Experimental Study on the Multisegment Regime of the Water Flow in Drip Emitters
Publication: Journal of Irrigation and Drainage Engineering
Volume 136, Issue 4
Abstract
The flow exponent greatly determines the hydraulic performance of drip emitters. The objective of this study is to reveal the change of flow exponents with different water pressures. Laboratorial experiments of the relationship between discharges and water pressures were conducted with five types of drip emitters used for surface drip irrigation systems. The regression for calculating flow exponents was done with different segment pressures. The results showed that the flow exponent reduced gradually with the increase of the pressure segment except a brief increase in the early stage of pressure increasing due to the channel expansion. The eddy drip-arrow is most suitable for the pressure ranges of 2–8 and . The effect of the use of the small diameter drip-tube is best in the high-pressure range of . The relation between average flow velocities and water pressures is characterized by the flow exponent, the same as that between emitter discharges and water pressures. The eddy drip-arrow and the in-line drip-tape with a low discharge but a high flow velocity can meet the requirements of both prominent anticlogging and long-distance use. The Reynolds numbers of the five types of drip emitters range from 200 to 1,800, below the critical value of the turbulent transition of a conventional scale flow. The small diameter drip-tube needs the lowest Reynolds number required for full turbulence transition which assures a lower flow exponent when the emitter runs with a relatively low discharge.
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Acknowledgments
National Natural Science Foundation of China (Grant No. NNSFC50709011) supports this work.
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Published In
Journal of Irrigation and Drainage Engineering
Volume 136 • Issue 4 • April 2010
Pages: 254 - 260
Copyright
© 2010 ASCE.
History
Received: Feb 19, 2009
Accepted: Sep 14, 2009
Published online: Mar 15, 2010
Published in print: Apr 2010
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