Abstract: The flow characteristics of deionized water in stainless steel microtubes were experimentally investigated in this study.The influences of relative surface roughness and inner diameter of tube on pressure drop were discussed.The inner diameters of microtubes were 543.3,654.4 and 737.2 μm,with the relative surface roughness 0.31%,0.16% and 0.1%,respectively.In experiments,long tube and short tube were used and compared to eliminate the effect of inlet and outlet.The relationships between pressure drop and Re with different diameters,between friction factor f and Re,and between Poiseuille number and Re were obtained.The results show that the variation of tube diameter affects the pressure gradient.With the decrease of tube diameter,the pressure gradient increases quickly.Large relative surface roughness(ε=0.31%,d=543.3 μm)results in higher friction factor and earlier transition point(Re_c≈1500),while smaller relative surface roughness(ε=0.16%,d=650 μm)has little effect on the laminar flow characteristics.

Key words: microtube, deionized water, roughness, friction factor

摘要： 实验研究了去离子水流过不锈钢微圆管时的阻力特性,微圆管直径为543.3、654.4、737.2 μm,对应的壁面相对粗糙度分别为0.31%、0.16%、0.1%。实验中,采用长短管比较法消除实验段进、出口的局部阻力影响,通过测量得到了不同管径的压力梯度随Re的变化关系,及摩擦阻力系数f和Poiseuille数随Re的变化关系。结果表明,压力梯度随管径减小快速增加;管径较小时(d=543.3 μm)壁面相对粗糙度ε=0.31%时影响管内流动,使得摩擦阻力系数及Poiseuille数增加,转捩点提前(Re_c≈1500),当管径大于650 μm时,较小的壁面相对粗糙度不影响管内层流流动。

关键词: 微圆管, 去离子水, 粗糙度, 摩擦阻力系数