Effects of bowed blade design on supersonic flow

A bowed blade under the conditions of transonic flow and supersonic flow in an industrial steam turbine is numerically investigated to reveal the mechanism of lowering shock loss for a bowed blade. Analyzing the influence of a bowed blade on a flow field structure, 11 stator schemes of a straight blade and bowed blades are designed with bowed angles of 0°, ±5°, ±10°, ±15°, ±20° and ±25°. The relative bowed height of a blade is 50% span, while blade root and blade tip have the same bowed angle. The results show that a bowed blade changes the shock structure, which is the same under different supersonic flows. It is feasible to conduct supersonic flow design for an industrial steam turbine under the condition that the stage pressure is rather high while the flow is rather small. Under the condition of supersonic flow, a bowed blade enables to decrease energy loss and there exists an optimum value. The energy loss on the supersonic rotor decreases compared with that on subsonic rotor. In the 11 schemes, positively bowed stators exert slight effects on the pressure side of the rotor, while the negatively bowed stators exert obvious effects on both the pressure and suction sides of the rotor.