Effects of aeration on hydraulic and anti-clogging performance of subsurface drip irrigation emitters

Abstract

Abstract The hydraulic and anti-clogging performance of drip irrigation emitters are crucial factors that determine irrigation quality. Subsurface aerated drip irrigation (SADI) has been shown to enhance plant growth and yield, but further investigation is needed to understand its effects on the hydraulic and anti-clogging performance of drip emitters. Thus, based on hydraulic performance tests, the flow rate of emitters was tested under various design nominal discharges (1.0, 1.35, 2.3 L·h-1), working heads (2, 4, 6, 8, 10, 12 m), aeration amounts (0, 0.3, 0.5, 0.7, 0.9 L·min-1) and soil depths (0, 15 cm). In addition, the influence of nominal discharges (ND), working heads (WH), aeration amounts (AA), and soil depths (SD) on the flow rate as well as the flow index were analyzed. Moreover, the relative discharge of emitters was tested by short-term clogging tests, and the influence of aeration on the anti-clogging performance of the emitter was analyzed. A three-phase flow simulation method, based on one-phase flow and two-phase flow, was employed to investigate the variations in velocity, gas concentration distribution, particle passing rate, and concentration distribution of particles in the flow channel after aeration. The results demonstrate that the effects of ND, WH, AA and SD on the flow rate of the emitter were extremely significant(P < 0.01). The influence of ND and SD on the flow index was significant (P < 0.05), while the influence of AA on the flow index was not significant(P > 0.05). In addition, the negative impact of subsurface outflow on the emitter under high-pressure conditions (10, 12 m) was significantly less than that under low-pressure conditions (2, 4 m). After aeration, the number of muddy water irrigation times increased, and the growth rates of high-speed mainstream areas after E1, E2, and E3 are 3%-10%, 20%-46%, and 7%-17%, respectively. The particle passing rates of E1, E2 and E3 increased by 10%, 9% and 4%, respectively. This study can provide a research basis for promoting and using subsurface aerated irrigation.