall buckling and wrinkling response.
Furthermore, the study also explored buckling response of composite sandwich panels with different core thickness and face-sheet fiber angle orientation. The study found that the shell/solid element model provides an appropriate and effective modeling method to predict both overall buckling and local wrinkling behavior in composite sandwich plates.
Nesti, Leonardo. "Numerical Simulations of Supersonic Flows in an Aerospike using OpenFOAM." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Знайти повний текст джерелаMcDaniel, Keith Scott. "Three Dimensional Simulation of Time-Dependent Scramjet Isolator /Combustor Flowfields Implemented on Parallel Architectures." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20001228-204538.
Повний текст джерелаMcDaniel, Keith S. Three Dimensional Simulation of Time-DependentScramjet Isolator / Combustor Flowfields Implemented onParallel Architectures, ( Under the directions of Dr. J. R. Edwards). The development of a parallel Navier-Stokes solver for computing time-dependent,three-dimensional reacting flowfields within scramjet (supersonic combusting ramjet)engines is presented in this work. The algorithm combines low-diffusion upwinding methods, timeaccurate implicit integration techniques, and domain decomposition strategies to yield an effectiveapproach for large-scale simulations. The algorithm is mapped to a distributed memoryIBM SP-2 architecture and a shared memory Compaq ES-40 architecture using the MPI-1 message-passingstandard. Two and three-dimensional simulations of time-dependent hydrogen fuel injection into a modelscramjet isolator / combustor configuration at two equivalence ratios are performed. Thesesimulations are used to gain knowledge of engine operability, inlet performance, isolatorperformance, fuel air mixing, flame holding, mode transition, and engine unstart.Results for an injection at a ratio of 0.29 show qualitative agreement withexperiment for the two-dimensional case, but revealed a slow progression towardengine unstart for the three-dimensional case. Injection at an equivalence ratio of 0.61resulted in engine unstart for both two-dimensional and three-dimensional cases.Engine unstart for the three-dimensional case occurs as a response to the formation and growthof large pockets of reversed flow along the combustor side wall. These structuresdevelop at an incipient pressure above 154 kPa and result in significant blockage of the core flow,additional compression, and chemical reaction within the boundary layer. All of these factors promotea much more rapid unstart as compared with the two-dimensional case.
Bachman, Cary Robert. "A new methodology for the numerical simulation of wall bounded turbulent flows." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/289723.
Повний текст джерелаHerman, Jonathan F. C. "Improved Collocation Methods to Optimize Low-Thrust, Low-Energy Transfers in the Earth-Moon System." Thesis, University of Colorado at Boulder, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3743638.
Повний текст джерелаModern and near-future Solar Electric Propulsion capabilities enable many new missions that were inconceivable using chemical propulsion systems. Many of these involve highly complex trajectories that are very challenging to design. New tools are needed that effectively utilize the rapidly growing parallel processing capabilities of modern computers. This research improves Gauss-Lobatto collocation methods, which are known to perform very well for low-thrust trajectory optimization, by formulating them as massively parallel processes. The parallelized elements of the problem formulation execute up to 11 times faster, depending on what force model is used and when evaluated by themselves. When accounting for the operations of the nonlinear programming solver, this translates to up to 3.7 times faster performance for solving a complete trajectory optimization problem, again depending on the force model that is used. The remaining barriers to further performance improvements, and the conditions upon which these depend, are clearly identified.
The implemented methods are combined into an optimization tool named Maverick. More general improvements to the formulation of the Gauss-Lobatto collocation methods are also developed and included in Maverick, which permit a more flexible use of these optimization schemes and enable them to find more complex solutions. One example of this is Maverick's ability to autonomously introduce gravity assists into trajectories, which greatly increases the utility and convergence radius of these methods.
