Numerical Study of the Matching of the Volute With the Last Stages Centrifugal Compressor

The matching of the volute with the last stage of centrifugal compressors was studied in this paper, based on the numerical flow analysis platform developed with the commercial CFD software NUMECA. Detailed flow structures and main sources of the flow losses were analyzed. Main factors affecting the performance were studied. Results indicate that all those factors, such as the cross sectional area variation, the shape of the tongue, the connection of the outlet pipe with the volute, the ratio of the outlet radius of the vaneless diffuser with the impeller radius and the volute orientation, have great influence on the stage performance. Based on the analytic results, structural modifications were proposed and experimented numerically. Final results indicate that the polytropic efficiency can be increased by as much as 4.5%. The optimal matching of the volute and the last stage diffuser were studied and summarized.Copyright © 2008 by ASME