摘要
Influences of tip clearance on the tip flow and associated loss mechanism in a contra-rotating axial flow fan hasbeen studied in the paper, based on three dimensional numerical results. The results with different tip clearanceare compared in terms of stage efficiency, relative total pressure loss coefficient, flow angle. It is found that theefficiency of the contra-rotating fan changes almost linearly with increment of the tip clearance, however, efficiencyof the rear rotor is observed to decrease more dramatically than that of the forward rotor given same tipclearance variation. The analysis on the flow structure indicates that the tip region flow field is qualitatively similarin both rotors. However, with the same clearance value, the leakage flow in the rear rotor is effected by a tipleakage vortex of greater intensity caused by relative loading levels and the inter rotor interaction.
