Flow separation control on a highly loaded compressor cascade using endwall synthetic jets

This paper presents flow separation control conducted on a highly loaded compressor stator cascade using endwall synthetic jets. Numerical methods are employed and mechanisms of endwall synthetic jets in improving the cascade performance are discussed in detail. The influence of several actuation parameters is also investigated. Results show that endwall synthetic jets are able to improve the flows in the blade passage significantly, a maximum loss reduction of 21.63% and a pressure rise increment of 5.60% are obtained at design condition. Apart from energizing the low momentum fluid inside endwall boundary layer by streamwise momentum addition, endwall synthetic jets could induce a streamwise jet vortex and impede the transverse movement of endwall boundary layer through upwash and downwash. Hence, at the expense of slightly degraded near-wall flows, the formation and further evolution of passage vortex would be delayed and flows in the midspan region would be improved notably. The effectiveness of endwall synthetic jets relies on the proper selection of actuation position and jet angle. Flow control turns out to be the most efficient when the actuator is positioned at just upstream of corner separation region with a relatively small jet angle, and a large enough injected momentum is also necessary. Additionally, the adaptability of the actuation at off-design conditions is validated in the present study.