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对高宽比 c=3～ 1 5共 5个矩形通道的流动进行了水力实验 ,实验通道的当量直径 dh=1 .0～ 1 .2 mm,通道宽 b=0 .6～ 0 .8mm,流动雷诺数 Re=5 0～ 1 0 0 0 0。实验结果表明 ,大高宽比微小宽度矩形通道内的层流流动计算应考虑高宽比的影响 ,不宜采用当量圆管的公式。与普通圆管流动相比较 ,其层流 -紊流的过渡区变窄 ,不出现 f -Re图上阻力系数 f随 Re增大而增大的那一小段曲线 ,以及层流到紊流的最大临界雷诺数Rec 随高宽比 c而变 ,其最大值为 2 3 40
Hydraulic experiments were carried out on a total of 5 rectangular channels with aspect ratio c = 3 ~ 1 5. The equivalent channel diameter dh = 1.0 ~ 1.2 mm and channel width b = 0.6 ~ 0.8mm, Reynolds number Re = 5 0 ~ 1 0 0 0 0. The experimental results show that the calculation of the laminar flow in the small width rectangular channel with large aspect ratio should consider the effect of aspect ratio and the formula of equivalent circular tube should not be used. Compared with the ordinary tube flow, the transition zone of laminar-turbulent flow becomes narrower, and there is no small curve that the drag coefficient f increases as Re increases in f-Re diagram, and the curve of laminar flow to turbulent flow The maximum critical Reynolds number Rec varies with aspect ratio c, with a maximum of 2 3 40