Experimental Investigation and Performance Analysis of Six Low Flow Coefficient Centrifugal Compressor Stages

Abstract

Some results of a research and development programme for centrifugal compressors are presented. Six stage configurations with low flow coefficient were tested. The stages had channel width parameter bo/D2=0.01 and 0.03. For each value of the width parameter three different impellers with inlet hub to outlet diameter ratio do/D2=0.3, 0.4 and 0.5 were designed. Test rig, instrumentation and data analysis are described. Special attention was devoted to probe calibrations and to evaluation of the leakage, bearing and disc friction losses. Aerodynamic performance of all tested stages is presented. Slip factors of impellers obtained experimentally and theoretically are compared. Losses in both vaneless diffuser and return channel with de-swirl vanes are discussed. Rotating stall was also investigated. Criteria for stall limit were tested.