Instructables

Laminar Flow Water Jet for Under $25.

This instructable is for everyone who has ever wanted to build a Laminar Flow Water jet, it sounds complex but it is actually very simple. You will need some PVC pipe, some brass pipe, about 300 straws, 4 test plugs, and some sponges. So lets get started!!!!

Here is a link to my second instructable that shows how to add lights to the water jet.
http://www.instructables.com/id/Laminar-Flow-Water-Jet-Part-2-The-lights/

If you have any questions or comments feel free to leave a comment, I don't mind if it is negative, you can always improve something when it is wrong but one its right there is no improvement.
 
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Step 1: Supplies

1) A foot long piece of 3 inch pvc pipe.
2) A 3 inch pipe cap.
3) A 6 inch piece of 1 inch pvc pipe.
4) A strong water proof epoxy or similar glue. (i.e. Marinetex)
5) A 6 inch long 3/8 inch brass (or copper) pipe with somewhat thick walls.
6) 200+ straws (if they are the bendy ones it doesn't matter)
7) 4, 3 inch test plugs.
8) Some 5 x 3.5 x .25 sponge/scrubbing pads. (if they are wider then that is fine, you want them to be thin though.)
9) A razor blade or even better a small bandsaw.


Tools)
 A small razor or exacto knife,  
Superglue
Sand Paper (light and heavy grit)
Garden Hose
Drill bit that will fit snug into the 1 inch pipe.

Optional)
Duct Tape
A band saw.
Electric drill
3 inch hole cutting bit(helps to round the 1 inch pipe)
Glue mixing supplies ie. Mixing board, stirring stick, applicator.
Various size brass pipe (for making different nozzles)
Extra 3 inch PVC Caps(these are a little expensive so i just used one.
darvin.t10 months ago
Hi. Do you have more photos or a project of this pool cover to share ? Very beautiful...
gilkyboy2 years ago
Great instructible. A cheap fix would be a pipe with an thin air bladder (or a balloon) inflated inside of it that all the water flows through. The air is compressible and so high pressure will shrink the size of the balloon, and low pressure the balloon can expand, evening out the flow.

Have you tried running your valve with a solenoid? I've always wanted one of these where it shoots "globs" of water.
gserrano7013 years ago
Fantastic, I'll have to try it sometime
Two things:
1.If the water goes through sponge-straw-sponge-nozzle, are that many layers really necessary? I would think the nozzle would be the deciding factor.

2.It is really cool, but what purpose does it serve? Even if you just made it to make it and to see if you could, that is still a purpose. I'm just wondering if you had other reasons.
The main reason for the layers is to hold the straws in place, the first sponge keeps the straws from falling out the bottom and the second sponge keeps the straws from getting pushed out by the water.

As for the purpose I thought it would make a fun project and I am planning on using it as a decoration sometime when I get the chance to make a more compact one.
rimar20003 years ago
Very interesting! I think that pretty and clean water jet can behave as a optic fiber. I don't know where to put the led, for not interfere the laminar flow. May be you have the response. Thanks for this very good instructable.
crapflinger3 years ago
you need more detailed pictures/drawings/explanations of most of the steps. i understand the basics of what you're doing (i think we saw the same TV show) but i'm not exactly clear on where all of the components actually go in this particular contraption you basically lost me at step 6. after reading over it about six times, i think i get it ...you're basically just getting a smooth plastic ring...i'm not sure why. is it just to hold the sponge against the side of the pipe? then in step 7 you're making another ring for the top end of the straws? a picture of the inside WITH the straws and such in it would be really helpful
scottrevoman333 (author)  crapflinger3 years ago
Ok sorry for the confusion I am currently taking and trying to add new photos, and to clarify step 6 you need the side ring from the test plug to hold the sponge in place, you will need one sponge at the bottom top keep the straws from falling out and one at the top to keep them from getting blown out from the water because you don't want to tightly pack the straws, the best way to pack the straws is to fill the pipe with a good handful of straws and then put more straws on top of them and hit the tube on the sides and bottom until no more straw will fall in on their own then if there is an open space just stick a straw i the space.
dchall83 years ago
LOTS OF STARS!
I really like this! I'm an aero engineer and enjoy fluids projects.

Where did you get the know-how to build this???

Just a few thoughts/questions:
Is there any reason you could not use a plastic nozzle instead of brass or copper?  Both of those metals could erode although under laminar flow conditions, quite possibly they will not.  Still, I would think plastic nozzles would work just as well. 

Why do you taper the inside of the nozzle?  Which side has the small side of the taper (inside or outside)? 

Is there any reason you did not use PVC glue where it would work best?  The one place it would not work is in attaching the inflow tube. 

The inflow tube is obviously supposed to generate a swirl.  Is that just to standardize the direction of water flow before straightening it out?  I was wondering if you could have brought the water in from the bottom using standard connectors and fill the bottom of the chamber with marbles to break the flow. 

Is there any reason you did not attach a female hose connector at the input?  They are available in PVC at the home stores. 

Does it matter how long the straws are relative to the outer pipe?  Are they slammed up against one end or the other or do they sit in the middle of the pipe?

I think the reason for the scrubbing pads is to hold the straws in place without restricting the flow.  The flow is already very slow because you brought water from a 3/4 hose into a 3-inch diameter pipe.  It is like filling a bucket - slow.  The scrubbers would also help stop eddy flow at the entrance and exit to the straws.  And are they plain scrubbing pads or the kind with sponges on one side? 

Thanks for this.  It is a very practical project that is easy for kids to do.  I hope it gets some of them excited about fluid flow!!
scottrevoman333 (author)  dchall83 years ago
Ok so where to start, I first came across the design whlie watching a tv show and they explained how it flows through straws (usually a special molded piece) but that would be very expensive then i continued to look for info on them and found a video on youtube of a man that built a very nice one but it was much to expensive for me, as for the nozzle i use brass because its what I had on hand and it creates a very smooth flow but a plaistic nozzle could possibly work too, also the taper creates a very fine edge and it removes any stray filings from cuting it, the edge makes it easy for the water to form into the laminar state. As for the orientation of the nozzle the fine tapered end should face the inside of the tube so the stream is essentially "cut" by the nozzle. The reason i didn't use PVC glue is because I need to still be able to open the tube and check it and in my other instructable I added an LED to it. As for the marbles you would have to experiment as i figured out if the hose gois directly into the bottom then it will create a stream that move faster than the rest of the water (esentially like sticking a hose in a pool and turning it on). The reason I didn't use a female hose adapter is because i didn't have one on hand. (I basically used what I had laying around). The length of the straws I don't think matter but you can experiment, and they are not packed in they are kinda comfortably sitting in it (I will post a picture as an example). Your right that the scrubbers don't really slow the flow but they mainly hold the straws and it helps remove any streams of water as mentioned earlier.
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