An improved criterion for predicting corner stall in axial compressors with varying dihedral angles

Currently, the design of advanced compressor blades has reached the full Three-Dimensional (3D) modeling stage. When analyzing the reasons for the failure of popular corner stall prediction criteria for axial compressors to predict the corner flow state in modern compressor 3D blades with end-bend and composite bend-sweep characteristics, it is believed that, in addition to the dihedral angle factor in the corner, the variation of the dihedral angle along the flow path is an important factor that has not been considered to date. In light of this, this study first uses the characteristic effects of the diffuser on the deceleration and pressure increase in airflow to design a series of physical models of varying dihedral angle diffusers that are equivalent to compressors. Based on these models, a quantization parameter is established to characterize the development speed of the intersection of boundary layers at the corner under varying dihedral angle and adverse pressure gradient conditions. After combining this with the effects of secondary flow, a Modified diffusion factor DJ (MDJ) is developed to describe the development of corner flow from the leading edge of the blade to its trailing edge under varying dihedral angle conditions. Finally, based on a compressor cascade database, an improved criterion for predicting corner stall in axial compressors using the MDJ diffusion factor is proposed. The validation results, based on extensive experimental data of compressor blades, reveal that this improved criterion can significantly enhance the accuracy of corner stall predictions in the 3D blades of modern compressors compared to currently used prediction criteria, by taking into account the effects of variations in the dihedral angle.