An Energy-Based Method for Predicting the Additive Effect of Multiple Film Cooling Rows

There have been numerous studies reporting film effectiveness for film rows in isolation, which have led to correlations that are used for preliminary design. Many applications require multiple film cooling rows. Although there is some published data which deal with the combined effect of multiple rows, in most design situations the additive effect is computed using correlations for single rows. The most widely used method is the Sellers superposition method. In many applications, the method gives accurate results. Although the method is to some extent physically based, energy is not conserved within the model, and in certain situations this limitation can be shown to lead to an underprediction of the film effectiveness. In this paper, a new energy-based method for predicting the additive effect of multiple film cooling rows is outlined. The physical basis and limitations of the model are discussed. Predictions conducted using the new method are compared with computational fluid dynamics (CFD) data and contrasted with the Sellers method. In situations where energy conservation is required to avoid underprediction of effectiveness the method is shown to be advantageous.