Enhanced heat transfer and thermal performance of a blade with tree-shaped film cooling channels

Modern film cooling is an essential method to protect the turbine blade from the hot gas, and the issue about how to improve the film cooling performance has attracted much attention. In this study, a tree-shaped film cooling structure is carried out to improve the overall effectiveness and better decrease the metal temperature of the blade at the same time. To validate the superiority of the proposed structure, a series of numerical simulation cases are conducted under a typical blowing ratio of M = 0.764. The first case is a film cooling channel with a single film hole which with a diameter of 5 mm and is inclined by α = 45° relative to the mainstream direction. The other three cases are tree-shaped structures with one level, two levels and three levels of bifurcations. For all cases, the same boundary conditions and turbulence model (Realizable k-ε) are adopted, and three-dimensional numerical simulations are used as well to test the thermal performance of the models. It is found from the computing results that the overall effectiveness of the tree-shaped structure is improved more than 50% compared to the case with a single film hole, and the results also demonstrate that the more levels of the structure the lower the metal temperatures. Therefore, it is indicated that this research will make a contribution to a higher performance gas turbine.