微喷灌稳流器流道水沙两相流数值模拟

Numerical simulation of water-sand phase flow in regulator channel of micro-sprinkler irrigation system

针对微喷灌压力补偿灌水器流量调节不稳定、流态指数不达标的难题,设计一种结构紧凑且适用于微喷灌大流量的稳流流道结构,并通过数值模拟分析流道结构的消能机理和抗堵塞性能.应用ANSYS FLUENT软件,采取RNG k-ε模型获得消能流道内的压力场、速度场、涡量场以及颗粒物沉积分布情况.结果显示,流场结构的自冲洗性能优良,流道内局部沙粒浓度最高不超过8.5%,300 kPa工作压力下的抗堵塞性能最好.流道内部的涡量是反映含沙量的重要参数,涡量值与沙粒浓度成反比.W型圆弧流道及变径流道结构可以增加流体的紊动程度,有效地消能稳流,使灌水器在大流量下保证稳定良好的水力性能.研究结论为压力补偿灌水器的内部流道结构的优化提供了一定的参考.

In order to improve the flow regulation properties of pressure-compensation emitters in the micro-sprinkler irrigation,a compact flow channel structure of the regulator was designed,which is suitable for micro-sprinkler irrigation with larger flow rate.The energy dissipation mechanism and anti-clogging performance of the channel structure were analyzed through numerical simulation.Based on the ANSYS FLUENT software,the pressure contour,velocity contour,vorticity contour and particle deposition distribution in the energy dissipation channel were obtained by using the RNG k-εmodel.The results show that the flow field structure has good self-cleaning performance,the maximum sand concentration in the channel is less than 8.5%,and the anti-clogging performance will be the best under 300 kPa operating pressure.The vorticity in the flow field is an important parameter to reflect the sediment concentration,which is inversely proportional to the sand concentration.The W-shaped and variable diameter channel structure can increase the turbulence degree of the fluid,dissipate energy and keep the flow rate constant effectively,to ensure the a good hydraulic performance of the emitter under the larger flow rate,which provides a reference for the optimization of the internal channel structure of pressure compensation emitters.