Performance Investigations of Large Capacity Centrifugal Compressors

Abstract

An experimental investigation concerning the optimum relative velocity distribution within impellers, the optimum diffusion ratio of vaned diffusers and the optimum circumferential area distribution, sectional shape of scrolls was carried out using high specific speed shrouded impellers with backward leaning blades. A performance design procedure based on loss analysis and quasi-three-dimensional flow analysis was also developed and modified by introducing experimental results. The design procedure was applied to a 7900-kw four-stage air compressor to demonstrate the usefulness. Field test results of the complete machine showed that the maximum isothermal efficiency was 75 percent with the pressure ratio of 5.96 and the flow rate of 29.3 m3/s.