圆形管道90°汇流口局部能量损失

Local energy loss at right-angle junction of circular pipes

进行汇流管路特别是管路较短或汇流节点较多的管路系统设计时,正确确定管道汇流口水流局部能量损失具有重要意义.为此,根据水动力学基本原理,在分析90°汇流口独特水流特性及能量耗散机理的基础上,提出了局部能量损失系数的综合表达式,并应用试验资料对该综合表达式进行了验证.研究结果表明,正确分析管道汇流口水流的局部能量损失机理,必须考虑汇入断面上支流沿下游主流方向的动量输入和主支流间相互掺混引起的附加摩擦阻力的影响.

Rational determination of local energy loss of water flow at pipe junctions is of important significance in combining-flow pipeline design, especially for the short pipeline system with many junctions. From this point of view, a general analytic expression for the coefficient of local energy loss was presented based on the principle of hydrodynamics, together with experiments on particular flow characteristics and energy dissipation mechanism at right-angle junctions, and the expression was validated with the experimental data. Result of study indicates that the momentum input along with the branch flow toward the downstream and the additional friction induced by the mixing of main streams with branch flows should be considered for rational analysis of the local energy loss at junctions.