Effects of Stall Precursor-Suppressed Casing Treatment on a Low-Speed Compressor With Swirl Distortion

Swirl inlet distortion is usually encountered in modern flight vehicles since their inlet ducts usually consist of one or two bends, such as S-inlet duct. An experimental device is first designed to simulate the swirl inlet distortion and then used to test the effectiveness of a novel casing treatment (CT) on a low-speed compressor under the swirl distortions of various intensities. The influences of co- and counter-rotating swirl inlet distortion on the test compressor and the stabilization ability of this novel CT are well demonstrated by the illustrations of static pressure rise curves and efficiency curves. The dynamic prestall pressure signals are also captured to reflect the perturbation energy in the flow field through which the mechanism of the novel CT will be indicated. The relevant results show that counter-rotating swirl distortion in small intensity could increase the compressive ability of compressor with small efficiency loss, and the co-rotating swirl distortion always brings about detrimental effects on compressor performance. At the same time, the distortion of twin swirls can cause nonuniform total pressure profile which can seriously damage the compressor performance. Besides, the stall precursor-suppressed (SPS) CT shows a good capability of stall margin (SM) enhancement no matter what swirl inlet distortions are encountered in the test compressor.