Heat Transfer in a Tall Coupled Impingement-Effusion Cooling System

Abstract The current study focuses on a coupled impingement-effusion cooling system, which combines impingement cooling on the backside of the cooled component and full coverage effusion cooling on the exposed surface. The goal of this study is to explore a wide range of geometrical parameters outside the ranges normally reported in the available literature. By determining impingement heat transfer, film cooling effectiveness, and film cooling heat transfer on the target wall, a simplified heat transfer model of the cooled component is developed to show the relative impact of each parameter on the overall cooling effectiveness. Temperature Sensitive Paint (TSP) for data acquisition allows for high-resolution local heat transfer and effectiveness results. Impingement arrays with local coolant extraction via effusion can produce higher overall heat transfer, as no significant cross-flow is present to deflect the impinging jets. Low jet-to-target-plate spacing produces the highest yet most non-uniform heat transfer distribution; at high spacing, the heat transfer rate is much less sensitive to impingement height. Arrays with high hole-to-hole spacing and high jet Reynolds number are more effective (per mass of coolant used) than tightly spaced holes at low jet Reynolds number. On the effusion side, staggered hole arrangements provide significantly higher film cooling effectiveness than their in-line counterparts, as the staggered arrangement minimizes jet interactions and promotes a more even lateral distribution of coolant. New methods of data comparison and normalization are offered to create an objective comparison of different configurations.