Prediction of heat transfer characteristics for discrete hole film cooling for turbine blade applications

A two-dimensional (2-D) injection model is used with a 2-D low Reynold's number k-ε model boundary layer code. The three-dimensional effects of the discrete hole injection process is introduced in the 2-D prediction scheme through an 'entrainment fraction' (T). An established correlation between T and the injection parameters obtained in a previous paper is used to predict the film cooling effectiveness (η̄) and heat transfer coefficients for multirow injection, injection into a laminar boundary layer and finally injection on convex curved surfaces. Predictions of η̄ are in good agreement with experimental data for most of the cases tested. Predictions of Stanton numbers defined by St(0) and St(1) are good for low injection ratios (M) but as M increases the values are underpredicted. In spite of some shortcomings, in the authors' opinion, the present 2-D prediction scheme is one of the most comprehensive developed so far.