摘要
用理论与实验说明:尼古拉兹用实验两次修改了普朗特混合长度公式,一次是递增论的混合长度,一次是分区论的混合长度,但两次修改都存在错误;由于实验装置的管径是固定的,测得的数据不具普遍性。故得出结论:由于实验装置的管径是固定的、只测时均速度而不测脉动速度和根据拟定的错误公式进行的实验,在混合长度理论中,尼古拉兹的实验结果都是不正确的。
Theory and experiment have illustrated that the Prandtl mixing length formula having been revised twice by Nikuradse experiment is wrong in which one is in constant increasing theory,another in subregion theory of mixing length;and owing to the pipe diameter of experiment equipment being fixed the data surveyed have no representation.Hence it may been obtained a conclusion that because of the pipe diameter of experiment being fixed,only determining the temporal mean velocity not fluctuation and the experiment being made on the basis of wrong formula,the results of Nikuradse experiment are incorrect in the mixing length theory of Prandtl.
出处
《中国矿山工程》
2016年第5期81-84,共4页
China Mine Engineering
关键词
雷诺应力
湍流总切应力
时均速度
脉动速度
拥挤效应
Reynolds stress
turbulent total shearing stress
temporal mean velocity
fluctuation velocity
crowding effect
