Numerical Assessment of Roughness Effects on Boundary Layer Development over Adjacent Blades in a Linear Compressor Cascade

Surface roughness is a condition that affects the performance of compressor blades. For instance, erosion, corrosion, and fouling of compressor blades due to particles ingestion can cause surface roughness to increase significantly. Accumulation of these particles, sand, dust and salts alter the blade geometry including the leading edge and the surface roughness. In the presence of rough surfaces, an increase in transport of heat, mass and momentum is generally noticed in a turbulent boundary layer, which sparks off considerable interests in the engineering field. Although surface roughness has been widely investigated during the last decades, both experimentally and numerically, the effect of this phenomenon on the aerodynamic performance of compressor blades is not well understood. In this investigation, assessment of the numerical prediction of surface roughness effects on the turbulent boundary layer over an NACA 65-410 airfoil in a linear cascade is conducted. Most commonly used turbulence models in aerospace industry available in the commercial Navier-Stokes code solver package CD-ADAPCO Star CCM+ are investigated. Preliminary results show that the extensions of the turbulence models to account for roughness effects on the turbulent boundary layer are in good agreement with experimental data for lift coefficients and pressure distribution over the airfoils in case of smooth and rough conditions for a wide range of angles of attack.

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