Compressor flow instability has become a critical issue affecting the performance of gas turbines. To investigate the stall formation mechanism of multistage compressors under low-speed conditions, detailed experimental measurements and CFD analyses were conducted on a five-stage low-speed axial compressor designed by Harbin Engineering University. Experimental results indicate that the compressor exhibits a stall mode where rotating instability (RI) serves as a precursor to stall. During the throttling process, the first-order frequency of the multimodal RI triggers partial-span stall, which subsequently develops into a full-span stall. The simulation results show that there is a strong backflow effect in the radial flow at the blade tip. The combination of the lateral vortex-induced leading-edge separation flow and the radial backflow at the trailing edge forms a blade-tip recirculation vortex. The continuous high-intensity recirculation vortex leads to severe flow field blockage, which in turn results in tip stall. Therefore, suppressing the radial flow has a significant effect on improving the blade-tip flow and reducing the flow field blockage effect under low operating conditions.
Wang et al. (2025) studied this question.