Influence of the Number of Circumferential Nozzles on the Flow and Heat Transfer Characteristics of Swirl Cooling

To study the effects of the number of circumferential nozzles in vortex chamber on the swirl cooling characteristics, two swirl cooling models were established, keeping the nozzle geometry and the total area of the nozzle inlets unchanged, respectively. At the same mass flow rate and nozzle aspect ratio, the effects of the number of circumferential nozzles on the swirling cooling characteristics were studied by numerical method, and the difference of swirling cooling performance between the two models were compared and analyzed. Results revealed that when the nozzle geometry is unchanged, the target average Nusselt number decreases with the number of nozzles, but the target Nusselt number distribution becomes more uniform. As the downstream air speed is more affected by the axial flow, the high Nusselt number region deflects downward. The number of air vortexes in vortex chamber decreases due to the increase in the number of nozzles, and the total pressure loss also decreases. When the total area of the nozzle inlets is unchanged, as the number of nozzles increases, the area of target high Nusselt number region and the average Nusselt number at first increase and then decrease, and become the largest when the number of nozzles is two. Because the downstream air velocity is less affected by the impact of axial flow, the target spanwise average Nusselt number has a small increase in the axial downstream, while the total pressure loss increases with the number of circumferential nozzles. © 2018, Editorial Office of Journal of Xi'an Jiaotong University. All right reserved.