[Khalid]

Hi Harry and Pavlo,
If this is pressure sort of energy to drive the water through the nozzles then it will be difficult for me to experiment(flame2)
As far as water Head concern, I think this will have a minute influence on gravitational forces..As all the drops has to be pass through the similar diametrical tubes so i hope the image will be very little distorted as the drops falls near the bottom of fountain.
I just came to my workplace and today i will experiment and hope to submit a video on the Youtube.
Regards

[epineh]

One simple way to add a little extra pressure would be to place the holding tank a little higher, water pressure increases quite quickly with a little extra height, may be a simple solution for experimenting at least.

Russell.

[PEU]

I recall viewing one of the patents about waterfalls and they use a tank above the solenoids for just that, to increase pressure.

Waiting for the video Khalid!

[Khalid]

Russell and PEU..
Off-course the tank will be at a height of 9feet and the solenoid will almost a feet below the tank. I have made a simple setup to test the solenoid with different real-time delays in the software. I think when all 40 valves will be operated the result will be stunning.
I have just installed the IN4007 across the solenoid and with no resistor/capacitor. the whole setup is running with 24VDC supply.
In the next video i will try to install the resistor/capacitor as suggested by Roman.
Enjoy the following video:
[nomedia="http://www.youtube.com/watch?v=AlO8cQJcojg"]YouTube - graphical waterfall Single Solenoid valve testing.wmv[/nomedia]

[PEU]

My impression is that the setup needs a little more pressure, by your eye, whats the smallest "dot" you can make and still see the gap to the next dot?

[Khalid]

Hi PEU,
Here i think is different philosphy.. If we keep the water under pressure, then the speed (Kinetic energy) just leaving the nozzle will be very high and the shape of water droplets will be oblong etc...
I think the water in overhead tank should be on atmospheric pressure, and the solenoid operating speed may be increased so that fine shape drops can be formed and visible separately...
I welcome suggestions from you ...

[RomanLini]

Khalid, I believe the amount of water that flows through the orifice will depend on the pressure, the problem is that if a few solenoids open together the pressure in the manifold will be reduced, so you will get different drop sizes etc depending on how many nozzles are open.

The solution involves maintaining a constant pressure in the manifold, which you can do with gravity feed if you keep the same water height AND have quite a large tube from tank to manifold.

A better solution would be to feed the manifold from mains water pressure, with a pressure regulator to give a small but very constant pressure inside the manifold at all times. That would probably be my preferred solution, it's a bit neater with no tank needed, and will work best with a constant pressure. You may also need a small pressure "accumulator". Some of your friends in the refinery might be able to advise you about the hydraulic (or pnuematic) regulator and accumulator.

[Khalid]

Thanks Roman for the great idea of pressure pipe with regulator. It seems easy but first i have to increase the response time of the solenoid.

I have added 50V 220mfarad capacitor and 45.2Ohm 1/2 watt resistor in the circuit. I am still using the 24VDC power supply, just to check response. The result is very good and you can see at 0.2second time i am getting droplets... I think this response will certainly be increased if i use 32VDC power supply and 47Ohm 3watt resistors with 220mF 50V capacitor.

In my locality i have only up to 1 watt of resistors... can i make a combination to increase the wattage?
The video is uploading on youtube ...i will post the link soon..

[PEU]

look at this quick draft:



Atmospheric pressure should be OK but, as Roman also noted, you will need to have enough water over the solenoids to keep pressure constant, its not the same to have 20 solenoids open than 80 or more.

Also, the droplets, or dots as I like to call the smallest drop you can make, will accelerate until a certain speed and after that the velocity will be constant, if you achieve this speed at the nozzle, with pressure, then the speed will be uniform from top to bottom, making drawing easier IMHO.


