Find Best Water Nozzle Type & Pressure for Longest Distance

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Discussion Overview

The discussion revolves around optimizing the type and pressure of water nozzles to achieve the longest possible distance for water ejected from a garden hose and inline water pump. Participants explore various nozzle designs, pressure settings, and the effects of flow dynamics, focusing on both theoretical and practical aspects of fluid mechanics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • The original poster (OP) reports various tests with different nozzle diameters and configurations, noting that smaller diameters can yield better distances under certain conditions.
  • Some participants suggest analyzing the entire system, including pump characteristics and losses due to nozzle design, to understand performance limitations.
  • One participant introduces "The Energy Equation" from fluid mechanics as a framework for modeling the system, indicating that additional information about the system is needed for accurate analysis.
  • Another participant emphasizes the importance of the nozzle entrance shape, suggesting that a rounded entrance could reduce turbulence and improve flow, potentially leading to greater distances.
  • There are discussions about the effects of adding more pumps to the system, with caution expressed regarding diminishing returns and performance implications.
  • Participants highlight the need for careful consideration of flow dynamics, including the impact of turbulence and the vena contracta phenomenon on water ejection distance.

Areas of Agreement / Disagreement

Participants generally agree on the importance of analyzing the entire system and the role of nozzle design in achieving optimal performance. However, there are multiple competing views on the best approach to achieve the longest distance, and the discussion remains unresolved regarding the ideal nozzle design and pressure settings.

Contextual Notes

Limitations include the need for precise measurements of system components, the complexity of fluid dynamics involved, and the potential for varying results based on different configurations and environmental factors.

  • #31
sophiecentaur said:
The Power of the jet depends on the velocity (mv2/2 per unit mass) and the velocity is inversely proportional to the cross sectional area (ignoring fluid losses for a given flow rate ). What you are saying seems to imply that there's no point using a nozzle and I'm sure you don't mean that.
I mean precisely what I said. The point of using the nozzle is to bring the flow to it as slow as possible ( minimizing transmission losses in the conduit, and then rapidly accelerate it through the nozzle. However, there is a balance to that. The resistive energies are proportional to ##\frac{Q^2}{A^2}## ( i.e. ##v^2##) too. You will never have a jet at the nozzle with greater kinetic energy per unit volume than the head the pump can supply at no flow. The first of thermodynamics says we aren't getting more out than what we put in and the second law says heat is always generated. period. So, we can't even recover what we put in.

EDIT: I struck through some less than accurate statements I made. I have allowed myself to be seduced by my own pump curves (characteristics typical of a centrifugal pumps). You can get higher kinetic energies than no-flow potential energy, so long as the pump curve has a local maximum at some## Q> 0##. I was too hasty in making the statement above. I apologize.
 
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  • #32
Mahonroy said:
... A quick overview:
My water pressure out of the garden hose is roughly 50psi with the end completely blocked off. Fully open I am getting about 5 gallons per minute of flow.

The pumps I have are 1.6HP, 1300GPH.
...
Please, consider that if your pump is forced to operate far away from that volumetric flow of about 0.36 gallon per second, it can be damaged, as the fluid will heat up rapidly within the casing and the hose.

 
  • #33
Did anyone in chemistry class shoot water out of a pipette? It would shoot a needle of water great distance (>10') with no turbulence. We would prank each other because you could wet someone's shirt down and they would never notice the momentum of the flow. The throw distance given the discharge diameter was insanely high.

My guess is the surface velocity is the limiting factor for laminar flow. That means there is no way to shoot farther.

Rather than focusing on the system upstream of the orifice, I'd focus on what is required downstream to achieve the desired distance. The fire hose (especially the fire tugs) is probably the best example.

When you deal with turbulence, I'm guessing it is striping away layers of the stream so to get great distance, you have to have more layers, i.e. a larger stream diameter.

There is probably a tradeoff between increased turbulence from increased velocity and flow diameter, so there is a peak efficiency to achieve the distance objective.

This is beyond my pay grade.
 

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