EXPERIMENTS IN ACTIVE CONTROL OF STALL ON AN AEROENGINE GAS-TURBINE

This paper describes work carried out between 1989 and 1994 to investi gate the application of ''Active Stall Control'' to a Rolls-Royce Vipe r turbojet. The results demonstrate that stall control is feasible and can increase the stable operating range by up to 25 percent of pressu re rise. Stall disturbances were detected using rings of high response pressure transducers positioned at different axial planes along the c ompressor; and processed using a PC-bused data acquisition and control system. Actuation was provided by six hydraulically operated sleeve v alves positioned to recirculate air over all or part of the compressor . Stall was artificially induced using combinations of in-bleed into t he combustor outer casing, fuel spiking, hot gas ingestion, and inlet pressure spoiling, thus replicating many of the transient conditions c ommonly observed to make a compressor prone to stall. Results ale comp ared from a number of stall control strategies including those demonst rated at low speed by Paduano et al. (1993) and Day (1993). Best resul ts were obtained with detection of nonaxisymmetric disturbances couple d with axisymmetric control action. A control system of this type is d emonstrated to be capable of extending the stable engine operating ran ge at all speeds and with each method of inducing stall.