Turbulent Transonic Flow Over Smooth and Rough Circular Arc Bumps in a Freestream

Abstract

Turbulent transonic freestream flow over a plane smooth surface embedded with smooth and rough circular arc bumps is computed and analyzed using the   k turbulence model to determine the global effect of surface roughness on the shock/boundary layer interaction. Computations are done for various freestream Mach numbers, equivalent sand grain surface roughness heights of the bump, and radius of the bump. The influence of the increase in surface roughness height transcends over onto the shock boundary layer zone and the observations are discussed. It is observed that the surface roughness causes upstream movement of the shock, increases the skin friction coefficient, extends the separation length, reduces the pre-shock Mach number, and enhances the shock/boundary layer interaction zone.

Effect of Cascade Surface Roughness on Boundary Layer Flow Under Variable Conditions

“…The displacement thickness and momentum thickness at the leading edge of the cascade decrease with the increase of roughness and show a trend of decreasing first and then increasing in the latter half. When the roughness is 74 μm, the displacement thickness, momentum thickness, and shape factor at the back of the cascade are the minimum (Wu and Piomelli, 2018;Rodriguez et al, 2017;Butler and Wu, 2018;Nyantekyi-Kwakye et al, 2019;Mendonca and Sharif, 2010;Xu et al, 2020;Zhou et al, 2021;Spalart and Watmuff, 1993;Li et al, 2020;Lee et al, 2018;Schlichting, 1936;Atmani et al, 2009;Goldfeld and Orlik, 2005;Back et al, 2009).…”