摇臂式喷头内流道流动分析与数值模拟

应用CFD通用软件Fluent模拟了PY140型摇臂式喷头的内流道在安装两种常用稳流器和不安装稳流器情况下的三维黏性流场，分析了三种稳流器情况下喷头流量、内流道静压力分布以及出口断面平均湍动能随进口工作压力的变化规律，并进行了试验验证。研究结果表明不同进口工作压力下喷头流量的计算值要高于实测值约11％，但两者的变化趋势非常一致。喷头安装稳流器有助于消除内流道中的涡流和横向流，降低喷头出口湍动能值，但在一定程度会增加内流道阻力损失，影响喷头的过流能力。此外，常用的 90°出口扩散角的圆锥形喷嘴容易在喷嘴出口附近产生逆流。数值模拟和试验表明，减少喷嘴出口扩散角可改善喷嘴出口流态，提高喷头流量。

Numerical simulation of internal flow field in impact sprinkler

The internal flow fields in impact sprinkler with two kinds of flow straightener or without straightener were simulated by using the CFD software FLUENT. The differences of flow rate, static pressure distribution along the flow passage and the variation of average turbulent kinetic energy at nozzle outlet following the change of inlet flow pressure for different conditions of flow straightener were predicted and verified by experiments. The results show that the flow rates obtained by numerical simulation are higher than those measured from experiments by 11%. The straightener are helpful in eliminating the vortex and transverse flow and reducing the turbulent kinetic energy at nozzle outlet, but the resistance of flow passage will be increased and the flow rate will be reduced. Besides, the simulation and experiment also reveal that reverse flow always happened to the outlet of conventional nozzle with 90° diffusion angle. The reduction of diffusion angle at nozzle outlet can effectively improve the flow pattern at nozzle outlet and increase the flow rate.