EXPERIMENTAL INVESTIGATION OF DISCHARGE COEFFICIENTS OF DOUBLE WALL COOLING SYSTEMS

Double wall cooling technology is considered to be the most promising solution for next-generation gas turbine blade cooling, featuring enhanced cooling performance, reduced coolant air consumption, and a more uniform distribution of thermal stress. However, interactions in a double wall cooling system exist among the flow disturbance elements such as impinging jet, film cooling, and pin fins. Meanwhile, the arrangement and geometric parameters of the impingement/film in the double wall are different from those of traditional cooling. As a result, the flow resistance characteristics of each component are not independent of each other. Therefore, to accurately predict coolant air consumption within a double wall cooling system, this study focuses on the influence of geometric and flow parameters on the flow resistance of double wall effusion cooling system through experimental methods. The findings showed that the hole spacing, film hole inclination angle, and the number of pin fins have a significant impact on the discharge coefficient in double wall cooling. Furthermore, the internal crossflow severely affects the flow through the film cooling holes, resulting in a noticeable decrease in the overall discharge coefficient of the double wall system.