Browsing by Subject "Fluid mechanics."
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Item Convection from manufactured ice roughness with varying flux boundary conditions.(2014-09-05) Walker, Christopher Wade.; McClain, Stephen Taylor.; Mechanical Engineering.; Baylor University. Dept. of Mechanical Engineering.It is well understood that aircraft wing icing adds weight, increases drag coefficients, decreases lift coefficients, and reduces stall margin, which can lead to aircraft accidents. To predict the shape of these ice accretions, codes, such as the NASA LEWICE code, have been created that step through time and solve an energy balance for an iced airfoil. A critical part of this energy balance is convection over the initial ice roughness. However, determining the convective heat transfer over the initial ice roughness is difficult. Previous methods have been developed for measuring the convective heat transfer for ice roughness with constant thermal boundary conditions. This work investigates the effect of variable heat flux boundary conditions on convective heat transfer, and improves upon the techniques used to obtain convective heat transfer measurements for realistic ice roughness patterns.Item Experimental and numerical study on flow control using obliquely aligned elements.(2010-06-23T12:33:08Z) Narvaez, Gilberto.; McClain, Stephen Taylor.; Engineering.; Baylor University. Dept. of Mechanical Engineering.The use of micro-electromechanical system devices (MEMS) have been studied extensively in literature for control of flow separation and transitioning to turbulent flow. However, there is limited information about how obliquely aligned roughness elements affect the boundary layer development and induce turbulence. The purpose of this study was to measure the transverse flow and turbulent intensities produced by an array of 0°, 5°, 10°, and 15° obliquely-aligned elliptical control elements in turbulent flow at 2, 5, and 10 m/s on a flat plate. The resulting boundary-layer measurements demonstrate the ability of the control elements to produce tailored secondary flows. Since the test coupon was of finite span, results demonstrate that controlled vortices can also be generated using the arrays. Additionally, CFD simulations were performed and compared to the experimental results using the realizable k-ε turbulence model in ANSYS FLUENT 12.0 with solutions converging to residuals less than 1x10⁻⁶ for flow and turbulence quantities.