Study On Operating Effect Of Two Typical Aerated Micro–irrigation Devices

Aerated micro-irrigation technology is one of the important directions for the development of micro-irrigation.Now there are not many studies on the operating effect of aerated micro-irrigation devices and a systematic technical support for the selection of aerated micro-irrigation devices.In order to explore the variation of dissolved oxygen,staying-time of bubbles in water and uniformity under different operation modes with different aerated micro-irrigation devices,analyze the difference of aeration effects under different conditions and then explore the suitable method of aeration,the ultra-micron bubble cyclic aerated device and the air compressor aerated device were used to conduct a comparative experiment to study aeration effects of two aerated micro-irrigation devices.The conclusions were as follows:Compared with the air compressor aerated device,the dissolved oxygen in the ultra-micron bubble cyclic aerated device decayed significantly with time.Aeration using both devices could obtain a better effect and lower energy loss when aerated time was about 5 min.Dissolved oxygen decreased with increasing water temperature.Therefore,in order to obtain greater dissolved oxygen,the effect of micro-irrigation aeration would be better at lower temperatures.Changes of length of the drip irrigation tape resulted an obvious impact on average flow and little impact on dissolved oxygen content.The drip irrigation tape with upturned drippers had more dissolved oxygen and a lower uniformity for dissolved oxygen than the other one with downward drippers.Ultra-micron bubbles had long staying-time in water and nice stability.The average dripper flow increased with the pressure head and was little affected by different dripper orientations.Compared with the non-aeration treatment,changes of both the average flow and uniformity for emitter discharge were not obvious using aerated micro-irrigation technology.The difference of average flow between different aerated devices was also small.The length of the drip irrigation tape had a significant effect on uniformity for emitter discharge under the two aerated devices,while dripper orientation had a significant effect only on air compressor aerated device.The uniformity for emitter discharge of the drip irrigation tape with downward drippers was higher than the other one.The uniformity of drip irrigation tapes with different dripper orientations increased with the increase of pressure and decreased with the increase of laying length.The outflow volume of different drippers was similar under different aeration volume for the air compressor aerated device.When volume of aeration increased,the overall trend of Christiansen’s uniformity coefficient(CU)was stable.The result showed that energy saving was achieved when volume of aeration was 3L/min,with best effect.The study enriches the theory of aerated micro-irrigation technology and provides the technical reference for the promotion and application of aerated micro-irrigation technology.