Influence of local surface roughness of a rotor blade on performance of an axial compressor stage

The influence of local surface roughness of rotor blades on the performance of axial compressor stages were investigated through numerical simulation with local surface roughness added on the suction and pressure surfaces of rotor blades of realistic compressor stage NASA Stage35. First of all, the reliability of a commercial computational fluid dynamic code was validated and the computed performance maps showed a good agreement with experimental data from literatures. Numerical results indicated that the increase in surface roughness in most of the local positions may cause the deterioration of compressor stage performance. The amplitude of decrease in compressor performance due to the addition of surface roughness in outer and inner portions of the span and the area near the leading edge of the rotor blades would be much greater than that in the region near the trailing edge. The roughness added to the pressure surface near the leading edge had less impact on the stage characteristics, including the mass flow rate at the choked point. Thus the compressor characteristic got close to that under normal conditions and showed a wider stable operating range. The mass flow in the choked region and the adiabatic efficiency were less affected by the roughness added to the region near the trailing edge of pressure surface from rotor blades. However, this scheme mentioned before would increase the total pressure ratio to some extent, with the adverse effect of adding roughness on the corresponding suction surface.