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.
Propagation of stall in a compressor blade row
Recent experimental observations on compressors, in particular those of Rannie and Iura, have clarified some features of the phenomenon of stall propagation. Using these observations as a guide, the process of stall in an airfoil cascade has been characterized by a static pressure loss across the cascade which increases discontinuously at the stall angle, the turning angle being affected in only a minor way. Deductions from this simple model yield the essential features of stall propagation such as dependence of the extent of stalled region upon operating conditions, 
the pressure loss associated with stall, and the angular 
velocity of stall propagation. Using two-dimensional approximation for a stationary or rotating blade row, free from interference of adjacent blade rows, extent of the stalled region, the total pressure loss and stall propagation speed are discussed in detail for a general cascade characteristic. Employing these results, the effect of stall propagation upon the performance of a single-stage 
axial compressor is illustrated and the mechanism of entering the regime of stall propagation is discussed. The essential points of the results seem to agree with experimental evidence.
Some Recent Developments in Airfoil Theory
Several recent developments in airfoil and wing theory have as thjeir goals the extension of classical methods to account for characteristically viscous phenomena. Airfoil theory has always recognized the existence of such phenomena as explanations of the presence of circulation and vortex wakes; these new investigations are attempts to include detailed descriptions in theoretical models or to extend classical models into areas of strong viscous effects, such as separation and stalling. Some of these studies follow directly from suggestions made by von Karman, and others are reminiscent of his earlier research. This review is concerned with investigations in four categories: (1) the theory of profiles with boundary layers in steady flow, (2) the theory of profiles with boundary layers in unsteady flow, including extensions of unsteady airfoil theory, (3) the theory of wings with leading-edge separation, and (4) Prandtl wing theory applied to partially stalled wings.