Effects of Co- and Counter-Rotating Inlet Distortions on a 5-Stage HP-Compressor

Abstract

The HP-compressor of a twin-spool aero-engine experiences a rotating inlet distortion if a rotating stall in the upstream LP-compressor occurs. This may lead to HP-compressor instability like rotating stall or surge and has even more serious effects on the performance and behavior of the engine than rotating stall in the LP-compressor alone. Studies on compressor flow instabilities are carried out at the 5-stage HP-compressor Rig212, developed in the TurboUnion RB199 jet engine programme. In order to investigate rotating inlet distortions, the axial compressor test facility is equipped with a distortion generator rotating at high speeds in the compressor inlet duct. A disk with a sectorial total pressure loss screen simulates an upstream rotating stall. It produces a rotating inlet distortion with up to 65% of the compressor’s design speed in co- or counter-rotation direction. This paper extends the presentation of first results by Peters et al. [1] and covers both, co- and counter-rotating inlet distortions and their influence on the compressor surge margin. Hot-wire sensor data are analysed to investigate the stall inception process and the response of the compressor flow field to the excitation by the rotating inlet distortion. The experimental detection of aerodynamic eigenfrequencies of the compressor is compared with numerical results from a compressor model developed by Hu and Fottner [2].