灌水器内圆弧形流道的液固两相流场分析

Numerical Analysis on Liquid-solid Two-phase Flows in Arc-type Channel of the Emitter

针对迷宫流道灌水器结构细微复杂等特点,利用计算流体动力学方法对其流道内流场进行液固两相数值模拟。采用雷诺应力模型和壁面函数法模拟流体流动,采用离散相模型跟踪颗粒运动轨迹。研究表明,每个单元流道不同部位的流体流速相差较大,在圆弧顶部和右下侧均出现不同大小的漩涡,沿流动方向漩涡呈扩大趋势;小颗粒的跟随性比大颗粒的跟随性好,但更易受湍流脉动的影响,部分颗粒会在涡团中心处沉淀下来,导致流道堵塞,灌水器的堵塞实验结果验证了数值分析的正确性;相对颗粒直径而言,颗粒密度对其运动轨迹的影响要小得多。

Considering the structural intricacy of the drip irrigation emitter with labyrinth channel, a numerical simulation was carried out for the liquid-solid two-phase flows in arc-type channel by the CFD program Fluent. Reynolds Stress Model with wall function was adopted to calculate the liquid-phase flow,and Discrete Phase Model was chosen to trace trajectories of solid particles. The results obtained show that the differences of velocity in different parts are remarkable in each channel unit, and vortices are formed in the top and bottom right corners of the arc, which trend to become larger along the flow direction. The following behavior of small particles which are vulnerable to be affected by turbulent diffusion is better than that of large particles. The channel is easy to be clogging when a lot of particles deposit in these stagnant regions, which is verified by the clogging experiments of emitters. The particle trajectories are less affected by its density relative to its diameter.