Effect of Downstream Potential Flow with Different Strength on Turbine Boundary Layer Flow

In order to design a high-load compact low-pressure turbine, the boundary layer flow on the suction surface of T106A blade was studied under different flow fields. The research is mainly based on numerical simulation with experiments. The numerical simulation uses CFX software and LES model to couple Smagorinsky subgrid model. The experimental verification uses a low speed cascade experimental table. The downstream rod was used to simulate the potential flow generated by the downstream blade, and the downstream potential flow intensity was distinguished according to the axial distance between the downstream rod center and the test blade trailing edge. In this paper, two kinds of downstream potential flow intensities are discussed. It is found through analysis that the boundary layer separation position moves downstream, the reattachment position moves upstream, the turning point moves upstream, and the separation bubble size decreases. The closer the downstream rod is to the blade trailing edge, the greater the pressure fluctuation in the cascade passage and the lower the maximum pressure fluctuation phase. The closer the axial distance between the downstream round rod and the trailing edge of the blade, the larger the fluctuation amplitude of the separation starting position in the flow direction, the smaller the size of the separation bubble, and the smaller the momentum thickness of the trailing edge of the suction surface.