区域供冷系统管路管件局部阻力系数综述

Review of coefficient of local resistance for pipe fittings in district cooling systems

局部阻力系数是为了简化描述、分析管道管件复杂流体力学现象提出的一个水力学参数,广泛应用于水力管道工程设计分析,其取值的准确性决定了管道水力学工程分析的准确程度。不同文献局部阻力系数取值差别较大,造成实际应用时管件压力损失的计算偏差,以及管道水力学计算的不同结论。本文回顾了几篇典型文献中管件局部阻力系数的取值,包括90°焊接弯头、90°三通、异径管、蝶阀等,其中,大管径90°弯头局部阻力系数接近0.2,90°三通局部阻力系数与分流比和面积比有关,异径管局部阻力系数与几何形状有关,蝶阀局部阻力系数与管径和开度有关。

The coefficient of local resistance is a hydraulic parameter proposed to simplify the description and analysis of complex hydrodynamic phenomena of pipe fittings,and widely used in the design and analysis of hydraulic pipeline engineering.The accuracy of its value determines the accuracy of pipeline hydraulic engineering analysis.In different references,the value of coefficient of local resistance varies greatly,leading to result deviations of pipe fitting pressure losses in practical application or different conclusions of pipeline hydraulic analysis.This paper reviews the value of coefficient of local resistance of pipe fittings in several typical literatures,including 90°welded elbow,90°tee,gradual contraction and enlargement and butterfly valve.Among which,the coefficient of local resistance of 90°elbow with large pipe diameter is close to 0.2,while the coefficient of local resistance is dependent on the flow ratio and area ratio for 90°tee,the geometry for gradual contraction and enlargement,and the pipe diameter and opening for butterfly valves,respectively.