微型管内摩擦特性的实验研究

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，从而获得摩擦系数厂与雷诺数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，所有微管的厂值明显偏离经典层流理论值．

Experimental study on friction characteristics in microtube

The teaching in course of physical education is the central part of teaching of physical education. What effects a class gets depend directly on the content and the form of course of physical education, whether which give rise to student's interest, mobilize the enthusiasm of their study , achieve the purpose of exercising their body and improve the equality of the teaching. However, the traditional, routine form of teaching has not already fitted completely to its demands. Therefore, I adopt tentatively the form of game in the teaching of physical education and gain good effects. I hope that it will be helpful for lots of teachers of physical education.