Effect of Thermal Boundary Condition on Heat Dissipation due to Swirling Jet Impingement on a Heated Plate

This paper reports on experimental research conducted to investigate the convective heat transfer characteristics for jet impingement with and without swirl. A series of different nozzle to surface heights, ranging from 0.5D to 10D, and Reynolds numbers, ranging from 8000 to 20000, were examined to determine their influence on the heat transfer characteristics for varying degree of swirl. Two separate experimental setups, having different thermal boundary conditions, were used in order to determine the effect that the thermal boundary condition might have on the findings. The results obtained indicate that the Nusselt number distributions are largely similar for the two boundary conditions considered, with the method based on a uniform wall temperature with hot-film sensor measurements showing greater local variation and spatial resolution in the stagnation region. For the range of parameters tested, the stagnation region heat transfer is enhanced with the addition of swirl to the jet flow.