射流三通连接滴灌带的水力性能沿程变化规律

为了探究滴灌带沿程水力性能的变化规律,在射流三通进口流量为0.1~1.2 m³/h的范围内,开展射流三通进口流量与出口水头振幅的水力性能试验,发现射流三通连接脉冲滴灌系统的流量阈值为0.2~0.8 m³/h;在脉冲滴灌系统流量阈值的范围内,开展射流三通连接滴灌带沿程脉冲参数试验,研究射流三通连接60 m滴灌带沿程脉冲性能的变化规律,发现当滴灌带进口水头振幅大于1 m时,沿程水头振幅的衰减速率存在突变点,沿程脉冲频率先增大后减小,射流三通在整条滴灌带上均能产生脉冲水流的进口流量设计范围是0.5~0.8 m³/h.在射流三通进口流量的设计范围内,开展稳压滴灌和脉冲滴灌的同台对比试验,结果表明,射流三通连接滴灌带内的水头损失比普通三通连接滴灌带内的降低62.5%~83.3%,灌水均匀系数提高了0.6%~0.9%,流量偏差率降低了1.2%~4.1%;进口流量为0.7 m³/h时,射流三通连接滴灌带灌水均匀度最高.

Variation of hydraulic performance of drip irrigation belts connected by jet tee

In order to investigate the variation of hydraulic performance of drip irrigation belts with jet tee connection,the hydraulic performance experiments of inlet flow rate and outlet head amplitude of jet tee was carried out in the range of 0.1-1.2 m3/h at the inlet of jet tee connection.It was found that the flow threshold of jet tee connected with pulse drip irrigation system was 0.2-0.8 m3/h.Pulse parameter experiment of drip irrigation belt connected jet tee along drip irrigation belts was carried out in the range of flow threshold of the pulsed drip irrigation system.The variation of pulse performance of drip irrigation belts of 60 m connected drip irrigation belt was studied.It was found that when the head amplitude of drip irrigation was greater than 1 m,there was a sudden change in the attenuation rate of head amplitude of drip irrigation belts.The pulse frequency of drip irrigation belts increased first and then decreased.The design range of the inlet flow of jet tee which could generate pulsed flow on the whole drip irrigation was 0.5-0.8 m3/h.A comparative experiment of steady-pressure drip irrigation and pulsed drip irrigation in the same stage was carried out within the design range of the inlet flow of jet tee.The results showed that the head loss of drip irrigation belt in pulse drip irrigation system reduced by 62.5%-83.3%,which was lower than that under steady-state condition.The irrigation uniformity coefficient increased by 0.6%-0.9%,and the flow deviational coefficient reduced by 1.2%-4.1%,when compared with that in the ordinary tee joint drip irrgation belt.When the inlet flow was 0.7 m3/h,the irrigation uniformity of drip irrigation belt connected by jet tee was the maximum.