In order to demonstrate the benefit of this work, three applications are studied. The first are transfers between halo-like orbits in the Earth-Moon system, which shows this is likely an unattractive region for missions like the New Worlds Observer. The second application investigates stabilization maneuvers in lunar distant retrograde orbits. This work demonstrates the feasibility of these stabilization transfers for a variety of sample return missions, such as the upcoming Asteroid Redirect Mission. The final application discussed is a series of multi-body low-thrust transfers from the Earth to the Moon that efficiently utilize highly variable dynamics to reduce propellant consumption, which is relevant for a variety of future mission concepts. These are computed for a wide range of flight times, showing that reductions up to 45% of the transfer time can be achieved with a propellant consumption as little as 0.5% of the total spacecraft mass. Up to 90% of the flight time can be eliminated for a propellant cost of 4% of the total spacecraft mass, or up to 83% for a propellant cost of less than 2%. The developed algorithm seamlessly transitions its solutions from full low-thrust, low-energy trajectories to the 'pure' low-thrust trajectories that define the shortest transfer trajectories, validating its robust performance. Beyond these quantifiable results, these examples illustrate the complexity of the solutions that can be identified with these improved implementations of Gauss-Lobatto collocation methods, with many instances where the optimization method autonomously introduces powered gravity assists, an unusual capability that has the potential for useful application to many other trajectory optimization problems.
Norman, Patrick J. "Methods for the efficient and accurate simulation of marine and aerospace electrical power networks." Thesis, University of Strathclyde, 2009. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=11457.
Повний текст джерелаPerez, Hugo. "New Measurement Methods For Ground Vibration Test." Thesis, KTH, Flygdynamik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-276465.
Повний текст джерелаFlygtestning är ett viktigt steg av att utveckla ett flygplan. Genom en uppsättning tester blir varje ny eller modifierad flygkonfiguration certifierad. Certifiering garanterar säkerhet, kvalitet och pålitlighet. Avdelningen för flygtestning på Dassault Aviation är ansvarig för genomförandet av flygtester I Istres, södra Frankrike. Ett viktigt test före flygning är Ground Vibration Test (GVT). Målet med detta test är att mäta strukturens egenfrekvenser och lägesformer. Resultaten jämförs sedan med dem som ges av den finita elementmodellen för att kunna verifiera eller uppdatera dem. Att fastställa det strukturella beteendet är av stor vikt för flygplanets säkerhet; till exempel hjälper det att stipulera planets flygstabilitet och fladdergränsen. Under ostadiga aerodynamiska belastningar kan flygplanets struktur vara dynamiskt instabil, vilket innebär att svängningens amplitude ökar med med tiden. Resonansfenomenet som kallas för fladder kan allvarligt skada eller till och med leda till total förstörelse av flygplanets struktur. GVT: er utförs genom att utsätta flygplanet för svängande krafter på utsedda delar av planet. Sedan används hundratals accelerometrar för att mäta deformationerna. Genom att veta exakt inmatningsexitering och hur strukturen svarar, är det möjligt att beräkna förhållandena (de så kallade överföringsfunktioner) mellan de applicerade oscillerande krafterna och accelerationsåtgärderna. Denna mätmetod baserad på accelerometrar är mycket exakt; installationen tar emellertid mycket tid och skapar en viktig överbelastning på grund av ett stort antal accelerometrar och kablar som används. Som en del av markvibrationstest presenterar detta dokument en utredning om nya innovativa mätmetoder som kan förbättra, komplettera eller till och med ersätta de nuvarande metoderna baserade på accelerometrar. Denna rapport är strukturerad i tre delar; en kort konstnärligt samling där det presenteras några innovativa mätmetoder och sedan två delar med fokus på experiment av två mätmetoder med hjälp av rapids kameror och 3D-laser. Arbetet är ett första steg i en lång forskning som säkert på några år kommer att avföra accelerometrar och ersätta dem med nya metoder som är mycket bekvämare.
Kummer, Joseph. "Simulation of the cross-flow fan and application to a propulsive airfoil concept." Related electronic resource: Current Research at SU : database of SU dissertations, recent titles available full text, 2006. http://proquest.umi.com/login?COPT=REJTPTU0NWQmSU5UPTAmVkVSPTI=&clientId=3739.
