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一、前言在管路计算中,常遇到下列二种情况: (1)已知管径、管长和允许的压力损失,求流速; (2)已知管长、流速及允许的压力损失,求管径。由于流速或管径未知,不能计算雷诺准数Re,因此无法判断流动类型,以求得摩擦系数λ。这时,管路计算常采用试差法。试差法虽能求解,但由于计算繁杂,给工程计算带来很多不便。为避免求解隐函数,作者经分析计算并给出相应的Re-λRe~2及Re-λRe~(-1)关系图,采用直接图表法求解流速或管径。该图的原始数据系采用电子计算机求得,图表中
I. Introduction In the pipeline calculation, often encounter the following two situations: (1) known diameter, pipe length and allowed pressure loss, seeking flow rate; (2) known pipe length, flow rate and allowable pressure loss , Seeking diameter. Since the flow rate or tube diameter is unknown, the Reynolds number, Re, can not be calculated and hence the type of flow can not be judged in order to obtain the coefficient of friction, λ. At this time, pipeline calculation often use trial and error method. Although the trial-and-error method can solve, but due to the calculation complexity, to engineering calculation brings a lot of inconvenience. In order to avoid the solution of implicit function, the author calculated and given the corresponding Re-λRe ~ 2 and Re-λRe ~ (-1) graphs, and used direct graph method to solve the flow velocity or diameter. The original data of this figure is calculated by computer and chart