Aerospace Engineering Commons^™

A Parametric Study Of Formation Flight Of A Wing Based On Prandtl's Bell-Shaped Lift Distribution, Kyle S. Lukacovic

Master's Theses

The bell-shaped lift distribution (BSLD) wing design methodology advanced by Ludwig Prandtl in 1932 was proposed as providing the minimum induced drag. This study used this method as the basis to analyze its characteristics in two wing formation flight. Of specific interest are the potential efficiency savings and the optimal positioning for formation flight. Additional comparison is made between BSLD wings and bird flight in formation.

This study utilized Computational Flow Dynamics (CFD) simulations on a geometric modeling of a BSLD wing, the Prandtl-D glider. The results were validated by modified equations published by Prandtl, by CFD modeling published by …

Experimental And Computational Evaluation Of Five Hole Five Probe Flow Analyzer For Subsonic Wind Calibration, Akhila Rupesh Ms, J V Muruga Lal Jeyan Dr

International Journal of Aviation, Aeronautics, and Aerospace

It is very essential to predict the flow and its related parameters to understand real life fluid flow. The real-life fluid problems are studied with wind tunnels which gives very efficient results in practice. But in the case of wind tunnel studies flow angularities plays crucial role. Flow angularity determination includes measurement of static pressure, dynamic pressure and inflow angles. Flow prediction even hold a very strong hand in design process. Designing and testing being the foundation of any process industry, flow measurements and its related parameters have to be well evaluated. In such cases, wind tunnels play important role …

Direct Numerical Simulation Of Roughness Induced Hypersonic Boundary Layer Transition On A 7° Half-Angle Cone, Tara E. Crouch

Theses and Dissertations

Direct numerical simulation (DNS) computational fluid dynamic (CFD) calculations were performed on a 30° slice of 7° half-angle cones with increasing nose radii bluntness at Mach 10 while simulating a distributed roughness pattern on the cone surface. These DNS computations were designed to determine if the non-modal transition behavior observed in testing performed at the Arnold Engineering Development Center (AEDC) Hypervelocity Wind Tunnel 9 was induced via distributed surface roughness. When boundary layer transition is dominated by second mode instabilities, an increase in nose radius delays the transition location downstream. However, blunt nose experiments indicated that as the nose radius …

Schlieren Imaging And Flow Analysis On A Cone/Flare Model In The Afrl Mach 6 Ludwieg Tube Facility, David A. Labuda

Theses and Dissertations

High-speed Schlieren photography was utilized to visualize flow in the Air Force Research Laboratory Mach 6 Ludwieg tube facility. A 7° half-angle cone/flare model with variable nosetip radius and flare angle options was used in the study. Testing was performed at two driver tube pressures, generating freestream Reynolds numbers of 10.0x10⁶ and 19.8x10⁶ per meter. The variable-angle flare portion of the model provided a method for adjusting the intensity of the adverse pressure gradient at the cone/flare junction. As expected from existing literature, boundary layer separation along the cone frustum occurred further upstream as the magnitude of the …

Analytical Models And Control Design Approaches For A 6 Dof Motion Test Apparatus, Kyra L. Schmidt

Theses and Dissertations

Wind tunnels play an indispensable role in the process of aircraft design, providing a test bed to produce valuable, accurate data that can be extrapolated to actual flight conditions. Historically, time-averaged data has made up the bulk of wind tunnel research, but modern flight design necessitates the use of dynamic wind tunnel testing to provide time-accurate data for high frequency motion. This research explores the use of a 6 degree of freedom (DOF) motion test apparatus (MTA) in the form of a robotic arm to allow models inside a subsonic wind tunnel to track prescribed trajectories to obtain time-accurate force …

Wall Model Large Eddy Simulation Of A Diffusing Serpentine Inlet Duct, Ryan J. Thompson