Повний текст джерелаRangel, Enger Eric. "Spacecraft attitude determination methods in an educational context." Thesis, KTH, Rymdteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-265612.
Повний текст джерелаDetta arbete har som mål att strukturera innehållet i en kurs om Attitydbestämningsmetoder inom flyg- och rymdteknikmastersprogram. Ett urval av böcker, artiklar, avhandlingar, webbsidor och filmer granskades för att identifiera de mest relevanta ämnena inom statisk och dynamisk attitydbestämning och de olika sätten att presentera dem i ett utbildningssammanhang. Teorin presenteras på ett förenklat sätt och några exemplar visas för att illustrera den teoretiska delen. Avslutningsvis, diskuteras de huvudsakliga lärandemålen, nödvändig handledning och övningstid, samt betygsättning.
Rodriguez, Daniel. "Numerical Simulation of a Flowfield Around a Hypersonic Missile with Lateral Jets." Thesis, Florida Atlantic University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10605920.
Повний текст джерелаThis work uses computational fluid dynamics to study the flowfield around a hypersonic missile with two lateral jets to provide control in place of control surfaces. The jets exhaust an H2-O2 mixture at Mach number of 2.9 with a jet pressure ratio of roughly 10,500. The jets are staggered axially and circumferentially in such a way to produce pitch and yaw. The flowfield of such a jet configuration is characterized at several angles of attack and the corresponding force coefficients and amplification factors are provided. The freestream air and H2-O2 plume is treated as inert for the majority of the calculations. Special cases are treated with finite rate chemical kinetics and compared to the inert flowfield to ascertain the effects that chemical reactions have on the force coefficients. It was found that the flowfield was only slightly altered from the familiar one jet flowfield when the second jet is active. The flow topology and vortex structures tend to shift towards the second jet but the overall structure remains the same. The normal force amplification factors are close to unity over the range of angle of attack due to the thrust being so high with the two jet configuration having a lower amplification factor compared to firing a single jet. Treating the flowfield as chemically reacting did not affect the force values much: the difference being 0.3% for an angle of attack of 0°.
Śmiałek, Adam. "Simulation and control toolkit for small satellite projects." Thesis, Luleå tekniska universitet, Rymdteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-80721.
Повний текст джерелаPerry, Mark Joseph. "Analysis of resin transfer molding: Material characterization, molding and simulation /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1382637062.
Повний текст джерелаMalechuk, Andrew Martin. "Simulation of Transitional Flow over an Elliptic Cone at Mach 8 using a One-Equation Transition/Turbulence Model." NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-11192002-194918/.
Повний текст джерелаStill, Vincent. "Thermal Control Design and Simulation of a Space Mission." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-71784.
Повний текст джерелаSebastian, Thomas Jr. "Methods for the Determination of Aerodynamic Parameters and Trajectory Reconstruction of the Orion Command Module from Scale Model Aeroballistic Flight Data." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-11042008-170009/.
Повний текст джерелаShi, Jianming Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "Identification and investigation of local optima in aerospace structural design." Awarded by:University of New South Wales. School of Mechanical and Manufacturing Engineering, 2006. http://handle.unsw.edu.au/1959.4/31106.
Повний текст джерелаChambers, Nicholas Roy. "DESIGN AND NUMERICAL SIMULATION OF A LINEAR SHAPED CHARGE SEPARATION MECHANISM FOR FIRST STAGE SEPARATION OF THE ARES I LAUNCH VEHICLE." MSSTATE, 2009. http://sun.library.msstate.edu/ETD-db/theses/available/etd-04032009-084554/.
Повний текст джерелаBarritt, Brian James. "The Modeling, Simulation, and Operational Control of Aerospace Communication Networks." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1499348546519051.
Повний текст джерелаYu, Huan. "New Statistical Methods for Simulation Output Analysis." Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/4931.
Повний текст джерелаFiore, Andrew M. (Andrew Michael). "Fast simulation methods for soft matter hydrodynamics." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122848.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references.
