A New Stage Stacking Technique for Axial-Flow Compressor Performance Prediction

Abstract

Modern through-flow solutions, with allowances for losses, etc., give good predictions around design conditions. They are more difficult to apply effectively when individual blade rows are operating under positive stall, negative stall or choke conditions, as can happen off-design in multistage axial-flow compressors of medium and high pressure ratios. A return has been made at the National Gas Turbine Establishment to stage stacking techniques to help solve the off-design performance problems. Basically a new mean radius or one-dimensional analysis has been developed with particular reference to the stall and choke conditions: corrections are then introduced for radial variations and for stage parameters such as blockage and work done factors. Examples on the use of the technique have been selected to illustrate both its success and difficulties.