Research On The Clogging Rule And Prevention And Control Measures Of Drip Irrigation Dripper

As a new type of irrigation technology,aerated drip irrigation technology has the advantages of coordinated regulation of water,fertilizer and gas in crop root zone,improvement of plant root zone growth environment,alleviation of crop root hypoxia,and improvement of water and fertilizer utilization efficiency,crop yield and quality.It has been widely used in the planting of vegetables,field crops and fruit trees.Underground drip irrigation is the best method of aerated irrigation,but the narrow channel of the emitter is easy to be clogged by particles,chemical precipitation,dissolved salts,microorganisms and other impurities in the water,which seriously restricts the application and popularization of aerated drip irrigation technology.Based on this,this paper taken the aerated drip irrigation system as the research basis and the inner inlaid chip dripper as the research object,using modern analytical techniques such as mathematical analysis method,field emission scanning electron microscope(S-4800)and laser particle size analyzer(APA2000),the emitter flow,clogging rate,clogging position,blockage mass and blockage spatial structure were compared and analyzed.The general law and basic characteristics of physical clogging of emitter and drip irrigation system under the condition of aerated drip irrigation were explored,and the internal and external factors affecting the occurrence law of physical blockage of aerated drip irrigation were determined.Finally,based on the anti-clogging test,the control method for physical clogging of aerated drip irrigation system was proposed from the aspects of emitter selection and lateral installation.The preliminary conclusions were as follows:(1)The aeration accelerated the clogging of the inlet grid,which lead to the clogging of the emitter.Compared with the muddy water drip irrigation system without aeration treatment,aeration accelerated the adhesion of fine particles at the inlet of the channel,increased the risk of sudden and complete clogging at the inlet of the emitter,and reduced the irrigation efficiency of the drip irrigation system.Among them,the muddy water with particle size of 0.075～0.100 mm had the fastest flow decline rate and the most serious clogging degree,while the muddy water with particle size of 0～0.100 mm had the slowest flow decline rate and the relatively mild clogging degree.During aerated drip irrigation,the emitter grid area,channel length and rated flow had a significant impact on the emitter anti-clogging performance and system uniformity(P<0.05),but the water inlet grid area had the greatest impact,that was,the larger the emitter water inlet grid area,the stronger the overflow capacity of sediment particles at the channel inlet,the lower the risk of clogging at the emitter inlet,and the better the anti-clogging performance of the emitter.(2)Aeration intensifies the deposition of small particles of sediment in the capillary.Compared with the muddy water drip irrigation system without aeration treatment,aeration increased the flow fluctuation,promoted the sediment transport in the lateral and the discharge of large particles,reduced the median particle size of silted sediment,and the influence of aeration on sediment transport decreased with the decrease of the maximum particle size of sediment.Aeration could promote the migration of large particles in muddy water with particle size of 0.050～0.100 mm,and aeration had little effect on its settlement so as to the quality of sediment in the channel was reduced.Aeration could promote the settlement of fine sediment in muddy water with particle size of 0～0.050 mm,and aeration had little effect on its transport,thus increasing the sediment in the channel.(3)Aeration could change the hydraulic performance of the emitter.Aeration increased the flow coefficient of the emitter,improved the flow fluctuation,reduced the flow pattern index,and reduced the sensitivity between flow and pressure.Compared with the non-aeration treatment,aeration increased the outflow flow of the emitter.The most significant key structural parameter affecting the hydraulic performance of aerated drip irrigation dripper was Mt-water inlet grid area,that was,the larger the water inlet grid area of dripper,the greater the influence of aeration on the flow coefficient and flow pattern index of dripper.(4)The "double" control measures to slow down the clogging of the emitter of aerated drip irrigation were put forward.Compared with the control group with smaller rated flow,smaller inlet grid size,longer channel length and downward emitter outlet during installation,selecting the emitter with larger rated flow and grid size,shorter channel size and upward emitter outlet during installation could effectively slow down the adhesion of fine sediment particles at the inlet of the channel so as to reduce the clogging risk of emitter inlet and improve the anti-clogging performance and system uniformity of emitter.