Study on the flow and heat transfer characteristics of a double-wall structure with multiple-jet impingement cooling under rotating conditions

This study employs Time-Resolved Particle Image Velocimetry (TR-PIV) to investigate the effects of rotation on the flow structure and heat transfer in a double-wall system under target surface heating conditions. The dimensionless jet-to-target spacing is 3, the jet Reynolds number is 4500, the jet rotation number ranges from 0 to 0.09, and the maximum buoyancy number is 0.2. By corroborating validated simulation results with experimental findings, the study provides a deeper explanation of the flow and heat transfer mechanisms. The flow characteristics are studied by the mean velocity, Reynolds stress, and turbulent kinetic energy. The results indicate that the Coriolis force, buoyancy force, centrifugal force, and pressure gradient cause jet deflection. When the rotation direction varies, the jet deflects towards the Coriolis force direction, and the degree of deflection increases with the increase of the rotation number. Rotationally induced buoyancy affects the jet mass flow rate distribution, increasing the mass flow rate at a high rotational radius and decreasing it at a low rotational radius. Rotation weakens the heat transfer efficiency of the target surface. Under the same rotation number, the average Nusselt number on the suction surface of the target surface decreases by 8.92 % compared to the stationary case, while on the pressure surface, it decreases by up to 21.8 %, indicating poorer heat transfer performance. Analysis of Ω-vortex identification reveals that this phenomenon is related to the differing vortex structures of the jet under varying rotation directions.