Experimental study of flow characteristics in microchannels with different surface roughness

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Institute of Engineering Thermophysics, Chinese Acad. of Sci., Beijing 100080, China ^{[1
]}

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Shanghai Ligong Daxue Xuebao | 2008年 / 1卷 / 55-58期

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摘要：

An experimental investigation has been performed on flow characteristics and pressure drop of water, alcohol and hexane in 3 different roughness rectangle stainless steel microchannels. It is found that the hagen-poiseuille number is higher than those predicted by the classical theory and the hagen-poiseuille number is unconstant but slowly increases with the Reynolds number and increases with the surface roughness in laminar area. For the small relative roughness(k/Dh less than or equal 3%), the critical Re number is between 1685 and 1760 which shows that the laminar-turbulent transition in microchannels will not appear earlier than that the classical theory expects. But for the large relative roughness(k/Dh= 3.15%), the critical Re number is about 1500 which shows that laminar-turbulent transition in microchannels does occur in advance. The experimental results also show that for the small relative roughness (k/Dh less than or equal 3%) and for Reynolds number smaller than 1600, the friction fractor maintains almost the same value, but for the large relative roughness (k /Dh=3.15%), and for Reynolds number between 200-2800, the friction factor becomes higher. The friction factor is about 30%-40% higher than the traditional predicted value. The liquid polarity has little effect on friction factor.

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