Hydraulic performance and infiltration characteristics of emitter for sub-surface drip irrigation
WANG Haitao1,3, HE Qinghai2, WANG Jiandong1*, QIU Xuefeng1, WANG Chuanjuan1, MENG Xianwu4
1. Institute of Environment and Sustainable Development in Agriculture, CAAS, Beijing 100081, China; 2. Shandong Academy of Agricultural Machinery Sciences, Jinan, Shandong 250100, China; 3. College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, China; 4. Shandong Changjiang Water Saving Irrigation Technology Co., Ltd., Laiwu, Shandong 250022, China
Abstract：An emitter is an important part that affects the working performance and service life in sub-surface drip irrigation system. Aiming at an emitter for sub-surface drip irrigation(three flow specifications), the hydraulic performance of free outflow under different working pressures(0.02-0.14 MPa), the infiltration characteristics under rated working pressures(0.1 MPa), as well as the different buried depths(25 cm and 40 cm)were studied in this paper. The results show that the relationship between pressure and flow of the emitter conformed to an exponential function, which belongs to the type of non-pressure compensation emitters. The manufacturing deviation indicated a decreasing trend with the increase of working pressure under specific pressure, and the influence of emitter manufacturing deviation on the irrigation uniformity under low pressure drip irrigation system was more obvious; when buried in the ground, the shape of its wetted body presents an ellipsoid or similar sphere, at the same buried depth, the smaller the flow specification of the emitter, the smaller the wetted body formed at the same time; when the same amount of irrigation was reached, the larger the wetted body of the emitter with small flow specification. Under the same flow specification, the deeper the emitter was buried, the more unfavorable it was for the migration of the wetting front, and the smaller the wetting body formed during the same period. The diffusion distance and time of water migration in multiple directions are known to be power functions, and the water migration was the fastest in the horizontal direction. Secondly, as the emitter flow rate increased, the water migration direction gradually changed from downward dominant to upward dominant with time.
