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Aerospace Engineering Commons™

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2011

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Articles 361 - 368 of 368

Full-Text Articles in Aerospace Engineering

A Numerical Study Of Novel Drag Reduction Techniques For Blunt Bodies In Hypersonic Flows, Christopher Marley Jan 2011

A Numerical Study Of Novel Drag Reduction Techniques For Blunt Bodies In Hypersonic Flows, Christopher Marley

Masters Theses

"Numerical simulations of a full three-dimensional hemispherical body in hypersonic flow are conducted and innovative techniques involving forward injection of gas from the stagnation point of the sphere are investigated; techniques include annular (ring) and swirled injection both with and without upstream energy deposition. Objectives of the analysis are the assessment of 1) drag reductions achieved on the blunt body (including the detrimental drag effect caused by the forward-facing injection itself) and 2) stability characteristics of the jet. Studies are conducted at free-stream Mach numbers of 10 and 6.5 at standard atmospheric conditions corresponding to 30 km altitude. While centered …

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Computational Investigation Of Plasma Actuator As An Active Flow Control Strategy Of Laminar Separation Bubbles, Justin Roger Aholt Jan 2011

Computational Investigation Of Plasma Actuator As An Active Flow Control Strategy Of Laminar Separation Bubbles, Justin Roger Aholt

Masters Theses

"A parametric computational study designed to examine the plausibility of an external body force generated by active means, such as a plasma actuator, as a means of controlling a Laminar Separation Bubble (LSB) over an airfoil at low Reynolds numbers was conducted. Computational Fluid Dynamics (CFD) was employed to characterize the effect that a body force, localized to a small region tangent to the airfoil surface, might have on an LSB. In this study, the effects of altering the strength and location of the "actuator" on the size and location of the LSB and on the aerodynamic performance of the …

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Quantifying Model Uncertainty Using Measurement Uncertainty Standards, Harsheel Rajesh Shah Jan 2011

Quantifying Model Uncertainty Using Measurement Uncertainty Standards, Harsheel Rajesh Shah

Masters Theses

"Model uncertainty quantification is mainly concerned with the problem of determining whether the observed data is consistent with the model prediction. In real world, there is always a disagreement between a simulation model prediction and the reality that the model intends to represent. Our increased dependence on computer models emphasizes on model uncertainty which is present due to uncertainties in model parameters, lack of appropriate knowledge, assumptions and simplification of processes. In addition, when models predict multi-variate data, the experimental observation and model predictions are highly correlated. Thus, quantifying the uncertainty has a basic requirement of comparison between observation and …

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Heat Transfer Augmentation In Rectangular Ducts Due To Passive Flow Destabilization, James Jackson Tinsley Jan 2011

Heat Transfer Augmentation In Rectangular Ducts Due To Passive Flow Destabilization, James Jackson Tinsley

Masters Theses

"The following thesis documents the comparison of surface enhancements in rectangular ducts for heat transfer enhancement of the air-side of off-road heat exchangers. Two sets of experiments were completed, one utilizing air as the working fluid, and the other utilizing water. Five air geometries and four water geometries were studied, including those with crosswise bumps, longitudinal vortex generators, and a unique rifling geometry. A smooth test section was also tested in the water experiments to verify the experimental setup. Such verification had been performed previously for the air experiments by Rucker [2007]. The experiment involved an applied constant heat flux …

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Balloon Borne Mars Research Platforms, Sean Michael Hancock Jan 2011

Balloon Borne Mars Research Platforms, Sean Michael Hancock

Mechanical & Aerospace Engineering Theses & Dissertations

Aerial platforms can fill a measurement gap between orbiters and rovers, providing planetary scale high resolution in situ measurements, access to scientifically interesting terrain that is either inaccessible or hazardous to rovers, and serve as a planet-wide delivery platforms to deploy surface probes and rovers to areas inaccessible given existing entry, descent, and landing systems. A permanent robotic outpost on the Martian surface can utilize locally-derived hydrogen as a lifting gas for balloon systems deployed from Mars. That approach can simplify the inflation and launch of aerial vehicles while allowing for a long duration deployment campaign that is not constrained …

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Inherent And Model-Form Uncertainty Analysis For Cfd Simulation Of Synthetic Jet Actuators, Daoru Frank Han Jan 2011

Inherent And Model-Form Uncertainty Analysis For Cfd Simulation Of Synthetic Jet Actuators, Daoru Frank Han

Masters Theses

"A mixed aleatory (inherent) and epistemic (model-form) uncertainty quantification (UQ) analysis method was applied to a computational fluid dynamics (CFD) modeling problem of synthetic jet actuators. A test case, (Case 3, flow over a hump model with synthetic jet actuator control) from the CFDVAL2004 workshop was selected to apply the Second-Order Probability framework implemented with a stochastic response surface obtained from Quadrature-Based Non-Intrusive Polynomial Chaos (NIPC). Three uncertainty sources were considered: (1) epistemic uncertainty in turbulence model, (2) aleatory uncertainty in free stream velocity and (3) aleatory uncertainty in actuation frequency. Uncertainties in both long-time averaged and phase averaged quantities …

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Continuous Low Thrust For Small Spacecraft Proximity Operations, James Harris Meub Jan 2011

Continuous Low Thrust For Small Spacecraft Proximity Operations, James Harris Meub

Masters Theses

"Recently, both DoD and NASA have demonstrated increased interest in the development of close proximity operations for space systems. AFRL's Advanced Sciences and Technology Research Institute for Astrodynamics (ASTRIA) has defined several key research topics relevant to military priorities, with one area of critical importance being the inspection and observation of low Earth orbit resident space objects (RSOs). This study investigates the feasibility of using a low-thrust cold-gas propulsion system to effectively and accurately facilitate resident space object inspection. Specifically, this study focuses on the Missouri S&T Satellite mission (M-SAT) as a means to demonstrate autonomous RSO inspection. This paper …

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Shaker Table Vibration Testing Of A Microsatellite, Tonya Michelle Sanders Jan 2011

Shaker Table Vibration Testing Of A Microsatellite, Tonya Michelle Sanders

Masters Theses

"In the satellite development process, structural testing is a means to gain confidence in analytical models and ultimately support qualification of the spacecraft for flight. Vibration testing, in particular, is motivated by the safety considerations of crew or launch personnel, the survivability of delicate hardware and electronics, and the avoidance of large stresses that cause structural fatigue or failure. The subject of this thesis is concerned with the shaker table vibration testing of a microsatellite pair designed and built by students at the Missouri University of Science and Technology in Rolla, Missouri. A finite element model (FEM) used in structural …

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