Theses and Dissertations

The modeling focus on serpentine inlet ducts (S-duct), as with any inlet, is to quantify the total pressure recovery and ow distortion after the inlet, which directly impacts the performance of a turbine engine fed by the inlet. Accurate prediction of S-duct ow has yet to be achieved amongst the computational fluid dynamics (CFD) community to improve the reliance on modeling reducing costly testing. While direct numerical simulation of the turbulent ow in an S-duct is too cost prohibitive due to grid scaling with Reynolds number, wall-modeled large eddy simulation (WM-LES) serves as a tractable alternative. US3D, a hypersonic research …

Influence Of Leading Edge Oscillatory Blowing On Time-Accurate Dynamic Store Separation, Ryan G. Saunders

Theses and Dissertations

The primary objective of this research is to support the static and dynamic characterization and the time-accurate dynamic load data acquisition of store separation from a cavity with leading edge oscillatory blowing. Developing an understanding of, and potentially controlling, pitch bifurcation of a store release is a motivation for this research. The apparatus and data acquisition system was used in a two-part experiment to collect both static and dynamic testing data in the AFIT low speed wind tunnel in speeds of 60, 100, and 120 mph, from Reynolds numbers varying from 5.5x10⁴ to 4.6x10⁵, depending on reference …

Initial Stage Of Fluid-Structure Interaction Of A Celestial Icosahedron Shaped Vacuum Lighter Than Air Vehicle, Dustin P. Graves

Theses and Dissertations

The analysis of a celestial icosahedron geometry is considered as a potential design for a Vacuum Lighter than Air Vehicle (VLTAV). The goal of the analysis is ultimately to understand the initial fluid-structure interaction of the VLTAV and the surrounding airflow. Up to this point, previous research analyzed the celestial icosahedron VLTAV in relation to withstanding a symmetric sea-level pressure applied to the membrane of the structure. This scenario simulates an internal vacuum being applied in the worst-case atmospheric environmental condition. The next step in analysis is to determine the aerodynamic effects of the geometry. The experimental setup for obtaining …

Tracking Shock Movement On The Surface Of An Oscillating, Straked Semispan Delta Wing, Justin A. Pung

Theses and Dissertations

A recent research effort, sponsored by the Air Force Office of Scientific Research, numerically investigated the unsteady aerodynamic flow field around an oscillating, straked, delta wing. The study was centered on determining the importance of the unsteady aerodynamic forces acting as a driver for a nonlinear motion known as limit cycle oscillations. The current effort focused on creating a computational model to compare to the results of previous tests and modeling efforts and discover new information regarding the onset of LCO. The computational model was constructed using the Cartesian overset capabilities of the CREATE-AV™ fixed wing fluid dynamics solver Kestrel. …

Comparison Of Flow Field In The Proximity Of A Single Planar & Wrap-Around Fin, Nayhel Sharma, Palak Saini, Hrishabh Chaudhary, Gurteg Nagi, Rakesh Kumar Dr.

International Journal of Aviation, Aeronautics, and Aerospace

Abstract

This paper analyses the results of the computational analysis between a single planar and a wrap-around fin mounted on a semi-cylindrical body. A free-stream Computational Fluid Dynamics (CFD) model was simulated for both cases in the Mach 0.4-3.0M range at 0°Angle of attack, in which, the behavior of flow around the fin was investigated using a turbulence model of higher order discretization. The post-processing shows all the possible views of the flow dynamics around the fins, as well as the missile body. The aerodynamic drag and the rolling moment characteristics of the planar and the wrap-around fin have been …

A Computational Fluid Dynamics (Cfd) Analysis Of The Aerodynamic Effects Of The Seams On A Two-Dimensional Representation Of A Soccer Ball, Allen R. Rohr

