museum exhibit

I am the exhibits designer for a science museum here in Florida. I was thinking about building a clear Plexiglas interactive nozzle for a water exhibit I’m designing and building. The reason for clear Plexiglas is so the visitors could see how turbulence in the water is eliminated. I would talk about laminar flow and make an exhibit the visitors would enjoy using. Our exhibits space has a high ceiling and thought it would be cool if the water went up pretty high, maybe 12 feet or so. I was thinking the stream would have to go up and come down pretty straight because I have to re-circulate the water. I was thinking I would position the nozzle a few degrees from plumb so the water would shoot up and come down into a fiberglass flower catch basin. I have read most of the posts and am thinking I would use an 8” diameter Plexiglas tube about XX” long. I have a question about the straws and the pump. I read that “magic nozzle” uses 7” x 5mm straws. Since this is going to be a permanent exhibit and will run 8 hours a day 7 days a week, will plastic straws hold up to water abrasion? Should I use glass tubes instead? Has anyone ever used glass? If so do you have an economical source for glass? Has anyone tried an electro magnet piston for the cutter? I read a little about a low pass filter, is that something I would need? What size recirculation pump should I use to get enough pressure for a 12 foot stream? I’m sure I’ll be posting more questions. Your comments and advice is welcome. I will have the budget to build a first class nozzle.
Thank you
Glenn

Hi there

Sorry for late reply !
But in the winter there is not so much traffic on this forum to much snow in the rest of the world

The idea of using plastic\acryl glass is no problem.
But remember there is actually pretty hard pressure inside the nozzle, so It can easy break if the glass is weak !
I do NOT recommend to use any GLASS at all, only plastic\acryl etc..

But I`m not so sure if you can see so much going on inside ?
Because most of the air is away when it enter the nozzle, so all you will see is blank water maybe

I dont think the straws or plastic will have any trouble with water passing 7 hour every day or more.
BUt you will need to change water maybe 3-4 times a week :-)


please share some pictures of your museum and location.
And give it a try .


Cheers

Filip
Norway

Hi Filip,
Thank you for your reply. I was planning on using a plexi tube with a hefty wall thickness, at least 12.5mm so that I can drill and tap it to secure the top plane. Do you think I should make the top and bottom plates square and use stainless steel rods to attach the end plates? Not sure how much pressure there will be. Is 12' high reasonable? What about the pump?
Glenn

12" high should be OK ..
The diameter is the most important.
I have 220cm in diameter (dont know how many " that is)

My pump is a 4500flow ! guess that is 4500ltr each hour
I did try 4mm glass on my nozzle, that did break

I dont think you need stainless steel on the top and bottom.
I have 5mm lexan on top and bottom , work great

But maybe you should consider to use 10 or thicker lexan plastic on the top and bottom so you can see inside better.

Did you mean 12' (feet) I guess that's about 4 meters?

I was going to use 12.5mm for the top and bottom plates. I have a 2 part plexiglass adhesive that is actually liquid acrylic and is very strong. I was going to machine a groove in the bottom plate and glue it. The top plate was going to be removable so that I can access the inside. I was going to drill and tap the tube to hold the top plate. The top plate could be lexan, but it does not glue very well so I would use cast acrylic for the bottom plate.

Did you mean 22cm diameter? that equals 8.5" diameter.

I'll have to find a conversion table for the pump.

sorry some misunderstanding!
I meant that my nozzle is 12" (inch) long, and 8.5" in diameter.

The height on my water from ground (nozzle) and up in the air is 2 meter !
I dont think I can manage to get it so much more than that, maybe 2-3meters, but after that the water will break!

Maybe if the nozzle is bigger in diameter you can make it stay laminar longer up in the air.

Thank you for your reply,
In the back of my mind I was thinking you might have ment 12" long. The reason for my building my own nozzle was to see what was going on inside, but if there is not much visually maybe I'll just buy a commercial unit. 2 meters high (6') is not enough. This exhibit will be inside, the visitors will jump up and try to catch the water. That would make a mess on the floor. Would I get more height if the gpm of the pump is increased? I guess I could mount the nozzle on a riser to get the water stream up higher to start with. Can you recommend a high quality commercial unit. I do remember seeing a post from someone talking about a commercial unit. Do they come with the cutter? You mentioned the stream breaking apart, how far would the stream travel? This nozzle is only one of many water exhibits. There will be another exhibit with a strobe to catch water dropplets in mid air, a water vortex, a water usage exhibit, this one I have not completely figured out. The exhibit would have a large plexiglas tank containing the amount of water used by the average person in a day. The visitors would be asked how they use water during the day, taking a shower, brushing there teeth etc. The water they use for each task would be transfered to another tank. They would see visually how they compared to the average. There will be a cylinder of water, oil and not sure about the third liquid. The liquid levels will represent the amount of water in the ocean, Ice and fresh drinking water. There will be several other water exhibits I'm still designing.
Looking foward to your reply,
Glenn

I dont know how high you can make the water travel !
Maybe you can calculate that in theory but that is not my strong side....

