Abstract:In order to simplify the structure of rocker-arm sprinkler and improve its hydraulic performance, a jet sprinkler with double nozzles was designed by using negative pressure feedback technology, including jet elements, main and auxiliary nozzles and rotary sealing mechanism. The length of the main and auxiliary nozzles were 5.6mm and 4.8mm, respectively, and the elevation angle of the nozzle was 30°. The sprinkler was innovative in its mechanism and spraying method. The pulsed oscillating water flow can be formed between the main sprinkler and the auxiliary sprinkler by using the wall-attaching effect of the jet. The step-by-step rotating sprinkler can be realized by intermittent striking of the driving plate by the pulsed jet. The main nozzle of negative pressure feedback jet nozzle provided a long range jet, while the secondary nozzle jet struck the driving plate connected with it, breaking the whole continuous jet into small droplets, providing a jet with a relatively short range, and providing a rotating driving force for the nozzle, thus realizing full circle rotation. Under the inlet pressure of 0.20MPa,0.25MPa, 0.30MPa and 0.35MPa, taking range, average sprinkler irrigation intensity and sprinkler irrigation uniformity as evaluation indexes, the hydraulic performances of six different diameter combinations of main and auxiliary nozzles (3mm×3mm, 4mm×3mm, 4mm×4mm, 5mm×3mm, 5mm×4mm and 5mm×5mm) were compared by weighted scoring method. The results showed that under the above four inlet pressures, the jet nozzles with diameters of 5mm and 4mm had the best comprehensive performance. The water distribution was “triangular”, the range was 13.2~13.7m, the average intensity of sprinkler irrigation was 3.81~4.38mm/h, and the uniformity of sprinkler irrigation was 82.5%~86.0%. The results provided certain theoretical value for studying the hydraulic characteristics of negative pressure feedback nozzle and optimizing the nozzle structure, and brought ideas and applications for the nozzle technical field.
