Theses and Dissertations from UMD

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New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

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2011 - 20132

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Author: search.filters.author.Voegele, AndrewSubject: search.filters.subject.LES

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    EXPERIMENTAL AND NUMERICAL INVESTIGATION OF TANGENTIALLY-INJECTED SLOT FILM COOLING
    (2013) Voegele, Andrew; Trouve, Arnaud; Marshall, Andre; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Film cooling is a technique used in gas turbine engines, and blades and rocket nozzles to protect critical surfaces from the hot combustion gases. In film cooling applications, a relatively cool thin fluid is injected along surfaces and subsequently mix with the hot mainstream, thus leading to a reduction of protection at the wall. The breakdown of this film involves complex physics including intense turbulent mixing, heat transfer, conduction, radiation and variable density effects to name a few. In this dissertation, film cooling is both experimentally measured and numerically simulated. The experiments feature non-intrusive Particle Image Velocimetry to provide two-dimensional planes of mean and fluctuating velocity, which are critical in order to characterize and understand the turbulent flow phenomena involved in film cooling. Additionally, through the use of micro-thermocouples, the thermal flow fields and wall temperatures are non-intrusively measured, with very small radiative errors. The film cooling flows are experimentally varied to cover a variety of breakdown regimes for both adiabatic (or idealized walls with no heat loss) and on-adiabatic walls (or walls with a carefully controlled heat loss through them). The subsequent experimental dataset is a unique and comprehensive set of turbulent measurements characterizing and demonstrating the film breakdown and the turbulent flow physics. The experiments are then numerically simulated using an in-house variable density, Large Eddy Simulation (LES) Computational Fluid Dynamics (CFD) code developed as part of this dissertation. In addition to accurately predicting important turbulent kinematic and thermal flow phenomena, the key wall parameters were predicted to within 3% for the adiabatic cases and to within 6% for the non-adiabatic cases, with a few exceptions. Turbulent inflow techniques, crucial for the success of LES of film cooling, are examined. In addition to the turbulent flow physics, radiation and conduction physics at the wall were also simulated with good fidelity. The combined experimental and numerical approach was used to uniquely form a comprehensive study, examining many aspects of film cooling phenomena relevant for engineering applications.
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    Numerical Characterization and Modeling of Adiabatic Slot Film Cooling
    (2011) Voegele, Andrew; Marshall, André W; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Film cooling is a technique used to protect critical surfaces in combustors, thrust chambers, turbines and nozzles from hot, chemically reacting gases. Accurately predicting the film's performance is especially challenging in the vicinity of the wall and the film injection plane due to the complex interactions of two highly turbulent, shearing, boundary layer flows. Properly characterizing the streams at the inlet of a numerical simulation and the choice of turbulence model are crucial to accurately predicting the decay of the film. To address these issues, this study employs a RANS solver that is used to model a film cooled wall. Menter's baseline model, and shear-stress transport model and the Spalart-Allmaras model are employed to determine the effect on film cooling predictions. Several methods for prescribing the inlet planes are explored. These numerical studies are compared with experimental data obtained in a UMD film cooling wind tunnel.