S型与U型管道阻力规律对比研究

A Comparison of Resistance Characteristics Between U-like and S-like Pipes

从几何学角度出发将S型和U型管道的阻力规律作了对比研究。通过实验研究提出S型管道阻力系数的经验公式,并与U型管道的阻力系数以及现行叠加计算值作了比较。实验结果表明,这种复合弯管的阻力系数,不能简单的用线性叠加原理计算,即将各几何组成部分的阻力系数叠加,应按其固有的阻力规律计算。另外,本文还分析比较了S型和U型管道的阻力变化规律,提出可用线性叠加原理计算的判据。

This paper makes a comparative study of resistance characteristics between S-like and U-like pipes from geometric aspects. In fact, the S-like and U-like pipes can be considered as a geometric symmetrical or asymmetrical compound bend pipe, respectively, which both consist of two elbows and a transition section. Hydraulic characteristics of the compound pipes are primarily dependent upon transition length between the two elbows as well as orientation of lower elbow. This paper develops empirical formulae of resistance coefficient of asymmetrical S-like pipe through experimental investigation, which are compared with resistance coefficient of symmetrical U-like pipe and linear superposition. Experimental results show that resistance coefficient of the compound bend pipe can not be simply calculated by linear superposition principle, that is, a sum of resistance coefficient from geometrical constituent parts, which should be calculated according to the intrinsic resistance law. In addition, variations in resistance of S-like and U-like pipes are analyzed and compared. And criteria suitable for linear superposition calculation are also presented.