The Effect Of Capillary Flushing On The Anti-clogging Performance Of Labyrinth Channel Irrigators

Emitter clogging is a pressing problem in drip irrigation system's extend application and using.Dripline flushing is an effective way to relieve emitter clogging and extend the economic service life of drip irrigation systems.To find a suitable dripline flushing combination of flushing velocity and frequency for drip irrigation systems using muddy water,this laboratory study was conducted to evaluate the effect of three targeted flushing velocities(0.3 m/s:V_0.3,0.6 m/s:V_0.6and 0.9 m/s:V_0.9)and four flushing frequencies(no flushing,flushing daily:F₁,flushing every three days:F_1/3,flushing every five days:F_1/5)on the emitter's performance(emitters discharge:q,statistical uniformity coefficient:UCS),blocking position of labyrinth channel and process of clogging.What's more,the particle size distribution of the sediment discharged from emitters and laterals or trapped in an emitter channel was analyzed by a laser particle size analyzer.the main conclusions are as follows:(1)The q,UCS and service life of the flushed dripline increased by 9.48?39.42,7.56?29.05,17.15?77.15%respectively in comparison with those in the non-flushed.q,UCS and service life increased with the increase in the flushing velocity;q,and service life reduced as the flushing frequency decreased;V_0.9F₁achieved the greatest flushing effect,however,the difference of flushing effect between 0.6 m/s and 0.9 m/s was not significant,and flushing velocities around 0.6 m/s would appear to be adequate when taking economic into consideration.(2)The more serious emitters clogging occurred,the smaller maximum grain size discharged from emitters:the maximum grain size was 65.94,36.71,20.43?m when the flow rate decreased to 90?100%q_ini?70?80%q_ini?40?50%q_ini,respectively.Sediments with particle size smaller than 25?m were easy to pass the labyrinth channel,and particles smaller than3.52?m had the optimum pass-ability,and not or slightly affected by clogging level.the sediments ranged from 68.31 to 97.45?m were separated by submain pipe and deposited in it,therefore,these particles were not transported in laterals.(3)The characteristic particle size of sediments trapped in flow path was smallest under V_0.9F₁;the maximum D90 of sediments trapped in flow path could reach 74.15?m,which was1.88 times as much as in muddy water;at the same flushing velocity,the particle size distribution range,characteristic particle size and the diameter at peak value of sediments trapped in emitters increased with the decrease in the flushing frequency.(4)In the aspect of clogging location,flushing could effectively relieve the clogging in flow path and exit orifice,but did not much affect the clogging in filtering inlet,and the total count of clogging location in emitter decreased with the increase in flushing velocity and flushing frequency.In the aspect of clogging process,sudden and complete clogging accounted for 62.38%of the clogged emitters.Flushing reduced the number of clogged emitters,and the repeatedly clogging were increased.(5)Flushing could transported sediments out of laterals effectively,the sediments weight in laterals with flushing was below 1 g,and far more less than those in laterals without flushing,which was 294.41 g.In non-flushing laterals,unit sediments deposition achieved maximum of 1.03 g/cm in the 11^themitter,and achieved minimum of 0.10 g/cm in lateral ends.In conclusion,Flushing can effectively reduce the accumulation of sediments in the dripline and decrease the probability of coarse particles flowing into emitters and fine particles aggregating and cementing in the labyrinth channel,thus relieving the emitter clogging.Therefore,dripline flushing can effectively slow down clogging in muddy water drip irrigation system.The recommended flushing velocity should be set at 0.6 m/s,and the flushing intervals should be shortened.Reducing the amount of laterals during a flushing to achieve higher velocity or increasing the duration of flushing would be an inexpensive means of increasing the adequacy of flushing.