VISUALIZING PARTICLE MOVEMENT IN CYLINDRICAL DRIP IRRIGATION EMITTERS WITH DIGITAL PARTICLE IMAGE VELOCIMETRY

摘要

On the basis of precise analysis of the structure of the cylindrical emitter, we brought forward a testing method to visualize the particle movement with the model of the last stage unit segment of the flow path in the cylindrical emitter and digital particle image velocimetry (DPIV) technology. The movement characteristics of 10, 50 and 100 mu m particles were tested. The results showed that the method was reasonable and effective. The distribution characteristics of flow velocity and vortex in the flow path inside the emitter were not changed when the 50 and 100 mu m particles existed. However, the maximum velocities of particles in the centre area and the flow velocities of particles in the near-wall area decreased, and the following characteristics of particles in the mutation area of the flow path became weakened. The secondary flow whirlpool area still existed in the water flow in the cross section of the flow path, showing an obvious phase separation phenomenon. A flow-around cylinder structure could be set up in the low flow velocity area based on the Karman Vortex Street Principle in order to enhance its anti-clogging capability. Copyright (C) 2016 John Wiley & Sons, Ltd.