Improving the aerodynamic performance of a high-loading turbine blade by end-wall surface structures

In turbomachinery, the end-wall secondary flow introduces significant aerodynamic penalty, especially for high-loading turbine blade designs. The advances in manufacturing technology offer increased design flexibility, especially on surface structure design and fabrication, opening a new option for secondary flow control. The present combined experimental and numerical study explores the potential aerodynamic performance benefit of end-wall surface structures. Aerodynamic loss measurements were performed by using a five-hole probe in a low-speed wind tunnel. The secondary flow structures of blades with normal and high loading were studied. End-wall surface structures were added to the high-loading blade design to mitigate the secondary flow developments. RANS CFD was conducted with the same inlet and exit boundary conditions measured in the experiments. Both the numerical and experimental results demonstrate that the end-wall surface structures can effectively reduce the secondary flow loss and alleviate the lift-off motion of passage vortex. The working principle of the end-wall structures is revealed through detailed analysis of the end-wall region flow structure. The end-wall structures have to be carefully designed according to the local development of secondary flow, and there is a large space for design optimization.