Film Cooling Effectiveness Downstream of Optimised Cross Corrugated Slot Geometry with Exit Shaping

Authors

Tsun Holt Wong - University of Oxford
Peter Ireland - University of Oxford
Kevin Self - Rolls-Royce

Abstract

The trailing edge of the high pressure turbine blade and vane presents significant challenges to the turbine cooling engineer. The cooling design using cross corrugated slots allows for tuneable coolant flow through the slot, but results in poor film cooling performance, an effect that must be mitigated with exit shaping. A set of four cross corrugated slot geometries with optimised exit shaping has been investigated in a large scale model of the trailing edge slot. Pressure sensitive paint was used to measure adiabatic film cooling effectiveness at blowing ratios ranging from 0.6 to 1.4. The new optimised designs were able to improve upon previous designs, permitting levels of film effectiveness on the cutback surface up to the end of the lands that were significantly better than a plain rectangular slot at blowing ratios of 0.8 and below, while maintaining the pressure loss benefits of the cross corrugated slot and also increasing effectiveness next to the lands.