Head Loss Experimental Research And Numerical Simulation Of Orifice Outlet Low Pressre Drip Irrigation Laterals

Drip irrigation technology has become one of the most water-saving irrigation technologies in irrigation methods so far because of its water-saving, labor-saving, convenient management and increasing production. But there are many factors restricting the development of this technology. The low pressure irrigation system becomes a hot topic, because of having low working pressure, flowing slowly and evenly. In this paper, head losses rule of low pressure orifice outlet drip irrigation laterals were researched; applying experimental studies, hydraulics dimensional analysis and numerical simulation obtained the following main conclusions:(1)The total head losses of drip irrigation laterals increases along with inlet pressure and inlet velocity increases, which concur with the change trend of atmospheric pressure drip irrigation system. Meanwhile, the obtained orifice average flow and total flow rate with inlet pressure, orifice diameter, orifice spacing variation graph, but you can not get a uniform formula to determine the flow orifice.(2)Using Gambit software built model and Fluent software calculate to obtain the total head losses of drip irrigation lateral, this value is smaller with experimental value. But the deviation is not large, because on the capillary burr make orifice is coarse punch in experiment. So the local head losses of orifices are greater than the simulated values. However, due to the deviation within the allowable range, numerical simulation can be used instead of the experiment.(3)The comparison between calculated value using orifice coefficient method and empirical formula and experimental measured value of drip irrigation laterals total head losses results indicate the two formulas large errors are no longer applicable. So the use of dimensional analysis will affect the total capillary head loss the basic derivation of three dimensionless entries d2/DS, gD/v2 and ν/Dv, and by multiple linear regression analysis to calculate the total capillary head loss formula. Then according to the data used to verify the formulas formula established for verification. Finalized to calculate the total head losses formula of orifice outlet drip irrigation laterals under low pressure, which the correlation coefficient of 0.995.(4)The local head loss of drip irrigation laterals increases along with inlet velocity increasing. In the same velocity, different size drip irrigation laterals have different local head loss. The same inlet velocity, orifice diameter and orifice spacing, head loss of smaller lateral diameter is larger than in caliber big laterals.(5)The same inlet velocity, orifice diameter and orifice spacing, drip irrigation capillary local head loss as a percentage of the total head loss decreases with increasing capillary tube. The same inlet velocity and capillary pipe diameter, drip irrigation capillary local head loss as a percentage of the total head loss decreases with the increase of orifice spacing. And orifice spacing of capillary impact on the local head loss of total water head loss ratio. Different orifice spacing, capillary local loss of total water head loss ratio difference is obvious. In the drip irrigation system design, the local head loss of drip capillary cannot unite the 5%-10% of total water head loss calculation, or negligible. According to the differences between the capillary diameter and hole spacing take different values.