The effects of bend skewed groove casing treatment on performance and flow field near endwall of an axial compressor

A new type of bend skewed groove casing treatment was designed based on the test results of the axial skewed groove casing treatment. The influences of utilizing it to an isolated axial flow rotor, as well as comparisons between it and the axial skewed groove, have been investigated experimentally. The effects on overall performance of the axial chord of the rotor exposed to the treated area have been examined and the ideal axial position of the casing treatment relative to the rotor leading edge was found. For the tested rotor with the new casing treatment, experimental results showed that significant improvements in stall margin were observed without efficiency penalty (in some axial locations) at two different speeds. Compared with the axial skewed groove casing treatment, the new treated casing at the axial exposure do not increase the secondary circulation in the radial-circumferential plane based on the cross hot-wire measurements under the operating condition of near peak efficiency. This can be considered to be one of many factors that keep the rotor efficiency identical.