Single Hole Film Cooling on a Turbine-Blade Leading-Edge Model

The present study numerically investigates the effectiveness of film cooling on a turbine blade leading-edge model through a single-hole coolant exit. The model used in this study has the same dimensions as that of an experimental investigation done earlier by Ekkad et al [1]. The cylindrical model, a half cylinder and a flat after-body attached to it, well represents the leading edge of a turbine blade. The half-cylinder is 88.9 mm in diameter with a length of 364 mm. The flat after-body is attached to it to constitute the model of a turbine blade leading edge. The coolant hole is situated approximately at the center of the cylindrical model along the spanwise direction. The coolant hole makes an angle of 21.5 degrees to the true leading edge and 20 degrees to the spanwise direction. A multi-block grid is generated using GridGen, and the flow is simulated using the flow solver Fluent. The highly clustered structured C-grid is developed around the leading edge of the model with an initial Δy corresponding to a y+ value of 1 and a growth ratio of 1.1 till 10d from the surface. The outer unstructured domain imitates the wind-tunnel as used in the experimental study of Ekkad et al. [1], and the leading-edge model is placed at the center of the domain. Simulations are carried out for different blowing ratios M, ranging from 0.25 to 1.0, with the k-e realizable turbulence model and κ-ω SST model. The flow is assumed to have a free-stream turbulence intensity of 0.75%. Additionally, the enhanced wall function approach is used as the near-wall treatment in the computational model for the simulation with k-e realizable turbulence model. Results obtained indicate an increased film-effectiveness for low blowing ratio in the far downstream region. Also, in the vicinity of coolant jet exit, it is observed that increase in blowing ratio increases the film cooling effectiveness.© 2007 ASME