University of Tabriz
Question
Asked 24th Feb, 2014
Is there a formula to calculate the wetted radius of a sprinkler?
The wetted radius (the throw) of a sprinkler is function of many parameters:
1- the pressure head
2- the the nozzle diameter
3- the throw angle
4- the sprinkler height
5- the nozzle interior design factors.
6- the type of the sprinkler whether hanged or fixed.
For the fixed type, I found some formulas to estimate the wetted radius like this lecture note http://goo.gl/Yj3pa0 Pages 36 and 37, however, it is not so practical equation.
On the other hand, I found nothing for the hanged type!
Can any one help finding a formula to estimate the wetted radius of sprinklers in irrigation?
Thanks in advance...
Most recent answer
Dear Mohammad
As you mentioned, "The wetted radius (the throw) of a sprinkler is function of many parameters".
I think the results of our study could help you to find the answer. Also Kincaid (2005) proposed an equation to predict wetted diameter in a no-wind and/or moderate wind velocity conditions:
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All Answers (11)
I work with mist heads and a bit more complicated atomizers and found that the same heads mounted on risers and 'hanged' from a ceiling generate different wetted radii. Hanging ones were giving a longer throw, but could not relate that to any function of a stem length (for water mist therr is also a problem of humidity and secondary breakup, you do not have). Another issue is that the avergage droplet size also influences the distance droplets travel, as it is related to the shape drag generated by every single travelling droplet moving in still air. In short, I believe there is no general or suitable formula, but you may have a chance in relating experimentally found wetted radii for sprinkler heads instaled on risers and for the 'hanging' ones.
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King Saud University
Thank you Jerzy for your answer,
The droplet size is directly related to the pressure head and the nozzle diameter, that's why I didn't mention it in the factors affecting the throw.
University of Tabriz
Dear Mohammad,
You might read the book of Jack-Keller (Sprinkle and Trikle irrigation...) and found relations there...
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King Saud University
Many thanks Fulvio, Keller's book is really important and I appreciate the e-Copy you kindly sent.
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Institut National de Recherche en Génie Rural, Eaux et Forêts (INRGREF)
Dear Mohammad,
You can use the empirical model developed by Heermann and Stahl (2006) to predict the wetted radius as a function of the nozzle diameter and the nozzle pressure. For more information you can go to the following reference: Martin, D.L., Kincaid, D.C., Lyle, W.M. (2007). Design and operation of sprinkler systems. In: Design and operation of farm irrigation systems, Glenn J. Hoffman, Ed., American Society of Agricultural and Biological Engineers, St. Joseph. pp. 557-631.
1 Recommendation
University of Tabriz
Dear Mohammad
As you mentioned, "The wetted radius (the throw) of a sprinkler is function of many parameters".
I think the results of our study could help you to find the answer. Also Kincaid (2005) proposed an equation to predict wetted diameter in a no-wind and/or moderate wind velocity conditions:
2 Recommendations
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