Heat Transfer Enhancement by Mitigating the Adverse Effects of Crossflow in a Multi-Jet Impingement Cooling System in Hexagonal Configuration by Coaxial Cylindrical Protrusion-Guide Vane Pairs

Abstract

Featured Application Advanced cooling in gas turbines and power electronics.Abstract A novel compound multi-jet impingement system for enhanced cooling of a flat surface by augmenting its area with cylindrical protrusions (CPs) equipped with coaxial guide vanes (CGVs) and reducing deflection of jets by crossflow has been developed for high-heat removal applications. The cooling performance of coaxial circular jets impinging on the top faces of CPs placed in hexagonal configuration on a flat plate is evaluated by three-dimensional (3D) computational fluid dynamics (CFD) simulations. Jets impinging on the top faces of the protrusions are directed to their lateral faces and then to the base plate by the CGVs around the protrusions, resulting in up to 62.8% improvement in heat transfer rate with a minor increase in pressure drop. Effects of protrusion height and diameter on the pressure drop and cooling performance are studied for jet Reynolds (Re number range of 5000-20,000. Due to both shortened jet impingement lengths as the height of protrusions is increased and directing the expended fluid away from the impinging jets by CGVs, adverse effects of jet-crossflow interactions on cooling performance and fluid pumping power are significantly reduced. Performance evaluation criterion (PEC) of the novel compound multi-jet impingement cooling system (CMJICS) can be as high as 1.52.