This thesis describes the systematic development of methods to perform large scale dynamic simulations of hydrodynamically interacting colloidal particles undergoing Brownian motion. Approximations to the hydrodynamic interactions between particles are built from the periodic fundamental solution for flow at zero Reynolds number and are methodically improved by introducing the multipole expansion and constraints on particle dynamics. Ewald sum splitting, which decomposes the sum of slowly decaying interactions into two rapidly decaying sums evaluated indepently in real space and Fourier space, is used to accelerate the calculation and serves as the basis for a new technique to sample the Brownian displacements that is orders of magnitude faster than prior approaches. The simulation method is first developed using the ubiquitous Rotne-Prager approximation for the hydrodynamic interactions.
Extension of the Rotne-Prager approximation is achieved via the multipole expansion, which introduces the notion of induced force moments whose value is determined from the solution of constraint problems (for example, rigid particles cannot deform in flow), and methods for handling these multipole-based constraints are illustrated. The multipole expansion converges slowly when particles are nearly touching, a problem which is functionally solved for dynamic simulations by including divergent lubrication interactions, in the style of Stokesian Dynamics. The lubrication interactions effectively introduce an additional constraint on the relative motion of closely separated particle pairs. This constraint is combined with the multipole constraints by developing a general method to handle nearly arbitrary dynamic constraints using saddle point matrices. Finally, the methods developed herein are applied to study sedimentation in suspensions of attractive colloidal particles.
The simulation results are used to develop a predictive model for the hindered/promoted settling function that describes the mean sedimentation rate as a function of particle concentration and attraction strength.
"The research in this thesis was supported by the MIT Energy Initiative Shell Seed Fund and NSF Career Award CBET-1 554398"
by Andrew M. Fiore.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemical Engineering
Tian, Ming. "Numerical Simulation of the Internal Two-Phase Flow within an Aerated-Liquid Injector and its Injection into the Corresopnding High-speed Crossflows." NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-09162002-133800/.
Повний текст джерелаKoen, Devan. "Investigation of novel cooling methods to enhance aerospace component manufacturing practices." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/18058.
Повний текст джерелаENGLISH ABSTRACT: The aerospace industry actively pursues innovation, especially in materials and their use in new applications, to improve their aircraft as well as their competitive position. Ti-6Al-4V has been available now for more than 50 years. Yet, in the new generation of aircraft using structural composites, a dramatic increase in the proportion of Ti-6Al-4V will be seen along with emerging application in automotive and chemical industries. This material possesses superior material properties compared to conventional materials such as steel and aluminium, although it is at the expense of machinability. Researchers are therefore actively searching for improved cutting technologies to improve production rates for Ti-6Al-4V. At higher cutting speeds than the industry norm of 60 - 90 m/min, machining becomes a challenge, resulting in low productivity on titanium parts. The limiting factor in the machining of Ti-6Al-4V is high tool temperatures of the order of 1000oC, caused by its resistance to absorb heat and good mechanical strength at elevated temperatures. The result is extreme temperatures that are concentrated on the cutting edge of the tool. The challenge to improve the tool life is therefore focused on removing heat from the insert. Liquid nitrogen was identified as a good candidate as coolant with the additional advantage of being environmentally friendly. The research presented investigates the use of a gravity feed enclosed liquid nitrogen cooling system to improve the tool life of the cutting inserts. The liquid nitrogen is contained on the insert rake face by means of a tool cap. To improve the effectiveness of the cooling method, a polycrystalline diamond (PCD) insert was used. This insert has a considerably higher thermal conductivity that aids in cooling the cutting edge. Tungsten carbide inserts are used for benchmark testing. The round tungsten carbide inserts with conventional cooling performed exceptionally well for machining titanium compared to square inserts, yielding exceptional tool life improvements while significantly increasing the material removal rate. Positive results were recorded with the liquid nitrogen cooling system when used with the polycrystalline diamond cutting insert. A number of far reaching performance issues are identified relating to the design of the tool cap that hindered clear scientific outputs. From a research perspective, the project makes a contribution to the knowledge base in this field. Additionally a new approach in cooling was investigated, resulting in clear indications of design changes required.
