Application of multi-scale methodology for transonic turbine blade tip cooling design

In recent research the cooling flow at transonic turbine tip is found to have several unique flow features such as strong interaction with the base flow, acceleration at divergent duct, strong shock-boundary layer interaction and weak correlation between the aerodynamic loss and the heat transfer. These flow features require the cooling design to be considered together with the tip geometry shaping. However due to the large disparity of the length scales between the cooling holes and the turbine blade, the combination of the cooling design and tip geometry shaping tends to be too computationally expensive to be employed. In this study the multi-scale method is implemented in a commercial solver to provide a fast and accurate solution for the turbine tip cooling design. The method uses source terms added on the coarse mesh to generate the solution that is rather close to the solution obtained with a well resolved mesh. The source terms are found to present not only the influence of mesh resolution but also the flow injection. The computed results have been validated against the experimental data and the fine mesh results. The good agreement shows a great potential for this multi-scale method to be used in cases with large length scale disparity.