滴灌灌水器侧壁斜度和外形曲率对其性能的影响

The Influence of Side Wall Slope and Exterior Curvature of Drip Irrigation Emitter on Its Performance

基于计算流体动力学(CFD)研究了内镶式灌水器流道的流场,分析了流道侧壁斜度对其水力性能的影响,发现灌水器具有2°~4°的流道侧壁斜度能够减小其流态指数。采用离散相模型(DPM),对比了颗粒在圆弧形灌水器和平板型灌水器流道内浓度分布,并从流道截面流场速度分布、中面流场垂直速度分量分布和颗粒运动轨迹3个方面分析了颗粒浓度分布差异的原因,认为圆弧形灌水器流道中颗粒运动复杂,更易造成堵塞,其外形设计劣于平板型灌水器。采用四板式可视化平面模型装置,通过水力性能实验测量了不同工作压力下出口的流量,获得的实验结果和模拟结果相差仅有5%,并通过可视化实验获得了流场局部矢量图,验证了模拟所得灌水器流场分布的结果。

The anti-clogging performance of the drip irrigation emitter is an important index to measure the quality of the drip irrigation system,which is directly related to its flow field characteristics. The influence of the slanting angle of the side wall on its flow field was studied by the method of computational fluid dynamics（ CFD）. Through the discrete phase model,the effect of the curvature of the top and bottom surfaces of the channel on its anti-clogging performance was also studied by the solid-liquid coupling method. The flow rates under different pressures and the transient flow field of the transparent device with the shape characteristics of the drip irrigation emitter channel were gained through the hydraulic performance and visualization experiment respectively. The result shows that the numerical simulation values are highly consistent with the test results,the error of the maximum velocity in the flow field is only about 5.2% to 10%,and the difference of the hydraulic performance curves obtained by experiment and simulation is only 2% to 5%. The study indicates that the flow rate increases with the increase of the slanting angle of the side wall,and the flow index of the drip irrigation emitter can be effectively decreased when the side wall of channel has a 2° ~ 4°slanting angle. The drip irrigation emitter which possesses flat top and bottom surfaces has a better anti-clogging performance,comparing to the one with curved top and bottom surfaces. Because the particles in the flat type drip irrigation emitter are not easily involved into the vortexes in the channel,they can leave faster than those in the curved one.