Study On Water And Sediment Movement Mechanism Of Labyrinth Channel Emitters

The use of water resources in China is extremely scarce,so it is imperative to popularize water-saving irrigation by using advanced technology.Drip irrigation is one of the most widely accepted precision irrigation methods.As the core part of drip irrigation system,the physical blockage problem of emitter still cannot be solved.In this study,two different types of emitters were selected to carry out anti-clogging experiments.The performance differences of the two emitters were analyzed,and the internal sediment movement mechanism causing the clogging of the emitters was discussed.In this study,two kinds of flushing water pressure modes(constant water pressure and dynamic water pressure)and three flushing periods(4d,8d,12d)were set up to analyze the anti-clogging performance of the pressure compensated emitter under different flushing treatments,analyze the influence of location factors on the clogging of the pressure compensated emitter and the effect under flushing conditions,and explore the mechanism of water and sediment movement in the emitter according to the characteristic sediment diameter discharged by the emitter.It provides a new idea for the optimization of drip irrigation system.Through the above research,the main conclusions are as follows:(1)The hydraulic performance and anti-clogging performance of the pressure compensation type emitter are better than those of the maze channel type emitter.In the clean water test,the maximum working pressure of the maze channel type emitter is only 0.15 MPa,while that of the pressure compensation type emitter is 0.35 MPa.At the same time,the service life of the pressure compensation type emitter is 268.75% that of the maze channel type emitter.(2)The reasons for clogging are different when the emitter is located at different positions of the capillary.The reason for the blockage of the emitter in the front section of the capillary tube is that the large particles of sediment settle and accumulate in the flow passage.The reason for the blockage of the emitter in the middle part of the capillary tube is that the larger particles of sediment are deposited at the entrance of the emitter and the smaller particles of sediment are deposited at the outlet of the emitter.The reason for the blockage of the emitter in the back section of the capillary tube is that the aggregates formed in the labyrinth passage by small particles of sediment.(3)Flushing treatment can significantly improve the anti-clogging performance of the emitter.Different irrigation treatments have different effects on the service life of the emitter.The dynamic water pressure increases the average service life of the emitter by 65.08%,and the constant pressure increases the average service life by 49.6%.The shorter the flushing cycle is,the better the flushing effect is.The service life of the emitter is only increased by 88.69%on average by high-frequency flushing.Among them,dynamic pressure high frequency washing is the best,and the service life is improved by 105.96% compared with that without washing.(4)Wash process there are three stages,namely,rinse insensitive period,flush the sensitive period,rinse invalid;Flushing phase front is relative and capillary flow change.(5)Flushing treatment can significantly reduce the sediment deposition in the capillary tube and the content of clogged sediment in the emitter.According to the test,the maximum sediment content of the capillary can be reduced by washing treatment by 55.54%.According to the statistics after the test,the maximum particle size of silt discharged from the emitter by washing treatment can be reduced by 76.67%.The particle size of V90 characteristic sediment from the emitter was maintained at about 3μm,which decreased by 71.3%.