Numerical study and experimental validation of the performance of two different volutes with the same compressor impeller

Abstract

Volute scroll, conic diffuser, and sudden expansion discharge losses account for 4–6 points of efficiency decrement in a typical centrifugal compressor stage. The flow in a volute is highly complex. It is strongly believed that an understanding of the detailed flow structure in a volute will provide insights on minimizing the losses by isolating the mechanisms that contribute to entropy generation. The result will be a more efficient centrifugal compressor product for customers. This article presents the experimental and numerical investigation on the matching of two different overhung volutes with the same centrifugal compressor impeller. The experimental data were measured from flange to flange initially, and then three Kiel probes were installed at different circumferential pinch locations. At the same time, a detailed numerical simulation of the performance of the two volutes has been carried out. A computational model, using the k-ε turbulence model and wall function, has been used to predict the internal flows of both volutes. Good agreement between experimental data and numerical simulation results is found, except at high mass flowrate. The overall performance of the two volutes was also compared thoroughly.