Numerical analysis of the effect of secondary flows in an axial compressor rotor for stability improvement by using casing treatment

The numerical studies for the transonic axial compressor rotor 37, designed by NASA as a test case, were carried out in this study. The flows occurring between the blade tip and the passages have a three-dimensional and complex flow structure, and this complex flow was analyzed using Computational Fluid Dynamics.In this study, the boundary conditions published by NASA for Rotor 37 were first applied to the model and the fluid domain was created, and then the compatibility of this fluid domain with the original case was tested. In this testing process, five different mesh structures were examined and the most compatible mesh structure was selected. During the analysis, SST k-ω turbulence model was employed. The studies for the goal of comparison with the NASA test case results were carried out and it was found that our results agree well with the NASA test results. By analyzing the fluid domain, the near mass flow and peak efficiency points of Rotor 37 were determined. Then, the near-stall and near- design Mach number contour distributions of the smooth case, which is the considered as the test case in this study, the velocity contours, the entropy differences between the blades, and the pressure distributions at the suction and pressure surfaces of the blade were examined. After these analyses, a total of 3 different groove geometries (semi- circular, rectangular and triangular) applied to the smooth case were analyzed and Mach number distribution at near stall condition, velocity streamlines in the groove, entropy distribution at near peak efficiency, blade loading chart were performed and the results were compared with the smooth case. As a result of the analysis of all cases, stall margin improvement and peak adiabatic efficiency charts were created. In addition, total pressure ratio-normalized mass flow and adiabatic efficiency- normalized mass flow graphs were created.