engleski

Numerical simulation of the effect of backward hole configuration on improving film cooling performance

Increasing temperature at the gas turbine inlet has far exceeded the melting point of the metal materials. In recent years, the film cooling technology has protected gas turbine blades from the erosion of high-temperature gases. As is well- known, an optimal injection angle of film cooling holes can provide a full coverage to the cooling protection for blade walls. Previous studies mainly focuses on the traditional (forward) injection angle, i.e., the jet flow is consistent with flow direction of the mainstream, but research about a backward injection of the jet flow is insufficient. In this paper, all numerical simulations are used to analyze flow characteristics and film cooling performance of the backward injection hole in a simplified channel, and physical mechanism of improved cooling performance from the backward injection hole is revealed by a comparison with simulated results based on a forward injection hole. The results show that the backward injection hole can weaken the strength of the kidney vortices, and the spanwise cooling distribution of the jet flow on wall surface is wider than the forward injection. Moreover, at low blowing ratios, film cooling performance for the backward hole is worse than the forward hole, whereas the backward hole at high blowing ratios has better film cooling performance than the forward one. At the blowing ratio of 1.5, the overall average film cooling effectiveness for the backward hole increases by 619% compared to for the forward hole.

Film cooling ; computational fluid dynamics ; injection angle ; backward injection ; gas turbine

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