Influence of uncertain inflow conditions on a subsonic compressor cascade based on wind tunnel experiment

Abstract

The intended inflow condition of compressors is subject to the uncertain inflow Mach number ( Ma1) and incidence angle ( i). To quantify the effects of uncertain inflow conditions, real-time measuring experiments of Ma1 and i are performed under various operating conditions to extract the statistical characteristics of the uncertainties. Statistical analysis shows that Ma1 and i follow Gaussian distribution. 0.005 and 0.125 are chosen as the standard deviation of Ma1 and i, respectively. Based on these data, an in-house code of non-intrusive polynomial chaos and Sobol’ indices are employed to quantify the variability in the aerodynamic performance of a compressor cascade caused by uncertain Ma1 and i. The results show that the inflow uncertainties narrow the steady working range of the compressor cascade and lead to fluctuation in the aerodynamic performance. The fluctuation amplitude of the total pressure loss coefficient increases about 15.8 times and tenfold while the static pressure ratio increases just double and 1.3 times under various Ma1 and i conditions, respectively. An analysis of flow field under various operating conditions shows that the uncertainties change the peak isentropic Mach number on the suction surface alter the location and size of the boundary layer separation and reattachment, and shift the interference between the wake and suction surface separation vortex. The sensitivity analysis reveals that as Ma1 increases from 0.5 to 0.6, the dominant parameter affecting the uncertainty of the flow field changes from i to Ma1. When Ma1 increases to 0.75, the coupling effect of Ma1 and i dominates the flow field.