微通道内气体-近壁颗粒流动传热数值模拟研究

Numerical simulation of flow and heat transfer between gas and near-wall particle in a microchannel

数值模拟了微通道受限空间内气体-近壁颗粒流动与传热过程,所建模型考虑微尺度气体的可压缩与变物性特征,且在通道和颗粒壁面采用速度滑移和温度跳跃边界条件以考虑滑移区气体动量/能量非连续效应。在此基础上,计算分析了克努森数(K_(n))和颗粒偏移比对颗粒表面拖曳力系数(C_(D))以及传热努塞尔数(N_(u))的影响规律。研究结果表明:受气体稀薄效应影响,颗粒表面拖曳力系数呈减小趋势,换热过程也相应削弱;随颗粒与壁面距离减小,颗粒表面拖曳力系数相应减小,而颗粒与其周围气体的传热过程由于近壁效应呈增强趋势。

A numerical model, considering the compressibility and variable properties of gas, was established to simulate the gas-near wall particle flow and heat transfer characteristics in the microchannel. The velocity slip and temperature jump boundary conditions were implemented at the channel wall and gas-particle interface in the numerical modeling. The influences of Knudsen number and particle offset ratio on the drag coefficient(C_(D)) and Nusselt number were studied. The results show that the gas rarefaction effect decreases drag coefficient on particle surface and weakens heat transfer process between gas and micro particle. Moreover, the drag coefficient decreases with the decreasing of particle offset ratio, however, the heat transfer between gas and micro particle is enhanced due to the near-wall effect.