粗糙度与气体稀薄性对微尺度流动特性的影响

对氮气和氦气在粗糙微通道以及光滑微通道内流动进行了阻力特性实验研究。实验结果表明,即使在较小的相对粗糙度高度下,由于微通道中的粗糙度分布密集,会极大地增加流动阻力,这是导致文献中微通道流动阻力系数实验值相互偏差的主要原因之一;而对于滑移区的气体流动,气体稀薄性使流动阻力明显减小而导致流量增加。

ROUGHNESS AND RAREFACTION EFFECTS ON FLOW CHARACTERISTICS IN MICROCHANNELS

Experiments are conducted for nitrogen and helium gaseous flow through rough and smooth microchannels. The experimental results show that the surface roughness increases the flow resistance significantly even though the relative height is rather small. This is one of the major factors which causes the disagreements on the friction factor of microchannel flow in the literature; for the gaseous flow in the slip regime, an evident lower flow resistance is observed due to the gas rarefaction effect which causes the mass flow rate increase compared with the continuum flow.