Effects of Spacing and Geometry of Distributed Roughness Elements on a Two-Dimensional Turbulent Boundary Layer

摘要: Abstract : This thesis is a study of the effects distributed roughness elements on two-dimensional turbulent boundary layer. Measurements were taken total ten rough wall configurations: four involving Gaussian spikes, and six with circular cylindrical posts. Rough flows are particularly suited to Laser Doppler Velocimetry (LDV) due fact that measurements required near solid surface, as well has in highly fluid. The LDV system used this fine resolution (50pm), three-component, fiber-optic system. All mean velocities, Reynolds stresses, triple products measured. unique range variety cases for which data was taken. show flow over characterized by high levels turbulence element peaks at interface between low-speed, near-wall fluid higher speed above. Behind an element, high-momentum sweeps toward wall, there small region ejection low-momentum Cylindrical typically have larger magnitudes stresses their compared elements. Trends velocity profile parameters such displacement height, effect, wake parameter examined respect geometry spacing.