直角Z形组合双弯管流动特性的研究

多片焊接弯管是火、核电厂循环供水管路系统中应用最多的形变件，最常见的安装形式是两个弯管的0°组合。当弯管间距较小时，会出现上、下游弯管管内流动的相互影响。本研究采用二维激光多普勒测速仪和五孔探针测得4片90°弯管Z形组合在不同弯管间距下水流特征断面上的三维流场、压力分布以及紊动特性的沿程变化等。并以此探求双弯管局部阻力相邻影响的机理。限于篇幅，本文仅对测得的水平直径轴向流速分布以及特征断面上二次流形态进行了分析，指出双弯管间相邻影响系数的变化规律受弯管二次流动、涡流区、弯管进出口流速核大小以及上、下游弯管间流速分布调整程度等4个方面的制约；弯管间过渡直管段的长短是改变局部阻力相邻影响的关键因素。

Hydraulic characteristics of Z-type pipe combination with two similar rectangular bends

The Z-type pipe combination with two similar rectangular bends is always used in circulating cooling water system of thermal/nuclear power stations.Interaction between two bends will occur when the installation space is relatively small.The Laser Doppler anemometer and spherical probe with five holes are used to measure the flow velocity,pressure and turbulence intensity distributions in pipes to investigate the interactions between two bends with various distances.The results show that the interaction resulting in the variation of hydraulic resistance of bends is affected by the secondary flow in the bends,eddy due to separation,flow conditions of inlet and outlet as well as the distance between two bends.Among them,the distance between two bends is the major factor influencing the local hydraulic resistance of bends.