微通道冷却器内流动和传热特性的数值模拟

Numerical simulation of flow and heat transfer characteristics in microchannel cooler

为满足固体激光器用微通道冷却器的换热要求,根据冷却器结构分别建立了二维和三维物理模型,利用计算流体力学方法首先对比研究两者的流动特性,然后考察雷诺数和玻片生热量对微通道流动和传热特性的影响。结果表明:对于类似大平板间的矩形微通道层流流动区域,其流动及传热特性可直接采用二维简化模型进行模拟分析;对于重点关注的转捩区,采用三维模型模拟分析更好;当雷诺数增大到转捩点,流体的传热效果得到明显增强;随着雷诺数的增大,玻片生热量对通道内最低压力需求的影响逐渐减小;不同玻片生热量对微通道流动影响不可忽略,对努赛尔数和通道总压降基本无影响。

Computational fluid dynamics simulation was conducted in studying characteristics of fluid flow and heat transfer of microchannel cooler installed in a solid-state laser. Two-dimensional and three-dimensional physical models were developed,respectively,based on the cooler structure. Fluid flow within the microchannel was first investigated with the two models,then effects of Reynolds number and heat generation rate of crystal slice on fluid flow and heat transfer in the cooler were numerically examined. Results showed that the two-dimensional model was sufficient to describe the fluid flow and heat transfer behaviors in the laminar flow region in the rectangular microchannel between two parallel planes,and the three-dimensional model was more suitable for the transition region. When the Reynolds number was increased to the transition point,the effect of heat transfer from fluid flow was significantly enhanced. With the Reynolds number rising,the effect of the heat on minimum pressure required within the channel was gradually reduced. The change in the heat had an important influence on fluid flow,but little influence on Nusselt number and total pressure drop of the channel.