Abstract: The film cooling characteristics of a converging slot hole on the blade suction surface of a turbine are numerically investigated using the RNG turbulence model under different turbine cascade inlet Reynolds numbers (ranging from 4×105 to 6×105 ) and blowing ratios (ranging from 0.5 to 3.0 ). The influence of the location of the converging slot hole at the blade suction surface (corresponding respectively to the upstream of the throat, the cascade throat and the downstream of the throat) on film cooling effectiveness is investigated. The results show that the converging slot hole cooling effectiveness in different locations all increases with the increase of the mainstream Reynolds number and coolant blowing ratio. Compared with the cylindrical hole, the converging slot hole cooling effectiveness is improved obviously and more uniform in lateral variation in all locations. Under the same condition, the cooling effectiveness of the converging slot hole at the upstream of the throat is nearly always higher than that in the other locations.

Key words: converging slot hole, film cooling, cooling effectiveness, suction surface, turbine blade