Master's Theses

Most major sports today use a dedicated ball or projectile with specific shape, size, and surface geometry, except for soccer. Over the history of the sport, the surface geometry and design stayed relatively unchanged, sewn together using 32 pentagonal and hexagonal panels. However, recent innovations in panel designs differ substantially from the traditional 32 panel ball. The effects these new designs have on the aerodynamic characteristics of the ball have remained largely unknown, even with the influx of experimental research completed in the past decade. Experimental studies have been broad in scope, analyzing an entire ball in wind tunnels or …

Simulation Of Radiation Flux From Thermal Fluid In Origami Tubes, Robert R. Bebeau

USF Tampa Graduate Theses and Dissertations

Spacecraft in orbit experience temperature swings close to 240 K as the craft passes from the shadow of the Earth into direct sunlight. To regulate the craft’s internal energy, large radiators eject unwanted energy into space using radiation transfer. The amount of radiation emitted is directly related to the topology of the radiator design. Deformable structures such as those made with origami tessellation patterns offer a mechanism to control the quantity of energy being emitted by varying the radiator shape. Three such patterns, the Waterbomb, Huffman Waterbomb, and Huffman Stars-Triangles, can be folded into tubes. Origami tubes offer greater control …

A Comparison Of The Aerodynamic Centers For Panel Code Compressible Corrections And Openfoam 5 For Mach 0.1 To 0.8, Dustin Weaver

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

It is known that the aerodynamic center changes from quarter chord to half chord from incompressible to compressible flows on airfoils. Compressible corrections are derived and implemented in a vortex panel code. These results will be used to find the aerodynamic centers for the specified Mach range of 0.1 to 0.8 in 0.1 increments within - 6 to 6 degrees angle of attack. OpenFOAM 5 cases will be created with specific meshes and settings. The results calculated from OpenFOAM 5 will be compared to the results obtained from the compressible corrections.

Effect Of Spalled Particles Thermal Degradation On A Hypersonic Flow Field Environment, Raghava S. C. Davuluri, Huaibao Zhang, Alexandre Martin

Mechanical Engineering Faculty Publications

Two-way coupling is performed between a spallation code and a hypersonic aerothermodynamics CFD solver to evaluate the effect of spalled particles on the flow field. Time accurate solutions are computed in argon and air flow fields. A single particle simulations and multiple particles simulations are performed and studied. The results show that the carbon vapor released by spalled particles tend to change the composition of the flow field, particularly the upstream region of the shock.

Analysis Of Road Vehicle Aerodynamics With Computational Fluid Dynamics, Christian Armando Mata

Open Access Theses & Dissertations

A road vehicles aerodynamics can be one of the most influential aspects of its performance. With the increased importance on fuel efficiency in recent years, new road vehicles are being developed smaller in size, with smaller displacement engines, as well as with improved aerodynamics. The aerodynamics of a vehicle can have a significant effect on its fuel efficiency, as well as other important aspects of the vehicles performance such as the top speed, acceleration, and handling. A study focusing on analyzing aerodynamic effects due to vehicle geometries such as wheels covered by the vehicles body in comparison to open wheels …

Design And Experimental Investigation Of An Oxy-Fuel Combustion System For Magnetohydrodynamic Power Extraction, Manuel Johannes Hernandez

Open Access Theses & Dissertations

A general consensus in the scientific and research community is the need to restrict carbon emissions in energy systems. Therefore, extensive research efforts are underway to develop the next generation of energy systems. In the field of power generation, researchers are actively investigating novel methods to produce electricity in a cleaner, efficient form. Recently, Oxy-Combustion for magnetohydrodynamic power extraction has generated significant interest, since the idea was proposed as a method for clean power generation in coal and natural gas power plants. Oxy-combustion technologies have been proposed to provide high enthalpy, electrically conductive flows for direct conversion of electricity. Direct …

Computational Fluid Dynamics Simulations Of Oscillating Wings And Comparison To Lifting-Line Theory, Megan Keddington

