Experimental Research on Flow Instability Mechanism of a Highly Loaded Axial Compressor

The performance and stable operating range of compressors are critical for the efficient operation of various turbomachinery systems. To reveal the flow instability mechanism of a high-speed and high-loaded compressor, a systematic experimental study on a 1.5-stage high-loaded compressor was conducted in this paper. First, the aerodynamic design and aerodynamic performance evaluation of the compressor were carried out. At 100% corrected speed, the measured choked flowrate, peak efficiency, and stall margin were 4.59 kg/s, 87.1% and 17.5%, respectively. Second, the flow instability mechanism of the highly loaded compressor at different corrected speeds was clarified through the experiments. At 50% corrected speed, the compressor rotor developed from a spike-wave stall precursor to a rotating stall; at 70% corrected speed, the compressor developed directly from a spike-wave precursor to surge; at 90% corrected speed, the compressor has undergone the process of modal wave precursor, spike-wave precursor, and surge. Further, at 70% and 90% corrected speed, a classic surge occurred with surge frequencies of 11.91 Hz and 9.59 Hz, respectively. Through the analysis of short-time power spectrum maximum amplitude, the warning time for the surge was 6.7 ms and 15.6 ms, respectively. Finally, as the compressor throttles to stall/surge conditions, the degree of fluctuation of the autocorrelation coefficient and cross-correlation coefficient increases.