Approach to High Performance Transonic Centrifugal Compressor

Abstract

A single stage transonic centrifugal compressor for a small turbofan engine has been developed. Rig testing has demonstrated 83.2 percents of adiabatic efficiency for 7.5:1 of total to static pressure ratio, using a corrected tip speed of 596 m/sec. This paper mainly presents an impeller blade redesign approach from original blade geometry, based on both experimental and numerical results. An in-housedeveloped Navier-Stokes flow solver has been applied to the impeller redesign process. Taking into a consideration of development schedule, a steady flow solver has been used for the impeller analysis, instead of unsteady stage analysis. As a result, important redesign factors for higher efficiency are leading edge shock control, blade-to-blade loading control and splitter-loading optimization. Also, flow physics on secondary flow mechanism has been captured by the computational analysis and its flow control has been applied to the impeller redesign process. The final stage performance has been achieved using a coupling of a pipe diffuser and an impeller-inducer-bleed system by the rig testing.