A comprehensive heat transfer investigation for impingement/effusion cooling under crossflow conditions

Abstract

Impingement/effusion cooling is regarded as a highly efficient cooling structure and has been widely adopted in various energy-dependent scenarios. It often exhibits crossflow phenomena due to design or concurrent factors. However, quantifying the individual heat transfer contributions of each cooling structure in impingement/effusion cooling under crossflow conditions remains unclear. In this study, the pressure-sensitive paint and temperature-sensitive paint techniques were adopted to separately evaluate the performance of effusion and impingement cooling under crossflow conditions for a comprehensive heat transfer investigation. Different coolant flow rate (normalized as Rejet = 10,000 to 25,000) and crossflow flow rates (normalized as CMR = 0 to 0.3) were examined. In effusion cooling, cooling effectiveness generally decreased with higher Rejet but improved with increased CMR, except for Rejet = 10,000 and 15,000 with CMR ≥ 0.25, where excessive crossflow coolant negatively affected cooling effectiveness. When comparing cooling effectiveness at the same blowing ratio, higher Rejet with crossflow consistently outperformed, with the maximum improvement reaching 11.55 %. In impingement cooling, the Nusselt number (Nu) increased with Rejet due to enhanced impingement momentum. Crossflow had a detrimental effect at Rejet = 10,000 but showed improvements at Rejet = 15,000 to 25,000. With increasing Rejet, heat transfer performance became less sensitive to varying CMR. Compared to cases without crossflow, the Nu increments at CMR = 0.25 were -5.01 %, 4.03 %, 3.53 %, and 2.64 % for Rejet = 10,000 to 25,000, respectively. It was revealed that crossflow was influential on the impingement cooling, meanwhile, highly influential on the effusion cooling. This study intended to provide a more comprehensive understanding of impingement/effusion cooling and assistance in designing more efficient and tailored cooling strategies for high-performance energy systems.