Asymmetric leading edge design of diffusion cascade based on NURBS

Leading edge has an important influence on aerodynamic performance of diffusion cascade. No distinct designs were performed for two sides of symmetric circular and elliptical leading edge. In order to further improve the diffusion cascade aerodynamic performance, an asymmetric leading edge design method based on the 3rd-order non-uniform rational B-splines (NURBS) curve was developed, which realized the asymmetric leading edge shape while ensuring the continuous curvature. The design method was applied to two particular blades with circular leading edge. Numerical results showed that the total pressure loss coefficient could be reduced by 26.3% and 23.5%, respectively, compared with original blade profiles，and the overall aerodynamic performance was developed. At the inflow angle of 51.83°, compared with the symmetric curvature continuous leading edge blade, the leading edge suction peak intensity was reduced by 13.4%, and the leading edge transition onset was delayed by 4.6% chord length. The diffusion cascade overall aerodynamic performance was better with big inflow angle.