Browsing by Subject "CFD."
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Item Experimental and numerical investigation of high temperature jet impingement for turbine cooling applications.(2011-05-12T15:42:00Z) Martin, Evan L.; Wright, Lesley Mae.; Engineering.; Baylor University. Dept. of Mechanical Engineering.Modern gas turbine engines commonly operate at temperatures above the melting point of the turbine’s blades and vanes. Internal and external cooling of the blades is required for sustained operation and prolonged engine life. Jet impingement, an aggressive form of cooling, is typically used in the airfoil leading edge which is exposed to extreme heat loads. A parametric study is used to experimentally and numerically investigate high temperature jet impingement in the blade leading edge. The effects of jet Reynolds number (Rejet), jet-to-target surface spacing (ℓ/d), jet-to-jet spacing (s/d), jet-to-target surface curvature (D/d), and jet temperature on stagnation Nusselt numbers are evaluated in a high temperature test apparatus. The facility is validated against correlations developed in previous studies. The experimental study is complimented with CFD simulations performed using commercially available software. Nusselt number results show strong dependence on Reynolds number and geometry yet little or no dependence on jet temperature.Item Large eddy simulation of turbulent flow over transverse variations in aerodynamic roughness length.(2014-09-05) Willingham, David, 1989-; Anderson, William C., 1943-; Mechanical Engineering.; Baylor University. Dept. of Mechanical Engineering.A great deal of literature has been published regarding the impact of complex roughness on turbulent flow. However, the topic of transverse variations in surface roughness, has received relatively little attention. In this thesis, large-eddy simulation is used to investigate the effects on turbulent, high Reynolds number flow, caused by periodic step-changes in aerodynamic roughness length, which persist in the streamwise direction. A parametric study is conducted with respect to the ratio of high to low roughness length and the transverse width of high roughness regions. Results show that lateral momentum flux across shear layers, generates secondary flows in the vicinity of transverse transitions in roughness. These secondary flows form boundary layer scale, counter-rotating vortices, which redistribute turbulence and momentum throughout the entire domain and create time-invariant regions of relatively low and high momentum, above low and high surface roughness, respectively.