Impact of Surface Roughness on Compressor Cascade Performance

Abstract

This paper presents an experimental investigation of roughness effects on aerodynamic performance in a low-speed linear compressor cascade. Equivalent sandgrain roughnesses of 12 μm, 180 μm, 300 μm, 425 μm, and 850 μm have been tested. In nondimensional terms, these roughnesses represent compressor blade roughnesses found in actual gas turbines. Downstream pressure, velocity, and angle have been measured with a five-hole probe at 0.3 chord downstream of the blade trailing edge. For the tested roughnesses of 180 μm, 300 μm, 425 μm, and 850 μm, the axial velocity ratio across the blade row decreases by 0.1%, 2.1%, 2.5%, and 5.4%, respectively. For the same cases, the exit flow angle deviation increases by 24%, 38%, 51%, and 70%, respectively. Finally, the mass-averaged total pressure loss increases by 12%, 44%, 132%, and 217%, respectively. Also, the loss increases more rapidly in the transitionally rough region. Thus, among the three parameters, the loss responds most sensitively to changes in compressor blade roughness.