Application of Computational Fluid Dynamics to Design High Performance Drip Irrigation Emitters

Abstract

xH k Q ⋅ = , where Q is the flow rate (l/hr), k is an emitter constant, H is the pressure head (kPa), and x is the emitter flow rate exponent. The constants k and x are always used to evaluate emitter’s hydraulic performance. Therefore, the structure can be optimized according to the evaluation parameters till reaching a satisfied result. On the other hand, emitter clogging has been considered one of the most annoying problems inhibiting the popularization of drip irrigation; it can be caused by physical, chemical or biological contaminants [4-5]. Regardless of which kind of the clogging, it can be ascribed to the deposition of particles with different diameters (sand, indissolvable carbonate, bacteria etc.) in emitters. Usually, we conclude the drip irrigation whether is clogged or not based on the flow rate at the same pressure head. We are not sure why and how emitter’s discharge is reduced? CFD can simulate the motion and trajectories of particles and visualize the single particle’s stagnation position by using stochastic trajectory model. In addition, by means of Eulerian-Eulerian model, potential deposition regions of plenty of solid particles can be obtained, which can be used to explain the clogging mechanism of emitters [6]. These simulation results are good criterions for structural optimization of emitters. CFD is an effective technique to discover the flow behavior of the fluid in labyrinth channels which is important for the microcharacteristics of the emitter. The researchers and manufacturers can design serials of high-performance emitters by using CFD.