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Full-Text Articles in Engineering
Numerical Investigation Of Flow Around A Deformed Vacuum Lighter-Than-Air Vehicle, Jared N. Kerestes
Numerical Investigation Of Flow Around A Deformed Vacuum Lighter-Than-Air Vehicle, Jared N. Kerestes
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This study characterizes the functional dependence of drag on Reynolds number for a deformed vacuum lighter-than-air vehicle. The commercial computational fluid dynamics (CFD) code, FLUENT, is used to preform large eddy simulations (LES) over a range of Reynolds numbers; only Reynolds numbers less than 310,000 are considered. While the overarching goal is drag characterization, general flow-field physics are also discussed, including basic turbulence spectra. All large eddy simulations are preceded by a Reynolds-averaged Navier-Stokes (RANS) simulation using Menter’s shear stress transport (SST) model. The precursor RANS simulation serves to (1) provide realistic initial conditions, (2) decrease the time needed to …
3d Cfd Investigation Of Low Pressure Turbine Aerodynamics, Jacob Andrew Sharpe
3d Cfd Investigation Of Low Pressure Turbine Aerodynamics, Jacob Andrew Sharpe
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A 3-D Reynolds-Averaged Navier Stokes (RANS) model of a highly-loaded blade profile has been developed using a commercial CFD code with an unstructured/structured grid and several different turbulence models. The ability of each model to predict total pressure loss performance is examined in terms of the spanwise loss distribution and the integrated total pressure loss coefficient. The flowfield predicted by each model is investigated through comparisons of isosurfaces of Q criterion to previous Implicit Large Eddy Simulation (ILES) results. The 3-equation k-kl-¿ model was shown to provide the most accurate performance predictions for a baseline 3-D LPT geometry, and was …
Inlet Distortion Effects On The Unsteady Aerodynamics Of A Transonic Fan Stage, Daniel Oliver Reilly
Inlet Distortion Effects On The Unsteady Aerodynamics Of A Transonic Fan Stage, Daniel Oliver Reilly
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A computational study was conducted to understand the influence of aircraft inlet distortion flow on the unsteady aerodynamic loading of a gas turbine fan stage. A single stage, transonic fan design with no inlet guide vanes was modeled with a commercial, computational fluid dynamics solver, STAR-CCM+, using the harmonic balance technique. The baseline inlet boundary condition applied to the model is consistent with that of a homeomorphic variant of the M2129 S-duct, and exhibited stagnation pressure distortion and a swirl pattern. The baseline inlet flow was decomposed and parameterized into a set of inlet boundary conditions which were individually applied …
High-Fidelity Multidisciplinary Sensitivity Analysis For Coupled Fluid-Solid Interaction Design, Koorosh Gobal
High-Fidelity Multidisciplinary Sensitivity Analysis For Coupled Fluid-Solid Interaction Design, Koorosh Gobal
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In many engineering disciplines such as aerospace, marine, automotive, and biomedical engineering, the consideration of the coupling between the fluid and structural systems is necessary for quality engineering analysis. Therefore, the need for such analysis in the design is continuously increasing. The primary motivation for this work is to develop a sensitivity analysis tool that is capable of calculating accurate sensitivities without significant modification of the source codes for simulations based on non-body conformal grids. The majority of work done on the coupled fluid-solid simulations are based on computational grids that conform to solid boundaries. This becomes a restriction for …
Fluid-Structure Interaction Simulations Of A Flapping Wing Micro Air Vehicle, Alex W. Byrd
Fluid-Structure Interaction Simulations Of A Flapping Wing Micro Air Vehicle, Alex W. Byrd
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Interest in micro air vehicles (MAVs) for reconnaissance and surveillance has grown steadily in the last decade. Prototypes are being developed and built with a variety of capabilities, such as the ability to hover and glide. However, the design of these vehicles is hindered by the lack of understanding of the underlying physics; therefore, the design process for MAVs has relied mostly on trial-and-error based production. Fluid-Structure Interaction (FSI) techniques can be used to improve upon the results found in traditional computational fluid dynamics (CFD) simulations. In this thesis, a verification of FSI is first completed, followed by FSI MAV …
Computational Study On Micro-Pilot Flame Ignition Strategy For A Direct Injection Stratified Charge Rotary Engine, Zachary Steven Votaw
Computational Study On Micro-Pilot Flame Ignition Strategy For A Direct Injection Stratified Charge Rotary Engine, Zachary Steven Votaw
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The Office of Security of Defense's Assured Fuels Initiative has recently been pressing for a single fuel battle space. This endeavor requires modifying many of the vehicle power plants currently in operation throughout the Armed Forces. The RQ-7 Shadow, an unmanned aerial vehicle (UAV) utilized by the Marine Corp and Army for reconnaissance purposes, is powered by UEL's AR741 rotary engine and functions on aviation fuel. One effort underway has been focused on developing this rotary engine system to operate on heavy fuels using direct injection technology and charge stratification. Although the rotary engine has many advantages over standard reciprocating …
An Implicit High-Order Spectral Difference Method For The Compressible Navier-Stokes Equations Using Adaptive Polynomial Refinement, Caleb J. Barnes
An Implicit High-Order Spectral Difference Method For The Compressible Navier-Stokes Equations Using Adaptive Polynomial Refinement, Caleb J. Barnes
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A high/variable-order numerical simulation procedure for gas dynamics problems was developed to model steep grading physical phenomena. Higher order resolution was achieved using an orthogonal polynomial Gauss-Lobatto grid, adaptive polynomial refinement and artificial diffusion activated by a pressure switch. The method is designed to be computationally stable, accurate, and capable of resolving discontinuities and steep gradients without the use of one-sided reconstructions or reducing to low-order. Solutions to several benchmark gas-dynamics problems were produced including a shock-tube and a shock-entropy wave interaction. The scheme's 1st-order solution was validated in comparison to a 1st-order Roe scheme solution. Higher-order solutions were shown …