AFRIKAANSE OPSOMMING: Die lugvaart industrie streef aktief innovasie na, veral op die gebied van materiale en hul gebruike, om hul vliegtuie en kompeterende posisie in die mark te verbeter. Ti-6Al-4V is al vir meer as 50 jaar beskikbaar. ‘n Drastiese verhoging in die aanvraag na Ti-6Al-4V deur die lugvaart, motor en chemiese industrieë word verwag wanneer die volgende geslag vliegtuie wat koolstofvesel as strukturele materiaal begin gebruik, in produksie gaan. Die materiaal het beter materiaaleienskappe as konvensionele materiale soos staal en aluminium, maar dit kom egter teen die prys van masjieneerbaarheid. Ti-6Al-4V se masjienering bo die industrie norm van 60 – 90m/min is ‘n groot uitdaging. Navorsers soek daarom deurentyd na verbeterde sny tegnologieë om die produksie tempo van Ti-6Al-4V te verbeter. Die beperkende faktor vir Ti-6Al-4V masjienering is die temperatuur wat genereer word. Die weerstand van die materiaal om hitte te absorbeer en sy goeie meganiese eienskappe veroorsaak dat temperature in die beitel 1000oC bereik. Hierdie temperature word egter op die snykant van die beitel gekonsentreer. Die uitdaging is dus om hierdie temperature in die beitel te beheer. Vloeibare stikstof is geïdentifiseer as ‘n goeie kandidaat vir verkoeling met die bykomende voordeel dat dit omgewingsvriendelik is. Die navorsing wat hier uiteengesit word, ondersoek die gebruik van ‘n geslote kamer beitelverkoelingstelsel wat deur gravitasie met vloeibare stikstof voorsien word om die beitel leeftyd te verbeter. Die oppervlak van die beitel word in hierdie konsep direk aan die vloeibare stikstof blootgestel. Om die effektiwiteit van die stelsel te verbeter word van PCD beitels gebruik gemaak. Die beitel se verbeterde hittegeleidingsvermoë help om die beitel se snykant koel te hou. Tungstenkarbied beitels word gebruik om ‘n standaard te stel vir eksperimentele analise. Die ronde tungstenkarbied beitels en konvensionele verkoeling het verstommend goed presteer vir Ti-6A-4V masjienering in vergelyking met vierkantige beitels. Die materiaalverwyderingstempo is aansienlik verhoog sonder om die beitel se leeftyd in te boet. Positiewe resultate is waargeneem met die vloeibare stikstof sisteem saam met die PCD beitels. ‘n Aantal verreikende uitdagings is geïdentifiseer wat suiwer wetenskaplike afleidings bemoeilik. Hierdie probleme kan almal aan die ontwerp van die toerusting toegeskryf word. Die werk lewer egter steeds ‘n bydrae tot die kennis in die veld. ‘n Bykomende benadering vir verkoeling is ondersoek wat duidelik ontwerp-veranderings aandui.
Scott, Drew. "Decomposition Methods for Routing and Planning of Large-Scale Aerospace Systems." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1617108065278479.
Повний текст джерелаCirillo, Giovanni. "Space Surveillance and Tracking Tool: Implementation and Test of New Methods." Thesis, KTH, Rymdteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-262030.
