Distance of throw of water jets

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Discussion Overview

The discussion centers on determining the distance of throw of a water jet in calm air, focusing on the relationship between nozzle diameter, water speed at the nozzle outlet, pressure at the nozzle inlet, and the angle of the nozzle. Participants explore both theoretical and practical aspects of the problem.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • Mauro seeks an equation for the distance of throw of a water jet, considering factors such as nozzle diameter, water speed, and nozzle angle.
  • Some participants suggest that knowing the exit speed and direction is sufficient for applying Newtonian motion equations.
  • One participant mentions that the trajectory of the water jet is not symmetrical, noting that the ascending part is longer than the descending side, which could lead to overestimations if symmetrical solutions are used.
  • A proposed mathematical model includes equations for vertical and horizontal motion, incorporating exit velocity, time, exit angle, and gravitational acceleration.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the best approach to determine the distance of throw, with multiple viewpoints and methods being discussed.

Contextual Notes

There are limitations regarding the assumptions made about air resistance and the specific conditions under which the water jet is analyzed, which may affect the accuracy of proposed models.

Who May Find This Useful

This discussion may be useful for individuals interested in fluid dynamics, irrigation technology, or those seeking to understand the physics of projectile motion in the context of water jets.

mauro
I need to determine the distance of throw of a water jet in calm air(no wind).
Is there anyone who has the equation ready as to say the throw T as a function of nozzle diameter, water speed at nozzle outlet (or pressure at nozzle inlet) and angle of the nozzle?


Thank you for any help you may have for me.

Bye
Mauro

PS How the air slow down a water jet? In case of a slug fired from a gun resistance is 1/2 C(ro)V^2 where ro is air density.
It is common experience to see that water jet trajectory is not simmetrical. The ascending part is much longer than descending side. Since I need to determine the distance of throw for a given jet, simmetrical solutions brings to grossly overestimation of the result.
Is there anyone with field experience, as for example nozzle manufacturers for irrigation purposes, willing to help me?
Or on the contrary a physics amateur with a theoretical formula?

Thank you to you all

Mauro
 
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If you have the exit speed and direction, its a simple Newtonian motion equation. You don't need anything else. You can also use pressure to calculate velocity if you need to.
 
like a projectile with the speed of the water at the exit...nothing else...
 
I think it is
y=vTsin(Θ)-g(T^2)/2
x=vTcos(Θ)
with v=exit velocity, T=time,Θ=exit angle above horizontal, and g=9.8 m/s^2.
 

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