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Aerospace Engineering Commons

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Washington University in St. Louis

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Articles 31 - 42 of 42

Full-Text Articles in Aerospace Engineering

Aerodynamics And Vortex Structures Of A Flapping Airfoil In Forward Flight In Proximity Of Ground, Hang Li May 2017

Aerodynamics And Vortex Structures Of A Flapping Airfoil In Forward Flight In Proximity Of Ground, Hang Li

McKelvey School of Engineering Graduate Student Theses & Dissertations

The traditional flapping wing high lift mechanism research mainly focuses on the wing in unbounded flow. However, the real insect flight includes not only the unbounded flow field but also the near-surface flight. Therefore, research on near-surface flight can help reveal the high-lift mechanism of insect flight and should also be beneficial to the research on Micro-Air-Vehicles (MAV). In this thesis, the flow fields of an airfoil in hover and forward flight are simulated in the presence of ground by newly available function of “dynamic meshing” in ANSYS Fluent is employed. The characteristics of aerodynamics, pressure distribution, and vortex structure …


Design And Computational Fluid Dynamics Analysis Of An Idealized Modern Wingsuit, Maria E. Ferguson May 2017

Design And Computational Fluid Dynamics Analysis Of An Idealized Modern Wingsuit, Maria E. Ferguson

McKelvey School of Engineering Graduate Student Theses & Dissertations

The aerodynamics of a modern wingsuit has been the subject of very few detailed scientific studies to date. The prevailing design process remains the dangerous “sew and fly” method, in which designs are tested when they are first flown. This study utilizes Computational Fluid Dynamics (CFD) tools to analyze the flow field and aerodynamics of an idealized wingsuit, which is designed using Computer-Aided Design (CAD) modeling. The 3D CAD software Autodesk Inventor is used to create the wingsuit model, which is designed with a Gottingen 228 airfoil cross-section and a relatively large planform of aspect ratio 1.3. The commercial flow …


Aerodynamics And Shock Buffet Of A Transonic Airfoil In Ground Effect, Boshun Gao May 2017

Aerodynamics And Shock Buffet Of A Transonic Airfoil In Ground Effect, Boshun Gao

McKelvey School of Engineering Graduate Student Theses & Dissertations

No abstract provided.


Numerical Study Of The Aerodynamics Of Dlr-F6 Wing-Body In Unbounded Flow Field And In Ground Effect, Ning Deng May 2017

Numerical Study Of The Aerodynamics Of Dlr-F6 Wing-Body In Unbounded Flow Field And In Ground Effect, Ning Deng

McKelvey School of Engineering Graduate Student Theses & Dissertations

The main focus of this thesis is on the simulation of flow past a three-dimensional wing-body configuration (DLR-F6) in ground effect; a complex 3D wing-body configuration in ground effect has never been analyzed in the aerodynamics literature to date. For the purpose of validation of the simulation approach, computations are performed for the DLR-F6 wing-body in unbounded flow and are compared with the experimental data. The commercial CFD solver ANSYS FLUENT is employed for computations. Compressible Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with Spalart-Allmaras (SA) and - Shear Stress Transport (SST) turbulence models are solved. The validated code is employed …


Shape Optimization Of Supersonic Bodies To Reduce Sonic Boom Signature, Junhui Li Aug 2016

Shape Optimization Of Supersonic Bodies To Reduce Sonic Boom Signature, Junhui Li

McKelvey School of Engineering Graduate Student Theses & Dissertations

In recent years there has been resurgence of interest by aerospace industry and NASA in supersonic transport aircraft. In recent studies, the emphasis has been on shape optimization of supersonic plane to reduce the acoustic signature of sonic boom resulting from the supersonic aircraft at high altitude in cruise flight. Because of the limitations of in-flight testing and cost of laboratory scale testing, CFD technology provides an attractive alternative to aid in the design and optimization of supersonic vehicles. In last decade, the predictive capability of CFD technology has significantly improved because of substantial increase in computational power, which allows …


Evaluation Of Various Turbulence Models For Shock-Wave Boundary Layer Interaction Flows, Francis K. Acquaye Aug 2016

Evaluation Of Various Turbulence Models For Shock-Wave Boundary Layer Interaction Flows, Francis K. Acquaye

McKelvey School of Engineering Graduate Student Theses & Dissertations

Despite the modeling capabilities of current computational fluid dynamics (CFD), there still exist problems and inconsistencies in simulating fluid flow in certain flow regimes. Most difficult are the high-speed transonic, supersonic and hypersonic wall-bounded turbulent flows with small or massive regions of separation. To address the problem of the lack of computational accuracy in turbulence modeling, NASA has established the Turbulence Modeling Resource (TMR) website and has issued the NASA 40% Challenge. The aim of this challenge is to identify and improve/develop turbulence and transition models as well as numerical techniques to achieve a 40% reduction in the predictive error …


Semi-Empirical Modeling Of Two-Dimensional And Three-Dimensional Dynamic Stall, Ramin Modarres May 2016

Semi-Empirical Modeling Of Two-Dimensional And Three-Dimensional Dynamic Stall, Ramin Modarres