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Computational fluid dynamics (CFD) analysis was performed in order to compare the solutions of oscillating wings with Prandtl’s lifting-line theory. Quasi-steady and steady-periodic simulations were completed using the CFD software Star-CCM+. Quasi-steady simulations were completed for both twodimensional and three-dimensional setups. The steady-periodic simulations were only performed using a three-dimensional setup. The simulations were performed for nine separate frequencies in a pure plunging setup. An additional four simulations were then completed using a setup of combined pitching and plunging at four separate frequencies. Results from the CFD simulations were compared to the quasi-steady lifting-line solution in the form of the …

Nonlinear Development And Secondary Instability Of Traveling Crossflow Vortices, Fei Li, Meelan M. Choudhari, Lian Duan, Chau-Lyan Chang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Building upon the prior research targeting the laminar breakdown mechanisms associated with stationary crossflow instability over a swept-wing configuration, this paper investigates the secondary instability of traveling crossflow modes as an alternate scenario for transition. For the parameter range investigated herein, this alternate scenario is shown to be viable unless the initial amplitudes of the traveling crossflow instability are lower than those of the stationary modes by considerably more than one order of magnitude. The linear growth predictions based on the secondary instability theory are found to agree well with both parabolized stability equations and direct numerical simulation, and the …

Uncertainty Quantification Integrated To Cfd Modeling Of Synthetic Jet Actuators, Srikanth Adya, Daoru Frank Han, Serhat Hosder

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Point-Collocation Non-intrusive Polynomial Chaos (NIPC) method has been applied to a stochastic synthetic jet actuator problem used as one of the test cases in the CFDVAL2004 workshop to demonstrate the integration of computationally efficient uncertainty quantification to the high-fidelity CFD modeling of synthetic jet actuators. The test case included the simulation of an actuator generating a synthetic jet issued into quiescent air. The Point-Collocation NIPC method is used to quantify the uncertainty in the long-time averaged u and v-velocities at several locations in the flow field due to the uniformly distributed uncertainty introduced in the amplitude and frequency of …

Laminar-Turbulent Transition For Attached And Separated Flow, Qian Zhang

University of Kentucky Doctoral Dissertations

A major challenge in the design of turbomachinery components for aircraft gas turbine engines is high cycle fatigue failures due to flutter. Of particular concern is the subsonic/transonic stall flutter boundary which occurs at part speed near the stall line. At these operating conditions the incidence angle is large and the relative Mach number is high subsonic or transonic. Viscous effects dominate for high incidence angles.

In order to predict the flutter phenomena, accurate calculation of the steady and unsteady aerodynamic loading on the turbomachinery airfoils is necessary. The development of unsteady aerodynamic models to predict the unsteady forces and …

Numerical Investigation Of Second-Order Effects In A Supersonic Boundary-Layer, Timothy R. Membrino

Master's Theses - Daytona Beach

Historically, the study of boundary-layer flows has centered on the analysis of the first-order boundary-layer equations and their application to physical flow problems. However, selected “real-world” boundary-layer flows exhibit significant second-order effects which are neglected by the first-order equations. Full Navier-Stokes solutions are often not merited or desired for these flows. Therefore, the second-order boundary-layer equations provide a compromise.

Few validating comparisons have been attempted between second-order boundary-layer theory and experimental or numerical solutions of compressible viscous flows. Experimental simulations to capture second-order effects are difficult since the desired effects are small and can exist simultaneously, resulting in a neutralizing …

Numerical Analysis Of The Viscous Flow In A Supersonic Diffuser, Sa'ed A'Rafat

Master's Theses - Daytona Beach

The goal of a diffuser is to transform kinetic energy into potential energy with minimum losses in total pressure. Existing supersonic diffusers are based on compression through shock waves. This process is inherently inefficient because of the large losses caused by the shocks. We investigate by means of Computational Fluid Dynamics (CFD) the viscous flow in a supersonic diffuser designed by means of inviscid theory to produce a shock-free isentropic compression. The design is based on the combination of elementary flows. Two simple wave regions connected by a sink flow are used to take a uniform supersonic flow at one …