Analysis of changes of pressure before the orifices in laterals under low pressure drip irrigation |
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DOI:10.7606/j.issn.1000-7601.2009.02.32 |
Key Words: low pressure trickle irrigation lateral lateral head loss |
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Abstract: |
In order to study the variation law of low pressure trickle irrigation laterals under 0.5~2.0 m work head and different laterals with the length of20 40and60m orifice outlet drip irrigation laterals’linear pressure with a diameter of Φ16are measured.The results show that there are great differences between calculation results calculated by formula according to the specifications and measured value.Linear head loss calculation formula in specifications can not meet the orifice outlet drip irrigation laterals’head losses calculation under low pressure condition.Head losses of measured values is bigger than that calculated by formula for more than 30 times under condition of 0.5m work head and lateral with the length of20and40m and the ratio of them has the tendency of reducing with the increasing of inlet work head.After fitting by excel it shows that pressure distribution carried with laterals conforms to an exponent function relation which considers inlet pressure as a basic parameter and gives the experimental value range of related parameters as:head losses correction coefficient k=1.004~1.0183 and exponent correction coefficient θ=0.004~0.021. |