Analysis On The Hydraulic Of A Dirp Irrigation Subunit And Experimental Study On Emitter Performance

Water resource constrain is the reality in our country. Considering the domestic water andindustrial consumption constantly diverted the share of agricultural water, how to make use of the limitedagricultural water to ensure food security is definitely a huge challenge. Developing water-savingagriculture is the inevitable choice to improve the water use efficiency. Drip irrigation is one of the mostefficient water-saving irrigation techniques. Recently, low-pressure drip irrigation became a research hotspot because of the energy saving characteristics. This paper choose the basic unit of a drip irrigationsystem which named subunit as the research object, study on the discharge and manufacturing deviationrepresent value of the emitter under low pressure condition, select several kinds of different dischargedrip tape to conduct an hydraulic performance experiment, finally discussion on a new drip tape layingmethod. The emitter discharge equation, the hydraulic performance and the drip tape laying method areanalyzed on the basis of the above experiments, comes to the following conclusions:(1)As the emitter operating pressure decreases, the manufacturing deviation represent value showsthe tendency of increase. This paper derived emitter discharge equations which take the emittermanufacturing deviation into account. When the drip tape of conterminal pressure(10m) applied underthe low pressure condition, using the emitter discharge equation,which is fitted at the low pressurerange(<5m) and took the manufacturing deviation into account, can make the calculated value and themeasured value more closer.(2)For the same laying length of different drip tapes, bigger rated flow as well as smaller distancebetween emitters results in a bigger friction losses. Brasuis equation (2-3b) and equation (2-6) can showthe friction losses of the drip tape when the laying length is smaller than200m.As the laying length ofthe drip tape increase, the calculated value and the measured value can’t fit very well, however.(3)The uniformity of the drip tape is affected by inlet operating pressure, laying length and terrainslope. As the laying length of the drip tape increase, the uniformity diminishes. As the decrease of theinlet pressure, the uniformity diminishes. Particularly, pressure reduction may lead to a bigger uniformitychange in the low pressure range. The inverse slope laid drip tape obtains lower uniformity. Topographicchanges has little influence on the uniformity when the inlet pressure close to the nominal pressure (10m),however, when the inlet pressure at the range of5~2m, the uniformity reduces significantly with theinverse slope laid.(4)Theoretical analysis shows that, folding laid drip tape can enhance the average flow rate of thedrip tape, but can’t improve the drip tape uniformity. Experimental results showed that, the emitterdischarge of the folding drip tape has a bigger emitter discharge compared to the single laid method. It’snot the2times the relationship. As the inlet pressure of the drip tape reducing, the size of the increasing will shrink. The folding laid method can’t improve the uniformity significantly, but remains the samelevel of the single laid method.