PVC三通管水流阻力与流动特征分析

Flow Resistance and Characteristics of PVC Tee Pipes

摘要:

对DN75×75和DN75×50两种PVC三通管进行了试验与数值模拟研究，结果表明主管—侧管流向的局部阻力系数ζ01和主管—直管流向的局部阻力系数ζ02随雷诺数的增大而减小，在雷诺数大于1.5×105之后基本趋于稳定；ζ01、ζ02与分流比呈二次抛物线关系，通过验证数值计算与试验结果基本吻合。在此基础上对5种常见型号的三通管进行了数值模拟，表明ζ01、ζ02随管径比的增大而减小，ζ01的变化幅度远大于ζ02的幅度，并给出了局部阻力系数随分流比变化的定量表达式；流动特征分析可知引起局部水头损失ζ01的主要原因是水流方向变化的损失和离心力造成的速度分布变化损失，而引起ζ02的主要原因是在较大分流比时水流的剪切和横向环流导致直管分岔处上侧的漩涡运动和流速梯度变化损失。

关键词:PVC三通管;阻力特性;流动特征;数值模拟

Abstract:

Two kinds of tee pipes DN75×75 and DN75×50 were discussed by test methods and numerical simulation. The results showed that local resistance coefficient of main branch to side branch ζ01 and main branch to straight branch ζ02 decreased with increasing Reynolds number and stabilized after the Reynolds number was greater than 1.5×105. The local resistance coefficient ζ01 and ζ02 was correlated with the flow ratio by second order parabolic equations. The numerical simulation results were in good with the experimental data. Through those variables other five kinds of tee pipes were simulated numerically. It showed that the local resistance coefficient ζ01 and ζ02 decreased with increasing diameter ratio, and the variable extent of ζ01 was greater than ζ02. Also the expression equation of local resistance coefficient variation with the flow ratio was given simultaneously. Flow characteristics analysis showed that the main reason caused the local resistance coefficient ζ01 due to the loss of direction changes and velocity distribution caused by centrifugal force, and changes ζ02 was due to the vortex motion and velocity gradient in the straight branch caused by water shearing and transverse circulation in the large flow ratio. 

Key words:PVC tee pipes;Resistance characteristics;Flow characteristics;Numerical simulation