Optimization of geometric parameters of cylindrical film cooling hole with contoured craters to enhance film-cooling effectiveness

The present study aims at obtaining the optimum contoured crater for a cylindrical-based film cooling hole with maximum area-averaged cooling effectiveness via computational fluid dynamics and optimization method. The influences of 5 geometrical parameters, which depict completely the dimensions of the contoured crater, were discussed through performing the orthogonal experiment design and range analysis. The optimum designs at blowing ratios of 0.5 and 1.5 were obtained by using the range analysis and the genetic algorithm combined with back propagation neural network respectively. From the analysis of the results, it can be found that the latter optimization method outperformed with higher area-averaged cooling effectiveness at both blowing ratios. The area-averaged cooling effectiveness of the optimized cratered holes were improved by 17.21 % at blowing ratio of 0.5 and 101.96 % at blowing ratio of 1.5, respectively, compared to those of the reference geometry. The improvements on the film-cooling performance were explained in terms of the flow filed and the vortex structures.