微型管内摩擦特性的实验研究

Experimental study on friction characteristics in microtube

以水、乙醇及四氯化碳作为工质,流过内径分别为0.168mm、0.399mm和0.799mm不锈钢管及内径分别为0.242mm、0.315mm和0.52mm石英玻璃管,测量其压降与流量,从而获得摩擦系数f与雷诺数Re的关系.实验结果表明,当Re小于1200～1800时,除内径为0.168mm的不锈钢管外,其他微管内的与经典层流理论值几乎一致;而对于内径为0.168mm,相对粗糙度为8%～10%的不锈钢管,当Re超过800时,其值比经典理论值高10%～15%;当Re超过1800时,所有微管的f值明显偏离经典层流理论值.

Water, ethanol and tetrachloromethane are used as working fluid and let it flow through stainless steel microtubes with inner diameters 0.168 mm, 0.399 mm, 0.799 mm and quartz glass microtubes with inner diameters 0.242 mm, 0.315 mm, and 0.520 mm. The relationship between friction factor and Reynolds number is obtained by measuring the pressure drop and the flow rate. The experimental results show that the friction factors in microtubes, except the stainless steel microtube with inner diameter 0.168 mm, are in rough agreement with the results by conventional theory when Re is less than 1200-1800. For microtube with inner diameter 0.168 mm and 8%-10% relative roughness, the value of friction factor is 10%-15% higher than that predicted by the classical theory. When Re is larger than 1800, the values of friction factors of all microtubes obviously deviate from the classical laminar theory values.