Basic Features of Speed Induced Transient Behaviour of Axial Flow Compressors

An investigation is presented of basic features of speed induced transient behaviours of axial compression system. A non–linear model is developed for prediction of the transient response due to speed variation. Generally, the operating point forms a loop during an accelerating process. A small B or great rate of change in speed leads to a large loop. In the hysteresis region of the characteristic of the compressor, there are four possible solutions: steady flow with the compressor working on the unstalled part of the characteristic; steady flow with the operating point first getting across the stall limit then going back to the initial point; rotating stall and surge. Two critical values of the B parameter are identified, on which the system response depends. They are: Br, at which transition from rotating stall to surge occurs, and Bs, at which that from surge to steady flow takes place. Br and Bs are found to vary with some factors concerned. Their variation with the initial point, rate of the change in speed and the time lag constant are also studied.Copyright © 1990 by ASME