Design and Optimization of Variable Radius Fillets Based on the Control of Secondary Flow

Based on the simulation results of Langston cascade, an analysis was conducted on the flow characteristics in the cascade with uniform fillets of different radius, so as to comprehensively evaluate the effects of fillet radius on the flow characteristics in different positions of cascade, and to design and optimize the structure of the variable radius fillet. Results show that with the rise of corner radius in the leading edge of cascade, the diversion capacity increases, and the intensity of horseshoe vortex reduces in the leading edge. The adoption of large radius fillet in the lower side of cascade would intensify the secondary flow and increase the outlet loss of cascade. The intensity of both the horseshoe vortex and the passage vortex could be suppressed by using variable radius fillet, when the increase of the total pressure loss coefficient is inhibited along the flow direction, the entropy increase rate decreases and the flow effectiveness improves.