Numerical Investigation of the Flow Field and Aerodynamic Load on Impellers in Centrifugal Compressor With Different Radial Inlets

Abstract

Based on Computational fluid dynamics (CFD) simulation, this study investigates the interior flow in a radial inlet, and helps to figure out the flow phenomenon in radial inlet and the aerodynamic load on the downstream impellers. Three different radial inlets, i.e., original model without guide vanes (OGV), with evenly distributed guide vanes (EGV) and with unevenly distributed of guide vanes (UGV) are considered. The results indicate that the performance of the compressor with UGV outperforms the others, which increases the polytropic efficiency of the centrifugal compressor by 2.3% and provides better flow parameter distribution. The inlet distortion created by the radial inlet affects the aerodynamic load distribution on the downstream impeller. Running unsteady simulations, the aerodynamic load on the impeller’s leading edge is obtained for the three radial inlets. The dominant frequency and pulse amplitude obtained by Fast Fourier transforms (FFT), reveal that the main frequencies of the aerodynamic load present different distributions under three radial inlets. The UGV model provides the minimal amplitude value at machine rotating frequency when compared with the other two models, and the harmonics of the impeller passing frequency appear obviously, which is similar to that under the axial flow inlet condition.