FRICTIONAL FLOW CHARACTERISTICS OF WATER FLOWING THROUGH RECTANGULAR MICROCHANNELS
FRICTIONAL FLOW CHARACTERISTICS OF WATER FLOWING THROUGH RECTANGULAR MICROCHANNELS
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DOI：
10.1080/08916159408946484
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发表时间：
1994-10-01
影响因子：
3.5
通讯作者：
WANG, BX
中科院分区：
文献类型：
--
作者：
PENG, XF;PETERSON, GP;WANG, BX
实验研究了水力直径为0.133-0.367 mm、高宽比为0.333-1的矩形微通道内水的流动特性。实验结果表明，层流转捩发生在雷诺数为200-700之间。层流过渡的临界Re受到水力直径的强烈影响，随着微通道中相应的减小而减小。此外，在低得多的Re下，转捩范围的大小减小，并且也发生充分发展的湍流。层流和湍流的摩擦行为被发现偏离经典的热流体的相关性。发现摩擦系数f在层流条件下与Re-1.98成比例而不是Re，在紊流条件下与Re-1.72成比例。几何参数，水力直径，和H/W被认为是最重要的参数，并有一个关键的流动影响。通常，增大H/W比会增大摩擦系数。对于给定的H/W，微通道水力半径的减小显著地降低了摩擦因子。存在一个特殊的H/W比范围（约0.5 mm），在该范围内，实验数据低于从经典相关性获得的预测。通道尺寸的继续减小增大了Re-cri处f（l，exp）和f（l，theo）之间的差，并且f（l，exp）的量在H/W = 0.5附近的区域内变小，而在H/W = 0.5之外的区域内变大。
Experiments were conducted to investigate the flow characteristics of water flowing through rectangular microchannels having hydraulic diameters of 0.133-0.367 mm and H/W ratios of 0.333-1. Experimental results indicated that the laminar flow transition occurred al Reynolds numbers of 200-700. This critical Re for the laminar transition was strongly affected by the hydraulic diameter, decreasing with corresponding decreases in the microchannel. In addition, the size of the transition range was diminished and fully developed turbulent flow also occurred at much lower Re. The friction behavior of both the laminar and turbulent flow was found to depart from the classical thermofluid correlations. The friction factor, f, was found to be proportional to Re--1.98 rather than Re for the laminar condition, and proportional to Re--1.72 for turbulent flow. The geometric parameters, hydraulic diameter, and H/W were found to be the most important parameters and had a critical effect on the flow. Generally, increasing the ratio H/W increases the friction factor. The reduction of the microchannel hydraulic radius decreases the friction factor significantly for a given H/W. There exists a special range of ratio H/W (approximately 0.5 mm) at which the experimental data are lower than the predictions obtained from classical correlations. Continued reduction of channel size increases the difference between f(l,exp) and f(l,theo) at Re-cri, and the quantity of f(l,exp) Becomes smaller within the region adjacent to H/W = 0.5, and larger when H/W is out of this region.