Thermal performance of blade tip and casing coolant injection on a turbine blade with cavity and winglet-cavity tip.

Highlights • The blade tip and casing heat transfer characteristics were investigated with cavity and winglet cavity tips. • The cooling effects of the blade tip and casing coolant injection are investigated. • The blade tip and casing thermal performance are discussed under three cooling types. Abstract The heat transfer and film cooling effects of cavity tip and winglet-cavity tip have been numerically investigated with blade tip and casing coolant injection with a turbine cascade exit Ma number 0.96. The film-cooling effectiveness, heat transfer coefficient and net heat flux reduction ratio of blade tip and casing at relative tip clearance of 0.8% blade span are compared with blade tip cooling, casing purge cooling and the combination of these two cooling types. The validations and verifications of the numerical methods are performed by contrasting with the experimental results. The results show that the winglet-cavity tip alters the tip leakage flow and affects the heat transfer of blade tip compared to the cavity tip. For these two blade tip types, the blade tip cooling reduces the heat load of blade tip effectively, while it has little cooling effects on the casing. The casing purge cooling obtains high film-cooling effectiveness of the blade tip and the casing at the same time. However, it has no influence on the heat transfer of the pressure side near the tip region and the pressure-side rim. Adopting the blade tip and casing coolant injection simultaneously can further reduce the heat load and improve the film-cooling effectiveness of the blade tip and casing. [ABSTRACT FROM AUTHOR]