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

Abstract

Abstract 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.