Investigation of the two-dimensional performance of supersonic impulse turbine blade cascades. II - Flow and losses in blade passage and some design criteria

The efficiency of supersonic blade cascades for an impulse turbine designed by the conventional methods is not so high as expected because of the boundary layer separation. In this investigation, for improvement of the efficiency of the supersonic blade cascade, some important problems, such as accurate prediction of the starting Mach number and prevention of the boundary layer separation, are discussed based on the measurements and analysis of the flow in the blade passages designed by the free vortex flow method, which is one of the conventional methods. As the result, some design criteria are proposed.