RANS investigation of incoming vortex on the tip leakage vortex breakdown in an aspirated compressor cascade

Abstract

Boundary layer suction is an efficient method for mitigating flow separation and enhancing the performance of a highly loaded compressor cascade. Nevertheless, in a compressor cascade with tip clearance, the high adverse-pressure gradient induced by suction can exert a negative impact on tip leakage vortex (TLV), leading to tip leakage vortex breakdown (TVB). In order to control TVB and enhance its performance, a vortex generator (VG) has been employed in an aspirated compressor cascade. The effect of the swirling direction of the incoming vortex induced by VG, suction flow rate, tip clearance size, and solidity were also investigated. The results reveal that TVB can occur even in a conventional compressor cascade with suction. For the newly designed compressor cascade, TVB can occur without suction, and the introduction of suction enhances TVB. After introducing an incoming vortex, TVB in the aspirated compressor cascade with suction is eliminated. The loss in the aspirated compressor cascade is reduced by 47.1% compared to that in the newly designed compressor cascade. The incoming vortex further reduces the loss by 1% compared to the aspirated compressor cascade due to the suppression of TVB. This outcome can be attributed to the fact that a co-rotating incoming vortex increases the core axial velocity of TLV and reduces its strength, thereby enabling TLV to withstand the high adverse pressure gradient induced by suction. It is worth noting that a counter-rotating incoming vortex enhances TVB, making it an unsuitable design for controlling TVB.