等温气体管道压降计算的新公式(Ⅱ)

A novel equation of pipe pressure drop for isothermal gas flow(Ⅱ)

程惠亭-郝文斌之前给出的可压缩气体管道压降公式(简称A式)为显式,可以从管道起点参数出发计算压降,但如果已知管道终点参数去计算压降,就需要迭代求解,失去了显式公式的便捷性。为了能够从管道终点参数出发方便地计算管道压降,文中推导出了程惠亭-郝文斌计算可压缩气体压降的第二显式公式(简称B式)。采用与其A式推导时相同的条件,在建立微分方程时,不再使用先前的压力p沿管长l的函数关系,微分方程变得更简洁、求解过程更简单。所得B式和传统的等温公式相比,无需迭代求解且和A式有相同的精度。同时,所列举的实际计算例子表明:压降较大时,B式计算结果和韦默思公式、潘汉德公式计算结果非常接近,而与传统等温公式计算结果差异较大。

Based on the previous explicit equation(Equation A)of pipe pressure drop for compressible gas established by Huiting Cheng-Wenbin Hao,the pressure drop can be calculated from the parameters of pipeline starting point.However,if only the parameters of the pipeline end point are given,this formula needs to be solved iteratively,which lacks convenience.In order to tackle this problem,a second explicit equation(Equation B)of pipe pressure drop for compressible gas was derived and validated in this paper.Same conditions for the derivation of Equation A were adopted to derive Equation B,excepting the function relationship between pressure p and pipe length l,which made the differential equation more concise and more easily solved.Compared with the traditional isothermal equation,the reported Equation B does not involve the iterative calculation,and the result possesses the same precision with Equation A.The validation test suggestes that the calculation results of Equation B are very close to those of Waymerth equation and Panhandle equation at large pressure drop,while the results of traditional isothermal equation show a relatively large difference from those three results.