Experimental investigation of flow instability evolution in a low-speed two-stage axial compressor

Abstract

A low-speed two-stage axial flow compressor with inlet guided vane was tested. Based on its performance, the near-stall condition was determined. The transient pressure signals on the casing wall were obtained along the circumferential and axial directions. Data statistics method was applied to analyze the features of the pressure signals on the working conditions. The variance of pressure increased along streamwise direction under the large flow rate condition. Meanwhile, it was influenced by the interaction between the stator and the rotor at the inlet of the second stage as well. On the near-stall condition, a modal wave like signal was found in time domain, whose frequency was about 47% of the impeller rotation frequency, accompanied with a broad-band feature in the low-frequency region. The first-stage rotor was found to stall with the analysis on the variance of the pressure. While there was no obvious unstable character observed in the second stage, the parameter at the inlet of the second stage revealed that the disturbance generated in the first stage was suppressed by the second stage. These signals’ features could be used to predict the appearance of instability in the two-stage axial flow compressor.