Prediction of transonic film cooling using the turbulent viscosity correction method

Two-equation turbulence models, such as the k-epsilon (k-epsilon) and shear stress transport (SST) models, have limited accuracy in calculating film cooling effectiveness. Previous studies have focused on modifying the turbulent Prandtl number from the perspective of thermal diffusion to improve the prediction accuracy of film cooling simulations. However, the flow accuracy of the jet flow is crucial for simulating film cooling. The calculated film cooling effectiveness differs from the experimental results due to deviations in the predicted amount of mixing. This study proposes corrections to the baseline k-omega model developed by Menter. The proposed method modifies the flow field with the mass species conservation equation in the mixing region while maintaining the advantages of the original model in the nonmixing region. The principle of the corrected model is explained through comparison and analysis with the SST model. The corrected model significantly improves the mixing effect of the two fluids. The main principle behind this is that the corrected model more accurately predicts turbulence intensity in the mixing zone of the two fluids. Furthermore, this paper experimentally validates the modified model for an array of film holes with Mach numbers of 0.4 and 1.4. The proposed model shows a 24% improvement in computational accuracy compared to the SST model.

Automated summary

The k-epsilon and SST models have limited accuracy in calculating film cooling effectiveness, so this study proposes a modified k-omega model that improves the mixing effect in the mixing zone of the two fluids by correcting the flow field with the mass species conservation equation.