Loss Production in the Wake of a Simulated Subsonic Turbine Blade

The time-averaged flow in the wake of a model of a turbine blade was surveyed using a three-hole pressure probe; boundary layer traverses were also carried out using a flattened pilot probe. Loss coefficients were derived from the mass-weighted deficit in stagnation pressure. Results showing the progression of loss with streamwise distance along the surface and the wake of the model are presented. It was found that the loss generated in the wake comprised one-third of the profile loss when a well-developed vortex street was present in the wake. This proportion was reduced by increasing the thickness of the suction surface boundary layer, and by simulating the deviation that occurs in a real turbine blade. In both cases the strength of the vortex street was also shown to have been reduced.