Research On Hydraulic Performance Of Ladder-shaped Perforated Drip Irrigation Emitters

Objective: Drip irrigation has the functions of saving water and fertilizer,increasing output and increasing efficiency.It is one of the main water-saving irrigation methods in general at present,and drip irrigation sprinkler is the core equipment of drip irrigation.The implementation of high-efficiency irrigation and the development of advanced water-saving equipment play a major role in alleviating water shortages,improving agricultural science and technology content and water utilization efficiency,and increasing agricultural output.Therefore,in order to adhere to sustainable development,prevent technological blockade,and optimize traditional irrigation methods,it is still necessary to develop more new drip irrigation equipment with independent intellectual property rights and more targeted at different industries or crops.This research is based on the biomimetic theory,based on the ladder-like perforated plate structure in the xylem duct of plants,after professional transformation,a ladder-like perforated channel and a drip irrigation emitter based on the channel are proposed.The trapezoidal perforated drip irrigation emitter has the characteristics of simple structure and excellent hydraulic performance.However,the relationship between the structural parameters and hydraulic performance of the emitters and its energy dissipation mechanism have not been explored,and the hydraulic performance of the trapezoidal perforated drip irrigation emitter can still be further improved.Methods: This research carried out an experiment and two sets of numerical simulations.In the hydraulic performance test,16 sets of structural schemes were designed for the four trapezoidal perforated drip irrigation emitters extracted by the orthogonal experiment design method,and the hydraulic performance test platform of the drip irrigation emitter was used to measure the discharge flow of each test program under different pressures.Two sets of numerical simulations were carried out at the same time.Numerical simulation one studied the flow rate,flow field,flow rate ratio and flow state index of different structural schemes under different pressures.The second numerical simulation studies the flow field distribution in the perforated channel under different pressures,the geometric characteristics of the vortex area,the vortex intensity and the pressure distribution,and analyzes the movement of the sand particles of different sizes in the emitter.This study uses a combination of physical experiment and numerical simulation to determine the hydraulic performance,flow field,energy dissipation mechanism and the influence of different structural parameters on the hydraulic performance of the perforated drip irrigation emitters.And explore the simulation method and mathematical model applicable to the perforated drip irrigation emitters.Results :(1)The trapezoidal perforated drip irrigation emitter has excellent hydraulic performance.The output flow range of 16 groups of structural schemes is 2-8L/h.The hydraulic performance in the high pressure area is better than that in the low pressure area,and the flow pattern index is 0.4781-0.5146.The coefficient is 0.2732-0.5326.The influence on flow index: perforation width > perforated plate inclination > distance between two perforations far side > runner cavity length.The regression equation of multiple fitting is reliable and the fit is good.(2)The relative error between the numerical simulation of the trapezoidal perforated drip irrigation emitter and the measured value is 1.381%-2.439%,and the correlation coefficients are all higher than 0.998.The flow index of the numerical simulation trapezoidal perforated drip irrigation emitter is 0.4665-0.5266.(3)The shape of the vortex zone under different pressures is stable and can exist stably.The vortex zone can continuously wash and clean the side wall of the flow channel and slow down the accumulation of particles in the perforated flow channel;between the flow layers of different velocities in the vortex zone,between the vortex zone and the main flow zone,and between the vortex zone and the side wall of the flow channel The friction will consume energy.Conclusion: The hydraulic performance of perforated drip irrigation emitters is affected by the structural parameters.The main energy dissipation mechanism of perforated drip irrigation emitters is to consume energy through the hedging between the two water streams formed by the perforated plate.The water flow ratio can be optimized to improve the emitters’ hydraulic performance.Utilizing the vortex area in the emitters can improve the anti-clogging and hydraulic performance of the emitters.Considering the energy dissipation mechanism of the trapezoidal perforated emitter and the influence of structural parameters on the hydraulic performance,it is recommended to optimize the trapezoidal perforation by optimizing the entrance size and form of the upper perforation near the side wall of the flow channel,as well as the perforation width and the angle of the perforated plate.The hydraulic performance of the Ladder-shaped perforated drip irrigation emitters.