缝式机匣处理对跨声速轴流压气机叶尖流场结构的非定常影响

Aiming to reveal the influencing mechanism of casing treatment on rotor tip flow structures, unsteady numerical method was used to study the effects of slot-type casing treatment in a transonic compressor. The results showed that obvious change of frequency-domain characteristics appeared in the tip flow fields under the effect of casing treatment. At smooth casing, the breakdown of tip leakage vortex and vortex shedding contributed to the unsteadiness of tip flow fields. With casing treatment, the tip leakage flow got motivated and the detached shock moved downstream, which restrained the tip leakage vortex breakdown and induced blockage together. As a result, the excitation frequency of casing treatment played a leading role. Besides, the analysis of vortex structures showed that the interaction of tip leakage vortex and corner vortex significantly varied in different mass flow conditions. At large mass flow rates, the tip leakage vortex and corner vortex induced by casing treatment occurred almost at the same time, resulting in a weak vortex interaction and independent vortex structure. At low mass flow rates, however, the interaction of corner vortex and tip leakage vortex was strengthened. So there existed a strong transition of vortex structure in tip flow fields.