C. P. No. 609 MINISTRY OF AVIATION AERONAUTICAL RESEARCH COUNCIL CURRENT PAPERS Some Three-Dimensional Effects of Rotating Stall

SUMMARY A small perturbation analysis of rotating stall in inviscid, incompressible flow is developed from an analysis of Yeh. An isolated blade row is considered having a blade height which is not small compared to the msan radius. A criterion is derived for tie occurrence of rotating stall, the speed of stall propagation and the possible number of stall cells involved. From this the frequency of circumferential flow disturbances can be obtained. An example is given of an application Of the analysis. The main assumptions made are that a large number of small amplitude stall cells are induced at onset of stall, that the radial shift of the streamlines is small and that the absolute exit flow angle is small. Possible explanations are suggested for the observed changes in number of stall cells.