Effects of Holes Arrangement on the Superposition Characteristics of Film Cooling Effectiveness

The purpose of the current research is to test and analyze the applicability of the Sellers model in different arrangements and configurations of film cooling holes and then to modify the Sellers model to improve the accuracy of the superposition prediction. The film cooling effectiveness distributions at different blowing ratios are obtained using the infrared thermometry technology. The flat plate experiments are completed in a low-speed closed-loop wind tunnel facility. The mainstream Reynolds number based on the film hole diameter is 6300, and the blowing ratios range from 0.8 to 1.8. The superposition characteristics are described in three different cases: double rows of cylindrical holes in an inline arrangement, double rows of cylindrical holes in a staggered arrangement, and double rows of compound angle holes in an inline arrangement. The results indicate that the Sellers model cannot accurately predict the film cooling effectiveness in certain conditions, which is mainly attributed to the interaction between counter-rotating vortex pairs of the adjacent rows and the increasing momentum of mainstream near the wall surface. For all cases, the corresponding modified superposition prediction methods are given in this paper.