A Hybrid Computational and Analytical Model of Inline Drip Emitters
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v02bt03a018-detc2018-85871.pdf
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6.52 MB
Format
Adobe PDF
Checksum (MD5)
1ac48354593761d405b76fdc240a8312
Author(s)
Narain, Jaya
Winter, Amos G.
Date Issued
August 2018
Journal
Volume 2B: 44th Design Automation Conference
Publisher
American Society of Mechanical Engineers
Citation
Narain, Jaya, and Amos G. Winter. “A Hybrid Computational and Analytical Model of Inline Drip Emitters.” Volume 2B: 44th Design Automation Conference (August 26, 2018).
Version
Final published version
Abstract
This paper details a hybrid computational and analytical model to predict the performance of inline pressure-compensating (PC) drip irrigation emitters. The term inline refers to flow control devices mounted within the irrigation tubing. Pressure-compensating emitters deliver a relatively constant flow rate over a range applied pressure to accurately meter water to crops. Flow rate is controlled within the emitter by directing the water through a tortuous path (which imposes a fixed resistance), and then through a variable resistor composed of a flexible membrane that deflects under changes in pressure, restricting the flow path. An experimentally validated computational fluid dynamics (CFD) model was used to predict flow behavior through tortuous paths, and a pressure resistance parameter was derived to represent the pressure drop with a single variable. The bending and shearing mechanics of the membrane were modeled analytically and refined for accuracy by deriving a correction factor using finite element analysis. A least-squares matrix formulation that calculates the force applied by a line load of any shape, along which there is a prescribed deflection applied on a rectangular membrane, was derived and was found to be accurate to within one percent. The applicability of the assumption of locally fully developed flow through the pressure compensating chamber in a drip emitter was analyzed. The combined hybrid computational-analytical model reduces the computational time of modeling drip emitter performance from days to less than 30 minutes, dramatically lowering the time required to iterate and select optimal designs. The model was validated using three commercially available drip emitters, rated at 1.1, 2, and 3.8 L/hr. For each, the model predicted the flow rate with an error of twenty percent or less, as compared to the emitter performance published by the manufacturer.
MIT Department
MIT-SUTD Collaboration
Massachusetts Institute of Technology. Department of Biological Engineering
Massachusetts Institute of Technology. Department of Mechanical Engineering
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1115/DETC2018-85871
