Effects of surface roughness and freestream turbulence on the wake turbulence structure of a symmetric airfoil

Abstract

The effects of surface roughness on the wake characteristics of a simulated turbine airfoil, operating in a compressible, high-speed environment, are studied at different freestream turbulence levels. The effects of these parameters on wake distributions of mean velocity, turbulence intensity, and turbulence length scale, as well as on power spectral density profiles and vortex shedding frequencies are quantified one chord length downstream of airfoil. All profile quantities broaden considerably, with lower peak values, as either the level of surface roughness of the turbulence intensity increases. Non-dimensional vortex shedding frequencies also decrease as either the level of surface roughness or the turbulence intensity increases.