Influence of Strong Pulsation on Stall Onset of a Transonic Compressor

In highly loaded transonic compressors, strong pulsation appears in the flowfield before stall onset. However, the connection between strong pulsation and stall triggering remains unclear. This study adjusts the pulsation intensity before stall in a transonic compressor by modifying the axial spacing between the inlet guide vane and the downstream rotor and investigates its impact on the compressor’s stability. Numerical simulations are conducted to obtain the stability boundaries and stall evolution processes for two configurations with different interaction intensities. The results show that strong pulsation before stall can alter the compressor’s stable operating range. During the stall evolution process, the amplitude of the unsteadiness composed of components with frequencies below 0.5 times the blade pass frequency gradually increases. This corresponds to the decrease in the oscillation frequency and the increase in the oscillation range of the suction-side leading-edge separation bubble at the blade tip, ultimately triggering stall. The difference in the stability boundaries of the two configurations is attributed to the pressure pulsations induced by inlet-guide-vane–rotor interaction, which modify the development of low-frequency oscillations of the blade-tip suction-side separation bubble.