Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 29 for “"Pressure drag"”.
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Solar radiation pressure, drag and gravitational effects on a dust particle in Earth orbit
… on particle orbits is the solar radiation pressure (SRP), which is defined as the pressure exerted by the photons constituting the light from the Sun. Colombo et. al studied the orbital dynamics of ``smart-dust'' under the effects of SRP and atmospheric drag. The numerical model developed …
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Effect of Passive Clean Air Injection Into the Wake Region of a Moving Ground Vehicle
… is responsible for 70% of the aerodynamic drag when the speed of 90km/h is achieved. The topic of wake region manipulation has been revisited multiple times and with varying techniques. When manipulating the flow utilizing a fully passive method, pressure drag can be reduced, increasing the …
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Pressure Disturbance Upstream of the Boundary Layer Data System
… tools in the prediction of upstream surface pressure disturbance and pressure drag of various instrument excrescence shapes for a small aircraft flight test device called the Boundary Layer Data System (BLDS). Insights on pressure disturbance will serve as a guide for the placement of BLDS …
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Continuum Sensitivity Analysis for Shape Optimization in Incompressible Flow Problems
… maximize quantities such as lift and the lift-to-drag ratio, in a process known as shape optimization. It is the goal of this thesis to develop and apply understanding of mixed finite element method and sensitivity analysis in a way that sets the foundation for shape optimization. The open-source …
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Analysis of a Goldschmied Propulsor Using Computational Fluid Dynamics Referencing California Polytechnic's Goldschmied Propulsor Testing
… boundary layer ingestion technologies to reduce drag and increase propulsor efficiency. The most recent testing, done in 1982, left questions concerning the validity of the results. To answer these questions a 38.5in Goldschmied Propulsor was constructed and tested in Cal Poly's 3x4ft wind …
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Investigation of the Under-Body Flow Field of a Prototype Long-Range Electric Vehicle
… however at the design velocity of 104.6 kph, the drag is 196 N; which requires more battery capacity than the 100 kWh maximum of the baseline model. With a fixed frontal area, drag reduction can come from lowered velocity or reduced CD. CD reduction is attempted in four ways: side skirts between …
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Drag reduction of cube-van through boundary-layer control: wind tunnel experiments and prototype road tests
… control procedures for reduction of the pressure drag of a cube-van. Wind tunnel results, obtained using 1/6th scale models, at a subcritical Reynolds number of 105, suggest that both the Moving Surface Boundary-layer Control (MSBC) as well as the tripping of the boundary-layer using …
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The drag and lift characteristics of a cylinder placed near a plane surface
Surface pressure, drag and lift coefficients have been experimentally determined for a right circular cylinder located near a plane surface and placed in a cross flow of air. Parametric studies were carried out for Reynolds numbers varying from 90,000 to 250,000, three plate lengths and a variety …
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Afterbody drag prediction for conceptual aircraft design
… complexity and the difficulty in afterbody drag prediction. This thesis documents a computationally inexpensive method for estimating the afterbody drag of aircraft during the conceptual design stage. The design and creation of a new hybrid approach to afterbody drag prediction is discussed. …
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Overview of the Skin Friction measurements on the NASA BeVERLI Hill using Oil Film Interferometry
Viscous drag reduction plays a vital role in increasing the performance of vehicles. However, there are only so many measurement techniques that can quickly and accurately measure this when compared to pressure drag measurement techniques. The current study makes use of one of the direct and robust …
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Three-dimensional turbulence mechanisms in a supersonic separated/reattaching longitudinal cylinder wake
… of critical flow properties, such as the low pressure in the separated region. This work was experiment-based, utilizing non-intrusive optical measurement techniques, including stereoscopic particle image velocimetry (SPIV), which measures all three components of velocity along a large planar …
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Experimental aero-acoustic assessment of swirling flows for drag applications
The need for quiet drag technologies stems from stricter requirements for and growing demand of low-noise aircraft. The research presented in this thesis regards the use of swirling exhaust flows capable of generating pressure drag quietly by establishing a steady streamwise vortex. The simple …
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Design and Validation of a Force Measurement System for the Analysis of Airfoil Lift and Drag Characteristics
… to reduce the flow separation and therefore the pressure drag generated by a wing section, through the adding of surface modifications. The modifications consisted of roughening the surface of polystyrene airfoils using a sand blasting technique, which resulted in a dimpled surface. This idea …
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Boundary-layer control of bluff bodies with application to drag reduction of tractor-trailer truck configurations
… concepts of boundary-layer control for the drag reduction of bluff bodies is studied experimentally. The methods are: (i) Moving Surface Boundary-layer Control (MSBC) involving momentum injection through one or more rotating elements (light hollow cylinders); and (ii) tripping of the …
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Experimental Investigation of the Active Flow Control on a Two-Dimensional Wind Turbine Airfoil
… were carried out utilizing surface dynamic pressure sensors, a force balance and Particle Image Velocimetry (PIV) flow field measurement techniques. The results show that the fluctuating loading generated by an upstream cylinder wake was reduced by up to 12% using a proportional closed loop …
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The Rough Wall High Reynolds Number Turbulent Boundary Layer Surface Pressure Spectrum
… very few studies investigating the rough wall pressure spectra under fully rough flows, which are relevant to many common engineering applications operating within this regime. This investigation uses the Virginia Tech Stability Wind Tunnel to perform experiments on a series of high Reynolds …
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Aerodynamics study of the flowfield at a shelterbelt
… the help of the aerodynamic parameters, normal pressure drag and skin friction drag. The results obtained from this newly developed numerical scheme show satisfactory agreement with both field experiments and other numerical simulations. In addition, this procedure offers a generalized technique …
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Supermaneuverable perching
… maneuver to land on a power-line by exploiting pressure drag on its stalled wings and tail. We present a feedback controller capable of stabilizing the maneuver over a wide range of flight speeds and quantify its robustness to wind-gust disturbances. In order to better characterize the …
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Aeroelasticity of Morphing Wings Using Neural Networks
… to do so needs to be minimized. The adverse pressure drag as a result of this bump needs to be controlled so that the loss in lift over the wing is made minimal. The design of such a "spoiler bump" on the surface of the airfoil is an optimization problem of maximizing pressure drag due to …
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Advances in the visualization and analysis of boundary layer flow in swimming fish
In biology, the importance of fluid drag, diffusion, and heat transfer both internally and externally, suggest the boundary layer as an important subject of investigation, however, the complexities of biological systems present significant and unique challenges to analysis by experimental fluid …
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