Повний текст джерелаI mars 2019 uppgick antalet konstgjorda föremål större än 1 mm i omloppsbana runt jorden till över 170 miljoner. Av dessa är endast en mycket liten andel (0.03%) katalogiserade. En kollision mellan en operativ satellit och ett annat föremål i bana kan helt eller delvis förstöra satelliten. För att reducera risken för kollisioner är det därför viktigt att katalogisera så många föremål som möjligt. Detta görs genom att använda programvaran "Space Object Observations and Kalman Filtering" (SPOOK), som utvecklats av företaget Airbus Defence and Space i Friedrichshafen, Tyskland. Målet med detta examensarbete var att skapa nya funktioner i programvara samt att förbättra de befintliga funktionerna. Tre huvudmål har uppnåtts: • En ny modell för ljusförhållandet har skapats för att ta hänsyn till ocklutationen av solen på grund av en täckande kropp (till exempel jorden eller månen) och dess påverkan på solstrålningstrycket på rymdfarkosten, vilket är nödvändigt för att ha en bra modell för hur omloppsbanan fortplantas • En algoritm för s.k. tracklets, flera observationer av samma föremål längs dess omlopp, har skapats i syfte att skilja mellan olika tracklets som utgångspunkt för bestämma vilka mätningar som tillhör samma föremål vid avlägsna epoker. Detta är nödvändigt för att korrekt kunna uppdatera katalogen över rymdföremål. • Modellen för att ta hänsyn till processbruset har förbättrats och förslag ges om hur man ställer in olika parametrar för olika slags omloppsbanor.
Fang, Zigang 1958. "A CHEMKIN based Fortran simulation code for the laminar opposed jet diffusion flame." Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/291383.
Повний текст джерелаSalud, Ellen. "Developing a library of display effects on pilot performance| Methods, meta-analyses, and performance estimates." Thesis, San Jose State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1547139.
Повний текст джерелаThe design of NextGen and current-day cockpit displays are critical for efficient pilot performance and situation awareness on the flight deck. Before deployment of a design into the cockpit the costs and benefits that a display design imposes on performance and situation awareness should be considered. In this thesis, a design tool was developed to support the design of NextGen displays for situation awareness and performance. This design tool is a library of pilot performance estimates. Through literature reviews and meta-analyses of empirical data, the library was developed to provide display designers 1) qualitative distinctions of display properties that either support or limit full situation awareness, and 2) quantitative performance time estimates until situation awareness as a function of various display formats. A systematic method was also developed for future augmentation of the library.
Masi, Barbara Ann. "Fabrication methods and costs for thermoset and thermoplastic composite processing for aerospace applications." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/72739.
Повний текст джерелаBarrére, Vincent. "Viability of CREO Simulate : (CAD software’s module) as a thermal simulation software." Thesis, KTH, Flygdynamik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-261206.
Повний текст джерелаGeller, Benjamin M. "Methods for advancing automobile research with energy-use simulation." Thesis, Colorado State University, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3635614.
Повний текст джерелаPersonal transportation has a large and increasing impact on people, society, and the environment globally. Computational energy-use simulation is becoming a key tool for automotive research and development in designing efficient, sustainable, and consumer acceptable personal transportation systems. Historically, research in personal transportation system design has not been held to the same standards as other scientific fields in that classical experimental design concepts have not been followed in practice. Instead, transportation researchers have built their analyses around available automotive simulation tools, but conventional automotive simulation tools are not well-equipped to answer system-level questions regarding transportation system design, environmental impacts, and policy analysis.
The proposed work in this dissertation aims to provide a means for applying more relevant simulation and analysis tools to these system-level research questions. First, I describe the objectives and requirements of vehicle energy-use simulation and design research, and the tools that have been used to execute this research. Next this dissertation develops a toolset for constructing system-level design studies with structured investigations and defensible hypothesis testing. The roles of experimental design, optimization, concept of operations, decision support, and uncertainty are defined for the application of automotive energy simulation and system design studies.
The results of this work are a suite of computational design and analysis tools that can serve to hold automotive research to the same standard as other scientific fields while providing the tools necessary to complete defensible and objective design studies.
Lloyd, Jennifer A. "Numerical methods for Monte Carlo device simulation." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12766.
Повний текст джерелаIncludes bibliographical references (leaves 51-53).
by Jennifer Anne Lloyd.
M.S.
Staniszewski, Marcin. "Simulation of tri-axially braided composites half-cylinder behavior during balistic [sic] impact." Akron, OH : University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1177978645.
Повний текст джерела"May, 2007." Title from electronic thesis title page (viewed 4/28/2009) Advisor, Wieslaw K. Binienda; Committee members, Craig C. Menzemer, Ala Abbas; Department Chair, Wieslaw K. Binienda; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.