Optimizing the Tip Section Profiles of a Steam Turbine Blading

Though there is not much freedom in shape modification of profiles for tip sections of steam turbines of large output, there is still enough space for optimizing these profiles. The constraints are already in the thermodynamic design of the last stage blading. The layout of the tip cascade indicates that the optimizing strategy should primarily concern the leading edge region and the trailing edge. Proper design can cut down both the front and exit shock wave intensities and the shock wave direct and indirect losses, as well as attenuate the interacting shock waves. This “partial optimization” method has been experimentally verified and is presented in this paper.