Turbine blade airfoil and turbine blade for axial-flow turbine

摘要

A blade for an axial-flow turbine includes an intrados producing a positive pressure between a leading edge and a trailing edge, and an extrados producing a negative pressure. The intrados is formed at its rear portion with a flat surface portion connected to the trailing edge, and the extrados has a curved surface portion formed at least at a portion corresponding to the flat surface portion. The trailing edge of the turbine blade is pointed at its end. The angle of intersection between the intrados and the extrados at the trailing edge is a right angle or an acute angle. Thus, it is possible to inhibit the flowing of a gas from the intrados at the trailing edge toward the extrados and to decrease the degree of curvature of the extrados at the trailing edge portion to reduce the flow speed, thereby minimizing a shock wave generated at the trailing edge portion to reduce the pressure loss and enhance the performance of the turbine.