Time Resolved Measurements in an Annular Compressor Cascade With High Aerodynamic Loading

Abstract

In order to identify unsteady flow phenomena this paper presents experimental investigations inside an isolated compressor cascade under off-design conditions. The results of extensive time resolved measurements, which were performed by piezo-resistive pressure sensors and hot wire anemometry show an interaction of aerodynamic and acoustic mechanisms. For a certain operating range the measurements indicate, that vortices, caused by boundary layer separations, oscillate with the pipe mode of the test section. In addition so-called rotating instabilities occur at high blade loading. They rotate with 48% of the circumferential component of the inlet velocity.