Experimental and Numerical Characterization of the Performance of a Transonic Axial Compressor Subject to Inlet Distortion

Abstract The results of an experimental and numerical investigation of a transonic axial compressor subjected to a 120° circumferential inlet distortion are presented in this work. The performance characteristics of the rotor subjected to inlet distortion were significantly different from the performance characteristics when subjected to uniform inlet conditions at 70% corrected speed. Radial flow redistribution, circumferential flow redistribution, and passage unsteadiness were speculated to be the causes of the differences observed, and were investigated using 2D unsteady CFD of the rotor at 50% span. The numerical results agreed qualitatively with the experimental results at 50% span, indicating radial flow redistribution is not the main cause of the compressor’s response to distortion. The numerical results were used to characterize the upstream influence of the rotor on the inlet boundary condition. Significant changes in circumferential profiles of static and stagnation pressure, axial Mach number, and absolute and relative flow angles were observed as the flow approached the rotor leading edge. Passage unsteadiness was quantified by comparison between the flow field of the distorted case and the uniform inlet case near the leading and trailing edges of the rotor. Various analytical expressions were considered to model the effects of distortion with unsteady passage flow and compared with unsteady CFD.