Conjugate heat transfer analysis for composite cooling structure using a decoupled method

Composite cooling is a promising cooling technique in modern gas turbines. Quantifying the contributions of its internal and external cooling will help improve the cooling design and increase the cooling effectiveness. In this paper, a conjugate heat transfer (CHT) decoupled method is established firstly to decouple the complex interaction between internal and external cooling for a composite cooling structure. And then the rationality of the decoupled method is verified by comparing the flow and heat transfer characteristics of the decoupled model and the original composite cooling model. Using the decoupled model, the contributions of the internal and external cooling on overall cooling effectiveness are quantitatively evaluated, and the external cooling is found to encumber the overall cooling effectiveness when the film flow badly lifts off from the external surface. The detailed contributions of external cooling, impingement cooling, and film hole convective cooling on overall cooling effectiveness of the research model are additionally illustrated. Moreover, a prediction method is presented to estimate the overall cooling effectiveness based on the decoupled model, and a small prediction error is verified. The methods presented in this paper could be used in the preliminary and optimization stages of the hot end component design for gas turbines.