A Prediction Model for Corner Separation/Stall in Axial Compressors

Abstract

Endwall corner stall can cause significant aerodynamic blockage and losses production. Hence, pre-prediction of it during the preliminary processes of compressors is important. However, Lieblein’s diffusion factor often fails near the endwall region for the strong three-dimensionality flow effects. A new model for predicting endwall corner stall phenomenon in axial compressors was developed based on the methodology used by Lei et al. [1] (J. Turbomach. 2008, 031006). At first, the influencing factors for the flows of endwall corner separation/stall were analyzed by numerical simulations. The results showed that, besides the parameters determining the loading of a two-dimensional blade profile, blade aspect ratio was also a key factor. Then, by using both the theoretical and empirical methods, a modified diffusion parameter, which can be used as a criterion for axial compressor corner stall, was defined to consider the combined effects of three factors: the streamwise pressure gradient, the circumferential pressure gradient and the passage mass-flow-rate redistribution effect (controlled mainly by blade aspect ratio). Finally, the stall criterion was validated by experimental results of various test facilities with different blade geometries and experimental conditions. The results showed that the modified diffusion parameter can predict the corner separation/stall flows in a good agreement with the experimental results in axial compressors without blade three-dimensional designs.