Interaction mechanism between incoming vortex and tip leakage vortex breakdown of a compressor cascade

Abstract

Steady and unsteady simulation are utilized to investigate the interaction mechanism between casing incoming vortex and tip leakage vortex breakdown (TLVB). The incoming vortex is introduced by using vortex generator. Pitchwise location effect and rotating effect are firstly investigated at steady condition; then, unsteady investigation is employed based on the steady results. At steady condition, the TLVB can be completely removed by incoming vortex with stagger angle of 72° and pitchwise location of y3 (the pitchwise distance between blade leading edge and trailing edge of vortex generator is a half of pitch). The flow mechanism is that the vortex core of TLV is replaced by incoming vortex, which has higher strength, and the ability of TLV to withstand adverse pressure gradient is increased. Moreover, tip leakage mass flow near leading edge is also increased because of the increase of blade loading, coupled with the moderate adverse pressure gradient, the reduction of TLVB is achieved. The unsteady fluctuation on blade passage mainly caused by the interaction between incoming vortex and TLV near leading edge. The distribution of pressure near blade surface is also periodical disturbed by incoming vortex, and the fluctuation of pressure is mainly induced by incoming vortex.