Recently, the demand of a highly loaded impeller for industrial compressors is increasing due to environmental and economic reasons. In a compressor aerodynamic design including the matching of an impeller and a diffuser, it is very important to predict the impeller flow field precisely, but due to its high blade loading, a large flow separation and a strong clearance leakage flow occurring inside the impeller passage and impeller exit flow is distorted significantly. Thus it becomes difficult to predict a compressor performance with enough accuracy.
Therefore, in order to validate the prediction accuracy of CFD analysis to the highly loaded industrial compressor impeller, flow measurements at the impeller exit were conducted by using 3 holes yaw meter and hot wire anemometry traverse tests, and compared to the CFD results. CFD analysis was conducted by Iwate University using ANSYS CFX, in which SST model was applied to estimate turbulence intensity.
From the comparison between CFD results and measurements, significant difference in turbulence intensity and flow angles between measurements and CFD results could be observed at the impeller exit. These results imply that the reason behind this difference could be because CFD prediction underestimates the free stream turbulence and mixing effects between free stream and clearance flows.