微通道内流体流动及换热特性的数值分析

采用Navier—Stokes方程与滑移边界条件联立的理论分析模型，对等壁温、等热流及无温度梯度工况下，气体在微通道中的流速分布、阻力系数变化趋势（Cf·Re）和传热特性（努塞尔数）进行了数值研究。结果表明：气体稀薄效应可显著减小管内的摩擦阻力和努塞尔数，增大气体流速；壁面的速度滑移和温度跳跃对微圆管内换热特性的影响相反，温度跳跃的影响更大；等热流加热与等壁温加热两种情况下，努塞尔数随克努森数的变化趋势明显不同。

Numerical Analysis of Flow and Heat Transfer Characteristics in Micro-channels

The characteristics of gas flow velocity,friction coefficient,and heat transfer(Nusselt number) in micro-channels under the conditions of equal heat flow,equal wall temperature,and no temperature grads were simulated by using the model of Navier-Stokes equations and slip velocity boundary conditions.The rarefaction effects can decrease the friction factor and the Nusselt number,and increase the mass flow rate;the velocity slip and temperature jump at the tube wall reversely affect the heat transfer of the micro-channels,and make the affection of temperature jump bigger.The Nusselt number decreases with the increasing of Knudsen number,but the decreasing effect is different under the conditions of equal heat flow and equal wall temperature.