Study On Anti-clogging Performance Of Drip Irrigation Emitters Based On Jet Tee

Pulse drip irrigation is an irrigation technology with high uniformity and strong anti-clogging ability.It is an effective way to improve the anti-clogging ability and irrigation uniformity of high and low pressure of surface and underground dripirrigation.The existing pulsed drip irrigation system is a pulsed drip pipe system formed by fluctuating water pressure through a single chip computer,frequency converter and programmer controller,but it is relatively high cost,reliability and durability are difficult to guarantee,and its use and maintenance are complex,which limits.It use and application in pulsed drip irrigation technology.In this study,a capillary jet tee designed by predecessors based on the principle of jet wall attachment was used to study the pulse wave generated by jet tee,and compared with four kinds of high-frequency pulse wave and four kinds of low-frequency pulse wave on particle deposition concentration and particle trajectory.The anti-clogging test of jet tee at a constant pressure condition was carried out under short and long period conditions.The anti-clogging mechanism and application scope of jet tee were analyzed.The main research contents and conclusions are as follows:(1)Through the hydraulic test of capillary jet tee,the pulse flow waveform was studied.It was found that the pulse wave generated by the tee is in good agreement with the sinusoidal wave form,which indicates that the sinusoidal wave can be used as th e pulse wave of the jet tee to carry out the simulation test,and verification tests on hydraulic performance of the emitter was further carried out,it was found that the flow index of the emitter under the jet tee condition was lower than that under the constant pressure condition,the flow rate of the emitter under the jet tee pressure was lower than that of constant pressure condition.This means that the intermittent pulse wave generated by the jet tee can reduce the flow state index of the emitter,which can also improve the stable relationship between pressure and flow rate.(2)Through CFD unidirectional flow simulation,the flow field change process of the emitter was studied.It was found that the distribution trend of pressure and velocity in the emitter channel did not change significantly with time in the whole cycle under the condition of impassable pulse wave,and the pressure and velocity fluctuated continuously.Through CFD simulation of two-phase flow of sediment,the maximum sediment particle concentration and particle trajectory in the channel of emitter under different inlet pressure waveforms of high frequency(T=0.27 s)and low frequency(T=10 s)were studied.It was found that the particle concentration of emitter under high frequency pulsed flow was less than 0~14% under low frequency pulsed flow and constant pressure conditions.The trajectory distance was less than 0~19.4% of the trajectory distance under low-frequency pulsed flow and constant pressure conditions,which indicates that the high-frequency pulsed flow generated by jet tee can reduce the concentration deposition and particle trajectory in the channel of the emitter.(3)Through CFD simulation of two-phase flow of sediment,the order of cumulative particle concentration under high frequency pulse was jet tee pulse < triangular wave < trapezoidal wave < rectangular wave;the particle trajectory under high frequency pulse was jet tee pulse < triangular wave < trapezoidal wave < rectangular wave;It shows that the high frequency pulsed flow generated by jet tee can reduce the concentration of particles and the path of particles trajectory.(4)The experimental verification of jet tee shows that the anti-clogging performance of jet tee decreases with the decrease of inlet pressure in short period,and the amplitude and frequency of pulse flow generated by jet tee decreases with the decrease of pressure.Through sediment gradation test,it is found that jet tee had better anti-clogging ability for sediment particles with particle sizes of 0.03~0.05 mm and 0~0.03 mm.Most importantly,the average relative flow rate and irrigation uniformity of jet tee irrigation under different sediment content conditions were higher than those under constant pressure conditions,and the average number of times of irrigation is 3~8 times more than that under constant pressure conditions when the emitter was blocked.Through the long-period test,the flow decreased on both sides of the jet tee by 27.59%,28.2%,51.72% under the condition of constant pressure.The flow decreased under the condition of constant pressure were much higher than that under the condition of the jet tee,which shows that the anti-clogging ability of the jet tee to the emitter under the condition of long period is also higher than that under the condition of constant pressure.