Study on the Prediction Method for Multi-Row Film Cooling Superposition of the Turbine Outer Ring Considering Energy Conservation

The film superposition prediction model is a crucial tool in the preliminary design of hot-end components, enabling rapid prediction of film adiabatic wall temperatures and reducing computational costs. This paper establishes the relationship between the mainstream temperature correction coefficient and the air bleed ratio based on energy conservation principles at the boundary layer during film injection, developing a superposition model grounded in mainstream temperature corrections. The proposed model uses cooling effectiveness characteristics based on an equivalent blowing ratio to accurately predict the cooling effectiveness of multi-row hole layouts with different hole spacings. Experiments on adiabatic film cooling effectiveness were conducted with four different hole arrangements under various blowing ratios. The shortcomings of the traditional Sellers superposition method in predicting cooling effectiveness distribution are discussed by comparing it with the experimental results. Comparison results show that The Sellers method accumulates prediction errors as the number of hole rows increases, leading to an overestimation of cooling effectiveness compared to experimental results. Introducing a mainstream temperature correction factor could effectively solve the above problems. The prediction accuracy tends to be higher at lower blowing ratios and with a larger number of hole rows.Compared to the existing models in the literature, the proposed model has higher prediction accuracy under most conditions.