通断微通道流动特性的数值模拟研究

微通道换热器以其良好换热能力已被广泛地应用于当前的实验研究中,通过数值模拟的方法对通断微通道内的流动特性进行了研究。重点分析了通道结构对微通道内速度分布、压力分布的影响。结果显示,通断通道的整体压降比连续通道增加了17%,当微通道内的雷诺数>1 500时,微通道内单相流动达到了旺盛湍流,宽高比对压降的影响消失。通断通道结构下的流动转捩雷诺数600～800之间,比常规尺度下的转捩雷诺数低得多(2 300左右)。通过通道数对流动性能的研究发现,增加通道数,有利于降低整体压降并增加流动稳定性。

Numerical simulation of flow characteristics of on-off microchannel

Microchannel heat exchangers are widely applied in the current research and experiments for their excellent heat transfer capacity.In this paper,the flow characteristics in the on-off microchannel were studied by numerical simulation.The influences of channel structure on velocity and pressure distribution in microchannel were analyzed.The results show that the overall pressure drop of the on-off channel is 17%higher than that of the continuous channel.When the Reynolds number in the microchannel is more than 1500,the single-phase flow in the microchannel reaches strong turbulence.The flow transition Reynolds number under the micro-channel structure is between 600 and 800,which is much lower than that under the conventional scale(about 2300).It is found that increasing the number of channels is beneficial to decrease the overall pressure drop and increase the flow stability.