If you push harder with the pump (no matter what nozzle you have) the water will not stay laminar because of turbulence the pressure and airflow produce.

My only suggestion is to maybe make everything bigger!
If the nozzle is bigger in diameter, the water will also be travelling at a slower speed up to the output.
But the output will make it goes faster because of the same size !?! but this is something I have not tested.

The commercial nozzle is pretty expensive, Oase is maybe the best out there ?
My guess is that the one used in Vegas, Dubai and other exhibits are custom made .

I have recently made a small nozzle (5mm nozzle hole and 55mm bore tube) out of acrylic for a similar reason. I haven't yet got round to taking any photos of it, but hopefully will pretty soon.
As already mentioned, there is very little that can actually be seen when running as it is full of water, the the flow isn't really obvious. What it does do though is clearly show the construction of the nozzle.

Superpants
Thank you for your reply. Since there is not much to see inside of the nozzle. I will probably buy one. I can always do an illustration about what is going on and talk about laminar flow. Liteglow recommended the Oase. Do you agree with that recommendation ? It is a little expensive but I can save time. This exhibit will be interactive, we see about 750,000 visitors a year so I am expecting a lot of use. I am building 8 water based exhibit for our science museum and do not have a lot of R&D time. The museum I am with is expanding and these exhibits will go into the new exhibits space. The space will have a high ceiling. I would like to have a nozzle that will shoot water pretty high I’m thinking 12 feet (4 meters)would be great. When I spoke to the salesmen he told me I could get 15' I think that is (5 meters). My plan is to point the nozzle a few degrees from vertical and have it come down into a catch basin about three feet away from the nozzle. I’m looking for a large fiberglass flower to use as the catch basin. I will have to keep the exhibits floor dry and am hoping there will not be any splashing. I have seen a post on this site talking about other nozzles and do not have any experience with them. The Oase does come complete with a cutter and fiber optics option. Do you think the led would illuminate the water enough to be seen during the day? The ambient light will be pretty high since there are a lot of windows in the space.

Glenn, Your project definitely sounds interesting- I have been thinking of a similar project myself for some time. It’s good to hear someone else has been thinking along similar lines!

I have been very heavily involved with Scout events and have run activities at such events for up to around 4000 Kids. A lot of these have involved big games- It’s a knockout style or wet or messy games. One of the ideas I have been harbouring has been to build a waterpark with a range of activities (Slide, fountains etc) as you may find installed outside in a municipal park, but to include in this hands-on science exhibits that give the participants educational experiences as well as a fun activity. I had hoped to get this done this summer, but due to other commitments it’s not going to be possible. Instead I have been content to tinkering with ideas in the garage, including laminar nozzles. To the best of my knowledge an outside activity where kids can get wet whilst playing/ learning with the exhibits has not been done.

A couple of years ago I took a sabbatical and volunteered for 5 weeks in the exhibit development department of the Exploratorium in SF. I learnt an awful lot there and had a great time working with the team. Whilst they have some watery exhibits, they don’t have anything with the same potential to drench the area completely. Water will escape from the exhibits, so they use matting round the area to prevent the floor from becoming slippery. As I’m sure you will know only too well if there is a water jet is accessible they will get their hands into it, and with the size of the oase jet and the flow through it, there will be water all over the place pretty quickly, so I’d be looking at trying to stop the hands getting to the jet. Having said that canting it over a couple of degrees so that it falls almost vertically back down should help capturing it, although this may give you an issue with the LED lighting if you want it to make it back to the pool as the transmission depends on the flow remaining laminar. Running the nozzle close to vertical is likely to make the flow become non laminar close to the highest point of the arc.

I’m afraid I’m not familiar (other than what is published in this forum) with any details of the oase product so can’t really comment on the view-ability of the lighting in daylight or how high a stream can be got out of it. I would however expect that the light intensity would struggle to be seen effectively in a daylit space- certainly not enough for a full on Wow effect.

