灌水器微细流道水沙两相流分析和微PIV及抗堵实验研究

Two-phase flow analysis and experimental investigation of micro-PIV and anti-clogging for micro-channels of emitter

为可视化研究灌水器微细迷宫流道内含有未过滤掉的沙粒的实际流动状况,进而探索迷宫流道的堵塞机理,针对灌水器复杂且微细的迷宫流道结构(1mm左右),该文选取常用的矩形和锯齿形迷宫流道滴片结构,根据液固两相流理论,对其微细流道进行了水沙两相流计算流体力学数值模拟了CFD分析,得到了迷宫流道内流体的速度和流线分布及沙粒的运动轨迹和浓度的瞬时分布,分析认为流道内的低速区及涡旋区是造成堵塞的主要原因。并根据灌水器迷宫流道水沙两相流实验的需要,构建了微细流道中流动状态可视化测试的微粒子图像测速(Particle Image Velocimetry PIV)实验台,尝试应用微PIV测速技术对流道内两相流流场进行了测定,而且配合短周期堵塞实验验证了CFD计算的正确性。通过短周期堵塞实验分析得到了流道单元的最佳结构参数。

In order to visually study the real flow status of water mixed with sand escaped from filtering in the labyrinth channel of irrigation emitter, and to discuss some researches on the clogging mechanism of the labyrinth channel, aiming at complex and small labyrinth-channel emitters＇ structure （the size is about lmm）, the common used rectangular and zigzag channels were selected to perform the Computational Fluid Dynamics（CFD） analysis of liquid-solid flow according to the two-phase theory. The water flow velocity, path line, the particle tracks and concentration of sand in labyrinth channel were obtained. Through the anti-clogging analysis, the main reason of emitter clogging is low-velocity and stagnant areas existing in the labyrinth channel. Then based on flow visualization technology--micro-PIV （Particle Image Velocimetry）, the micro-PIV experimental bed was established, and the two-phase flow field in labyrinth channel was measured. Accuracy of CFD analysis results was tested with short period clogging experiment. Finally, through short period clogging experiment analysis, the optimal structural parameters of channels were obtained.