McKelvey School of Engineering Graduate Student Theses & Dissertations

Helicopters are generally limited in their performance by the phenomenon of dynamic stall. The purpose of this work is to develop a method for modeling dynamic stall that is appropriate to preliminary design and flight simulator applications. Unlike other semi-empirical dynamic stall models, the model developed in this thesis, not only counts for the well-known, three-dimensional flow effects on the stalled loads but also captures the secondary vortex-shedding phenomenon that has been seen in experiments. The fundamental physics that modify dynamic-stall behavior and that have been extended from two-dimensional to three-dimensional flow are, namely: 1.) yawed flow, 2.) time-varying velocity, …


The Effects Of Rarefaction And Thermal Non-Equilibrium On A Blunt Body And A Bicone In Hypersonic Flow And Their Shape Optimization For Reducing Both Drag And Heat Transfer, Samuel Gardner Jan 2016

The Effects Of Rarefaction And Thermal Non-Equilibrium On A Blunt Body And A Bicone In Hypersonic Flow And Their Shape Optimization For Reducing Both Drag And Heat Transfer, Samuel Gardner

McKelvey School of Engineering Graduate Student Theses & Dissertations

Design of space vehicles pose many challenging problems due to their hypersonic speeds since they need to travel through different flow regimes due to changes in the density of the atmosphere with altitude. Some of the key characteristics associated with hypersonic flow are extremely high temperatures and heat transfer to the wall of the spacecraft. At these temperatures, the assumption of thermal equilibrium is no longer valid and the effect of rotational non-equilibrium must be included in the modeling of diatomic gas flow. This thesis employs the Navier-Stokes equations, which are modified to include a rotational non-equilibrium relaxation model to …


Shape Optimization Of Busemann-Type Biplane Airfoil For Drag Reduction Under Nonlifting And Lifting Conditions Using Genetic Algorithms, Yi Tian Aug 2015

Shape Optimization Of Busemann-Type Biplane Airfoil For Drag Reduction Under Nonlifting And Lifting Conditions Using Genetic Algorithms, Yi Tian

McKelvey School of Engineering Graduate Student Theses & Dissertations

The focus of this thesis is on the shape optimization of the Busemann-type biplane airfoil for drag reduction under both nonlifting and lifting conditions using genetic algorithms. The concept of the Busemann-type biplane airfoil was first introduced by Adolf Busemann in 1935. Under its design condition at a specific supersonic flow speed, the Busemann biplane airfoil eliminates all wave drag due to its symmetrical biplane configuration; however it produces zero lift. Previous research has shown that the original Busemann biplane airfoil design has a poor performance under off-design conditions as well. In order to solve this problem of zero lift …


Application Of Wray-Agarwal Model To Turbulent Flow In A 2d Lid-Driven Cavity And A 3d Lid-Driven Box, Hakop J. Nagapetyan Aug 2015

Application Of Wray-Agarwal Model To Turbulent Flow In A 2d Lid-Driven Cavity And A 3d Lid-Driven Box, Hakop J. Nagapetyan

McKelvey School of Engineering Graduate Student Theses & Dissertations

In this thesis, various turbulence models are used for simulating internal vortical flow, both turbulent and laminar, with large recirculation by considering the flow in a 2-D lid-driven square cavity and a 3-D lid driven cubic box. The accuracy of the newly developed Wray-Agarwal (WA) one equation turbulence model is compared against two well-known industry standard turbulence models; the Spalart-Allmaras (SA) and the Shear-Stress-Transport (SST) k-ω models. The simulations are performed by numerically solving the Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with WA, SA and SST k-ω models and comparing the results with the available experimental data and Large Eddy …


Evaluation Of The Performance Of Various Turbulence Models For Accurate Numerical Simulation Of A 2d Slot Nozzle Ejector, Colin Graham Aug 2014

Evaluation Of The Performance Of Various Turbulence Models For Accurate Numerical Simulation Of A 2d Slot Nozzle Ejector, Colin Graham

McKelvey School of Engineering Graduate Student Theses & Dissertations

With the development over the last several decades, accurate Computational Fluid Dynamics (CFD) modeling has now become an essential part in the analysis and design of various industrial products where the fluid flow plays an important role. The goal of this thesis is to apply the CFD technology to the analysis of a 2D slot nozzle ejector which has application in Short Take-off and Landing (STOL) aircraft and other future aerospace vehicles. In the nozzle-ejector configuration, the high speed air flow from the nozzle entrains the ambient air into a mixing chamber (ejector) as a means to create additional thrust …


Optimization Of Induced-Power From Dynamic Inflow Theory With Realistic Constraints, Chad File Apr 2013

Optimization Of Induced-Power From Dynamic Inflow Theory With Realistic Constraints, Chad File

All Theses and Dissertations (ETDs)

Finite-state induced-inflow theory is used to develop an analytic formulation for general performance of the lifting rotor with arbitrary loading. The theory incorporates conventional blade-element theory for blade lift and provides the integrated loads and the induced-power of the rotor in terms of an arbitrary number of rotor controls such as conventional collective and cyclic pitch as well as higher harmonic radial and azimuthal pitch. The theory provides the basis for a classical quadratic optimization with realistic constraints that is applied to determine minimum induced-power for a variety of available control combinations, rotor trim constraints, and operating conditions. The findings …