Mechanism of effect of leading-edge geometry on the turbine blade cascade loss

A research on the flow field around leading-edges of different geometries at design and off design incidence was done. It is found that the elliptical leading-edge exhibits better performance, since the elliptical edge can not only depress the pressure spike to successfully avoid the presence of separation bubble near the leading-edge in wide range of working condition, but also keep the boundary layer almost unchanged small in wide range of incidence. When the positive incidence is large, the separation bubble will emerge at the leading-edge of different shapes, inducing the boundary layer transition, however, the research shows that the elliptical leading-edge will bring about the boundary layer transition at larger incidence. The elliptic leading-edge blade decreased about 7% of profile loss compared to baseline blade profile at the insidence of 20°. The increase of the inlet turbulence intensity could depress but not completely suppress the separation bubble at leading-edge.