Mechanism On The Interactions Of Rotor Tip Flow With Slot-Type Casing Treatment In A Transonic Compressor Stage

Abstract

Aiming to reveal the influence mechanism of casing treatment on rotor tip flow structure, unsteady numerical method was used to study the effects of slot-type casing treatment (SCT) in a transonic compressor. The results showed that the tip flow field appeared obvious periodic flow characteristics with SCT at smooth casing near stall condition. When the rear edge of slot passed through the rotor pressure surface, the tip leakage flow kinked and was sucked into slots, yet significantly weakened when the rear edge of slot passed through the rotor suction surface. Meanwhile, the flow patterns in the slots change periodically with the variation of the relative position of rotor and slots. Furthermore, with the compressor throttling, obvious vortex structure evolution appeared in rotor tip region. At larger mass flow rate, the tip leakage vortex and corner vortex induced by SCT evolved almost at the same time, resulting in a large range of flow field pulsation in the rotor tip region. However, the interaction between corner vortex and tip leakage vortex happens and dominates at lower mass flow rate. As a result, the SCT gradually loses the ability of stability extension.