Abstract: The three-dimensional turbulent flow in a turbine cascade with blade film cooling is numerically investigated using a RNG turbulence model under different Reynolds numbers ranging from 4×105 to 6×105 and blowing ratios ranging from 0.5 to 3.0. The influence of the converging slot hole location at the blade suction surface (corresponding to the upstream of the throat, the cascade throat and the downstream of the throat) on the aerodynamic loss of the turbine cascade is investigated. Results show that the injection from the converging slot holes has effect only on the pressure coefficient distribution near the film cooling holes. The kinetic loss and total pressure loss induced by the injection from the film holes located at the upstream of the throat are lower than those induced by the other two locations, while the aerodynamic loss coefficients corresponding to the downstream of the throat location are the largest in most cases. Compared with cylindrical holes, the converging slot holes at the upstream of the throat exhibit both higher cooling effectiveness and lower aerodynamic loss coefficient.

Key words: converging slot hole, aerodynamic loss, film cooling, turbine cascade, suction surface