Stability Improvement with Slot-Groove Hybrid Casing Treatment in a High-Speed Axial Compressor

This study investigated the impact of slot-groove hybrid casing treatment (CT) on the compressor stability and performance. The experimental and numerical studies were conducted in a high-speed axial compressor rotor. The designed hybrid casing treatment is composed of axial skew slots and circumferential grooves, aiming to combine the advantages of slot CT on improving stability and groove CT on reducing efficiency penalty. The experimental results demonstrate that the hybrid casing treatment can obtain the stall margin improvement (SMI) of 24.74% with the peak efficiency loss (PEL) of 3.68%. The numerical results demonstrate that the SMI and PEL of the hybrid CT are between that of the slot CT and the groove CT. The analyses of the compressor internal flow field demonstrate that the momentum transport effect caused by the hybrid CT can inhibit the development of adverse tip leakage flow (TLF). Consequently, the tip blockage caused by TLF is alleviated and the compressor stability is improved. Unlike the slot CT and the groove CT, the hybrid CT exhibits a combined impact on the tip-flow field, incorporating features of both the slot CT and the groove CT. The stability improvement and efficiency penalty of the slot-groove hybrid CT lies between that of the slot CT and the groove CT.