Numerical simulation and optimisation of the inlet structure of dentiform emitters in drip-irrigation systems

Abstract

Emitter clogging adversely affects the performance of drip-irrigation systems. Many studies overlook the primary reason for emitter clogging by substances that precipitate within the emitter inlet. This study used computational fluid dynamics (CFD) to analyse the process of sedimentation in the inlet of emitters. Subsequently, the inlet structure was optimised based on the simulation results, production demand, and produced dripline. Anti-clogging physical tests were conducted in the laboratory and verified. Simulation results revealed that compared to the maximum discharge at the inlet of the domestic (CM) and Netafim (NF) emitters, that of the optimised (OS) emitter was increased by 60.0% and 13.2%, respectively; the maximum turbulent kinetic energy was increased by 88.9% and 13.3%, respectively; and the escape rate of solid particles in the dripline was increased by 3.2 and 5.9%, respectively. The results of an eighth-stage laboratory experiment with particle size ranges from 0.045 to 0.25 mm showed that the solid concentration was 1400 mg l⁻¹ for the CM-type emitter and 200 mg l⁻¹ for the OS-type emitter. However, the relative discharge of the OS-type emitter increased by 17.5%. At the end of the anti-clogging test, the relative discharge of the OS-type emitter was 0.12% more than that of the NF-type emitter. The water flowing through the OS-type emitter had a lower sediment content and higher relative discharge than of both comparison emitters. Therefore, optimising the emitter inlet can be an effective physical method for reducing the entry of solid particles into the emitter channel, which can greatly promote the sustainable development of drip irrigation.