不同动态水压模式下迷宫流道内颗粒物运动特性研究

采用PTV技术,观测三角函数、三角、台阶、矩形波形动态水压模式下迷宫流道内颗粒物的运动情况,分析不同动态水压模式下迷宫流道内单个颗粒物运动轨迹、运动速度及流体流场,揭示动态水压抗堵塞机理。结果表明:相对于三角、台阶及矩形波形动态水压模式,三角函数波形动态水压模式下颗粒物滞留滞止区内的时间最短,颗粒物的沉积概率最小,水流对颗粒物的输移能力最大;三角函数波形动态水压模式下流道内产生的水流波动效应不断冲击流道滞止区内存在的低速漩涡,加剧了滞止区水流紊动,进入滞止区的颗粒物随水流不断运动,并对滞留甚至沉积在滞止区内的颗粒物发生强烈冲击,使得颗粒物离底悬浮,返回主流区,并迅速通过流道,增大了水流对颗粒物的输移能力,增强了流道的抗堵塞性能。

Particles Movement Characteristics in Labyrinth Channel under Different Dynamic Water Pressure Modes

The movements of tracer particles in a labyrinth channel were observed by using the PIV technique. The pressure was in dynamic modes with trigonometric function, triangular, step and rectangular waveforms. The trajectories, velocity of single particle as well as the overall flow field in the channel were analyzed to reveal the anti-clogging mechanism of dynamic water pressure. The results showed that when compared with constant water pressure, flow rates in the channel under trigonometric function, triangular, step and rectangular waveforms dynamic pressure modes were not decreased significantly. Therefore, effect of dynamic water pressure on water delivery capacity of drip irrigation system was not obvious. Among the different dynamic water pressure modes mentioned above, the trigonometric function type demonstrated the shortest particles residence time in the flow stagnation region. The deposition probability of particles was the lowest under this mode, indicating a better particles transport capacity in the channel. Fluctuation effect generated by the water under pressure of trigonometric function form produced effect on the low speed swirl in the stagnation region, and aggravated the turbulence of flow in this region. The turbulent flow was enhanced and the ability to carry the particles retained or even deposited in the stagnation zone was improved. As a result, the particles were suspended from the bottom and returned back to the main flow path. The transport capacity of the flow got strengthened, and the anti clogging performance of the channel was improved.Therefore, the trigonometric function waveform dynamic water pressure model can most effectively improve the anti clogging performance in the labyrinth channel.