Modification of Spalart-Allmaras model with pressure gradientaiming for corner separation flow

For the problem in predicting the corner separation, the Spalart-Allmaras (S-A) model was modified by introducing a normalized pressure gradient into the production term of the eddy viscosity in the model equation. Through the calibration in two series of low-speed compressor cascade cases with corner separation, it was found that compared with the experimental results, the original S-A model got a stronger corner separation and lower wall pressure in the separation zone, while the modified model's results were closer to the experience in the size of the separation zone, the pressure coefficient on the suction and pressure sides, etc. The analysis on the production and dissipation terms of the eddy viscosity in S-A model indicates that the normalized pressure gradient introduced to the production term can recognize the separation zone effectively. It can also change the transportation of the eddy viscosity of the model and enhance the eddy viscosity in the corner separation, bringing about a smaller separation zone, while the prediction in the main flow area in the modified S-A model remains the same as the original S-A model. Thus a better prediction is got.