Reduction of energy loss by bowed blades

The origination and development of major vortexes in turbine cascade were investigated at different attack angles and outlet mach numbers and bowed angles by combining experiments with numerical simulations. By comparing the difference of flow field in bow and straight blade cascade, the effects of blade bowing on the position of saddle point of horseshoe vortex and on the strength and position of the passage vortex were investigated. The effect of blade bowing on the stability of passage vortex was also studied through the analysis of section topology. By analyzing the difference of the contribution of passage vortex to the energy loss under different aerodynamic conditions, it was pointed out that for a cascade with strong passage vortex, the reduction of energy loss was the result of not only the decrease of passage vortex strength due to blade bowing but also the redistribution of boundary layer.