I have sent you a PM

I have been talking to a few sales people about the Oasa laminar jumping jet. I was a little shocked at the price considerding the simplicity of the process. As far as I can find ,the Oasa is the only unit that includes the cutter. I also understand that they are not being shipping to the USA any longer. Does anyone have any experience with the Oase? My plan was to have an interactive button the visitors could press to activate the cutter and not use the programmer. Do you think the cutter will hold up to a lot of use? I'm talking about several hundred times a day 7 days a week. I really want to have an exhibit like this in our science museum but it has to work. I could go back to my original plan of building one from plexiglas. I want to talk about laminar flow and this is a good example. I would apperciate any comments. I am told by the sales staff the the stream will only go about 7' (2.5 meters) high. Can I get better than that if I build one? My plan was to shoot the stream almost straight up since my exhibit space is rather limited. I don't want to have any water on the floor.

About the height of the water, I dont know... why not give it a try ?
Building the nozzle is fun and does not take long time, and you learn allot.

The cutter can be cutting all day long, I dont think that will be any problem.

Hi Liteglow,
Thank you. I have seen a few cutter ideas. Do you have any experience with any of them or maybe you have your own idea. I have allowed enough money for this exhibit so that I can buy the best equipment. I do not want to create a maintance nightmare. The Oasa uses a 1600 gallon per hour pump. Should I stick with that or buy something larger? I don't want to waste money by having to purchase a second pump.

I agree that visualization of the flow would be impossible only using water. However the use of a rheoscopic fluid is common for demonstrating flow. In fact ive seen it used in a museum exhibit before.

example
(he has a unique idea for flow straightening)
His setup uses mica powder and water to make the rheoscopic fluid.
There are pre-made fluids available for purchase but tend to be very pricey in large quantities.

An alternative to the premixed fluids are
concentrates
that are significantly cheaper

The only thing im not sure about is if the dissolved solids that make up the rheoscopic fluid would affect the cohesion of the laminar jet. Its non-toxic but im sure it could stain so isolating the jet would be crucial.

Hope this helps

Adam

Hi Adam,
thanks for your info. I have used this fluid in a flow visulation tank. The flow tank shows the turbulance behind different shapes. My exhibit will be setup using a pool of some kind, the fluid has to move or it will settle out of suspension. Powered coffe creamer also works. If my nozzle works out, I could build one using a closed loop.
Thanks again
Glenn

I just finished making several brass nozzles from naval brass. The chamfered holes range from 9.5mm to 19mm in diameter. I decided to use 4 each 6/32 brass allen cap screws to mount the brass nozzles, this will make interchanging them easier. I will machine a pocket in the lexan top to accept the nozzles. I am waiting for my 8" pvc pipe to be delivered. I bought 7.5" long straws yesterday. I have 2 linear selonoids on order. I did find a 1600 gph pump. I was told the nautilus pump is discontinued. I'm almost ready to start the assemble. Can someone help me figure out how to upload photo's so that I can post them on this site?

Thanks
Glenn

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Glenn,

Awesome Job! I'm really excited to see the results with the different nozzles. Please document as post as much information as you can as I am interested in the results too. I'm curious as to whether a larger stream would break up less if it travel the same distance.

WOW !!!

impressed, that rings is really well made
That will be great for the laminar flow.

Just remember (dont know if you already know this) that it`s very important that the TOP where the water hit must be totally FLAT !
So the brass rings need to be melted inside the top

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Here are a few photo's of my nozzel. I got a lot of great ideas from this forum and from watching parabolaqueous's utube video's and have used what I think are the best ones. I made a new nozzle from 316 stainless steel, john mentioned that the naval brass could pit over time. I machined an o'ring groove in the stainless steel. Hopefully that will seal it from leaking, not that would hurt anything. I wanted the nozzel to be easily removable. I did make another stainless steel nozzel with a smaller hole, having the o'ring should make changing it out easier. I made the body from 8" pvc. I made the clear top plate from 3/8" lexan. I machined an o'ring groove in that also. I found a foam that is used in pond filters. I'm hoping that will hold up a long time in the water environment. I'll send a few more photo's of the entire system. I made a low pass filter simular to the used in the utube video. I bought a 1900 GPH little giant pump yesterday. I'll have to buy a pvc valve so that I can bleed off some of the excess pressure. I should be able to try it out this weekend.

That looks great! Can't wait to see your tests with the different outlet sizes! Where did you get the brass to machine those nozzles? I have been looking but not exactly sure what to look for.

Great build !! when is there video :-)

I bought the brass from McMaster Carr.com. That's were I buy 90% of my stuff. They have quite an extensive inventory.
It will be a while before I'm ready for a video. I still have to build a cutter. I'm looking at using a pull/pull system. I don't know enough about electronics to build a push/pull selonoid system like
parabolaqueous built.

Thanks! Did you just buy a brass rod and then "chop it" into thin pieces?