The mechanism of emitter clogging analyzed by CFD–DEM simulation and PTV experiment
Small but complicated labyrinth channel emitters are easily clogged. In this study, computational fluid dynamics–discrete element method coupling approach was employed to investigate the mechanism of emitter clogging caused by particles in size of 65, 100, and 150 µm. Computational fluid dynamics used Navier–Stokes equation to analyze flow characteristics of continuous phase. Discrete element method used Newton’s laws of motion to measure single particle motion and group distribution of disperse phase. Particle tracking velocimetry was also utilized to follow the trajectories and velocity of single particle. Our results indicated that the smaller the particle size, the less the total force. Tiny sands were mainly influenced by drag forces. The amplitude between tooth tips was small. Particles moved basically in the main stream with fast velocity and short travel distance, thereby having good following performance. It took shorter time to reach micro-dynamic balance. Meanwhile, the amount of sediments in the labyrinth channel was less. Particles in size of 150 µm were mainly affected by inertial forces. They can easily enter vortex areas. Sands staying longer than 0.1 s in the labyrinth channel accounted for 37.9% of total number. Sand groups were mainly distributed at the inlet of labyrinth channel. The more sands trapped in vortex areas, the easier it was to precipitate and cause emitter clogging.
Keywords: Clogging, emitter, labyrinth channel, particle size, two-phase flow