Nozzle mesh guide for water fountains

Build a homemade water gun or water balloon launcher and tell us about it.
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Silence
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Nozzle mesh guide for water fountains

Post by Silence » Tue Jul 15, 2008 2:52 am

MAKE just embedded a YouTube video about making laminar flow nozzles. I seem to have lost audio on my computer for the moment, so I'll take a better look later. In the meantime, just take a look at the footage 20 seconds in - it's amazing.

The nozzle looks a little bulky, but it works and the instructions are great. Kudos to author gryphern. He warns that the nozzle can't be used with high pressure (so there's not as much magic as you might think), but lower water gun pressures should be suitable, I think. Essentially, it's just a very well-crafted nozzle with screens. I'm not complaining though.

Edit: Ooh, some of the related videos are pretty neat, too.

aEx155
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Re: Nozzle mesh guide for water fountains

Post by aEx155 » Fri Jul 18, 2008 10:46 pm

I'm surprised no one commented in on this...(until now)

It seems like he's running it off of a hose, so I guess the pressures we use would be okay. The one thing I'm wondering about is whether or not not using a conical nozzle would affect stream performance. Obviously, it doesn't, but wouldn't we be able to get more performance if we used a conical nozzle instead of just a flat plane with a hole in it?

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cantab
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Re: Nozzle mesh guide for water fountains

Post by cantab » Fri Jul 18, 2008 10:51 pm

A conical nozzle would probably bugger up the lamination.

I think he reduces pressure by having a restricted inlet. The inlet is actually smaller than the outlet I think.

I think the main problem for our purposes is the use of scouring pads (or whatever it was) to remove turbulence. That will drastically slow down the stream. Screens should have the same effect, but to a lesser degree.

Basically, while the flow is indeed highly laminar, it's also slow. If the velocity increases, then lamination will decrease. But of course range will increase anyway, because the water's being projected 'harder'.

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SSCBen
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Re: Nozzle mesh guide for water fountains

Post by SSCBen » Sat Jul 19, 2008 1:10 am

For a conical nozzle it probably would be best to reduce the diameter first and then have straws. Though, the straws only act like small diameter pipes which reduce turbulence because the water can't move outside the limits of the pipe, which straightens the flow out, so an extension from the end of the reduction to the exit might work too on smaller nozzles.

Either some computational fluid dynamics or extensive testing needs to be done to determine if that'll be helpful though. It's too complex.

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cantab
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Re: Nozzle mesh guide for water fountains

Post by cantab » Sat Jul 19, 2008 8:17 am

There's another thread in this forum:

http://forums.sscentral.org/t5232/

JLspacemarine has done something similar, though smaller. He was using the CPS 2000 nozzle as a guide. It's basically the same principle as this.

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Silence
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Re: Nozzle mesh guide for water fountains

Post by Silence » Sat Jul 19, 2008 1:51 pm

Oh...that thread's from today...I was wondering why I hadn't seen it before.

JLspacemarine's pictures show how the lamination degrades as you increase the pressure, even with no nozzle screwed on the end. The Power Pak gets similar range and lamination as in the video, but increasing the output with the Flash Flood negates the advantages to some extent. So maybe this method doesn't scale up that much.

At a guess, I'd say a finer mesh could help solve the problem.

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cantab
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Re: Nozzle mesh guide for water fountains

Post by cantab » Wed Jul 30, 2008 10:38 am

The 'glass rod' effect looks cool, but is only impressive if the flow is fast. When the flow is slow, that's usual. I just got the same from a plain opening 35cm diameter with 40cm of water head (ie about half a psi). Similar can be seen with JL's design when connected to the powerpak with the full nozzle.
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aEx155
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Re: Nozzle mesh guide for water fountains

Post by aEx155 » Wed Jul 30, 2008 4:01 pm

I'm guessing, for water guns, we're not looking for the "glass rod" effect; this is here more or less to show how people make laminar flow nozzles (with straws and screens and all of that mess) and that it's very possible to get a coherent stream for as little as $15.

I think for the application of a laminator to be useful, you need to figure the optimum speed the water must flow at the pressure you're using while still maintaining a good stream velocity. You want a stream that's slow enough to stay together, laminar enough not to break up as much, yet fast enough to get to where you want it; that's a tall measure for people like us when you think about it.

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Silence
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Re: Nozzle mesh guide for water fountains

Post by Silence » Wed Jul 30, 2008 4:22 pm

But even then, surely you can distinguish between too much turbulence and a reasonable amount of turbulence. Supercannon II, the Mother of All River Cannons, and fire hoses all produce turbulent streams but clock tremendous ranges. Accepting turbulence in return for higher pressure *can* be worth it.

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