扩缩型微通道内流体流动及传热特性数值分析

Numerical simulation of fluid flow and heat transfer characteristics in microchannels with expansion-constriction structure

微通道内扩缩结构的布置,有利于诱发二次涡流,提高传热性能。基于单侧矩形肋微通道(MC-OSRR),提出了单侧矩形肋和空腔(MC-RR.RC)、单侧矩形肋和扰流柱(MC-RR.RPF)两种组合结构微通道优化模型。在验证数值方法有效性的基础上,以去离子水为流动介质,运用Fluent软件模拟研究了不同体积流量、壁面温度、进口温度条件下扩缩型微通道的流动与传热特性。结果表明,空腔和扰流柱结构的引入,能进一步诱发二次流,促进流动混合,低体积流量下有利于增强单侧矩形肋微通道整体性能;相比空腔结构,布置于通道中央的扰流柱结构对主流体的扰动更为剧烈,高体积流量下无法在控制阻力增加幅度的基础上强化单侧矩形肋微通道传热。

The arrangement of the expansion-constriction structure in the microchannels is beneficial to induce the secondary flow and improve the heat transfer performance.On basis of the microchannel with one side of rectangular ribs(MC-OSRR),optimizational models of the microchannel with rectangular ribs and cavities(MC-RRC) and the microchannel with rectangular ribs and pin fin(MC-RRPF) were proposed. After verifying the validity of the numerical method, Fluent software was used to simulate the flow and heat transfer characteristics of deionized water in microchannels with expansion-constriction structures under different working conditions. The results show that the addition of cavities and pin fins can further induce the secondary flow and promote fluid mixing which is conducive to enhancing the comprehensive performance of MC-OSRR under low volume flow. Compared with cavities, pin fins arranged in the center of the microchannel has more severe disturbance to the main fluid which causes that the heat transfer performance of MC-OSRR can not be enhanced on the basis of controlling the increase of resistance amplitude under high volume flow.