Anti-clogging performance of labyrinth emitters improved by sinusoidal wave dynamic water pressure

Abstract: Drip irrigation technology is one of the effective methods to solve the shortage of irrigation water source in arid and semi-arid areas. The emitter is the core of drip irrigation system, but the blockage of emitter hinders the development of drip irrigation technology. The sinusoidal dynamic pressure mode is expected to improve the anti-clogging performance of the emitters. This objective of this study was to clarify the influence of the combination of parameters of sinusoidal dynamic pressure on the outflow flow of trapezoidal labyrinth channel under muddy water condition. The sine wave dynamic pressure cycle parameters included amplitude, period and basic water pressure. The three factors with three levels each were designed by orthogonal design method. Based on previous studies and experience, the amplitude levels were designed including 2, 4 and 6 m considering the requirements of low pressure irrigation and avoiding negative pressure. The period levels were 1, 2, and 4 s. The three basic water pressures were 4, 6 and 8 m. A total of nine muddy water tests were carried out by using the method of periodic intermittent irrigation test. The muddy water concentration was 5 g/L. Meanwhile, tests with constant dynamic water pressures (4, 6 and 8 m) were also done in order to make a comparison with tests with the sine wave dynamic pressure mode. The measured and calculated indexes included the normal operating time, median size, low and upper particle sizes discharged from emitters and in the sediments of emitters. Range and variance analysis were used for data analysis. The results showed that the period was the only factor that could significantly affect the normal operating times, median size from discharged sediment and sediment deposition. The normal operating times of sinusoidal dynamic pressure under the water pressures (4, 6 and 8 m head) was 63.64%, 12.50% and 36.36%, more than that under the same constant pressure. The former had an average increase of 37.50%. Compared with the constant water pressure, the sinusoidal dynamic pressure was beneficial to the passage of sediments with different particle sizes. The upper limit, median, and low limit of particle sizes of discharged sediment were increased. Under the constant pressure, the large sediment particle size could easily deposit in the flow channel. When the sinusoidal wave period was 4 s, the amplitude was 2 m, and the basic water pressure was 8 m, the flow turbulence effect was the strongest, and the life of the emitter was the longest. Three different optimal results were obtained by range analysis for the three indexes. By a comprehensive score method with an entropy weight method, comprehensive score for each test was obtained. The range analysis of comprehensive scores showed that the optimal parameters were the combination with period 4 s, basic water pressure 8 m, and wave amplitude 2 m. Under the optimal conditions, the emitter could normally work for 16 times, which was 43.75% higher than the others. At this condition, the sinusoidal dynamic pressure can improve the anti-clogging performance of the emitter.