ROTATING STALL IN A SINGLE-STAGE AXIAL-FLOW COMPRESSOR

This paper describes the results on an experimental investigation of r otating stall flow inside a single-stage axial flow compressor: Tests were carried out in two steps. First, measurements were taken to inves tigate the transition process into rotating stall. The compressor star ts into rotating stall via the ''modal route'' with a single rotating stall cell. Further throttling yields to a two-cell shape followed by a significant outlet pressure drop. Both transition processes are disc ussed in detail. Results from the Moore-Greitzer theory are compared w ith measured data. In a second step, measurements were taken to determ ine the three-dimensional unsteady structure of a fully developed rota ting-stall cell. Based on unsteady total pressure and three-dimensiona l her-wire data, the structure of a rotating stall cell could be resol ved in detail upstream and downstream of the rotor. A typical part-spa n stall was Sound. By inserting the measured data into the Euler equat ions, convective and unsteady effects on the pressure fluctuations can be isolated A dependence between the radial flow inside the stall cel l and the unsteady pow accelerations was found.