Evaluations of emitter clogging in drip irrigation by two-phase flow simulations and laboratory experiments

Emitter clogging will affect greatly the irrigation efficiency and the running cost of a drip irrigation system. if there is an effective method to predict the emitter clogging, the lost will be reduced to a minimum. A solid-liquid two-phase turbulent model describing the flow within drip emitters was studied. Then, the moving trace and depositing feature of suspending solids in emitter channels were obtained by computational fluid dynamics (CFD) based on the turbulent model established, which provided some visual and direct evidences for predicting the clogging performance of drip emitters. The three types of emitters with novel channel form, including eddy drip-arrows, pre-depositing drippers and round-flow drip-tapes, developed by us were used in this study. The simulation results showed that the solids moved along a helical path in the eddy drip-arrow, but no obvious deposition existed in its interior channel. In the pre-depositing dripper, some solids concentrated in the parts of "depositing pones". In the round-flow drip-tape, a small number of solids adhered to the out-edges of every channel corner, which was a potential factor for the occurrence of emitter clogging. To verify the predictions from the CFD simulations, series of "short-cycle" clogging tests for the three emitters were conducted in laboratory. The statistical data of discharge variation caused by emitter clogging were in good agreement with the two-phase flow CFD simulations. (C) 2008 Elsevier B.V. All rights reserved.