Pablo

[Khalid]

Hi Pablo,
Thanks for posting the sketch.. I now absolutely agree with all of you... I have to check my solenoid valves passing problems at some pressure (a little above atmospheric)... I also agree that the constant pressure will keep the uniformity of all solenoid valves droplets.... Now, just thinking an easy way to implement..
To implement this constant pressure i have to continuely dose the water in the header. If the Header is pressurised upto 1bar then it will be enough..but How i can stop the pump considering the pressure is reached little above atmosphere?... I think the centrifugal pump with some relief valve will be required:stickpoke
Here is the video
[nomedia="http://www.youtube.com/watch?v=jNYbcgg1fx0"]YouTube - Increasing solenoid response with resistor/capacitor addition.avi[/nomedia]

[harryn]

The wattage of resistors is additive. For example, suppose you wish to have 1 ohm x 2 watts.

2 resistors in parallel follow the rule 1/R1 + 1/R2 = 1/R total. So if you use 2 ohm resistors, 2 in parallel will give you 1 ohm. For more resistors, you just keep adding more in the same formula.

Each resistor can handle 1 watt, so the total is now rated at 2 watts. The total heat must still be removed. Also, resistors and capacitors tend to break if run near their ratings, so keep this in mind.

I watched again the fountain, and also notice the lack of fine drops or mist from the action of the valves. This makes me wonder if they have added "something" to the water to make the droplets stay in a constant size and form.

I was thinking originally of a surfactant, but this would tend to lower the surface tension (increase flow rate, decrease tendency to be round). Perhaps a little bit of alcohol instead. I am still thinking about this part.

[neilw20]

Is this the final result?

[Khalid]

Hi Neil,
The links are stunning and i simply flabbergasted...I really like the Sword falling on the car.. and the picture shows blobs of water just after the nozzles.. what about the pressure

[diyengineer]

WOW i had to comment so i can read this entire thread later. Simply amazing. How is the project Khalid

[TarHeelTom]

One simple way to maintain constant water pressure is to mount a supply tank several feet above the solenoids. The higher the tank above the solenoids, the higher the pressure to the solenoids. Roughly 0.433 psi per foot.

My feeling is that using a higher water pressure will result in more well defined drops.

Now use a small pump to take water from the catch tank under the fountain to the fill the upper tank. The flow rate of the pump needs to be slightly more than the flow with all the solenoids open. A pump which is slightly too small could be compensated by simply adding some delays in the program between logical display groups. The pump replaces the brave women.

Use a simple overflow tube, attached to the supply tank very near the top of the tank, to take water from the tank to the catch tank. This overflow tube needs to be large enough to allow ALL the water from the pump to overflow back to the catch tank. The overflow tube should extend below the water level in the catch tank, to keep the noise down.

Tom

[TarHeelTom]

Aside from using colored LED's, there MIGHT be another way to build a color display.

If one had three tanks above the solenoids, with three solenoids per dot position, you could have red, green, and blue dots, possibly with all the colors coming from a single nozzle.

Success of this system would involve some chemical research, and I'm not a chemist, but perhaps we have one here on the forums.

We need to find three different fluids, each with a different specific gravity, the more difference the better. These fluids should be fluids which would generally not mix with each other. Oil and water, for instance. Each fluid would be treated with a different color dye.

From the catch tank we would have a drain line, or a pump and line, into a taller, but smaller diameter, separation tank. This tank might have to be several feet tall.

The three different fluids would settle into three different layers in the separation tank, very similar to a petroleum cracking tower, but gravity powered.

Three different outlets, at different level, in the separation tank would allow three brave women to return the three fluids to the three supply tanks. Probably a good idea to put optical monitors above and below each outlet to allow pumping or draining (a solenoid valve?) only when the particular color is available at the outlet.

To my knowledge, most display fountains recycle the water, and only use mains water to replace evaporation or leakage.

Tom

[diyengineer]

It would be cool to enclose this contraption in a vacuum chamber, then the water would "rain" even faster. Whether its top speed would be faster or acceleration would be faster, i don't know. Gravity wouldn't change obviously but the lack of air in the way would surely be removed. You could place a check valve over each solenoid. I don't know how you would go about recycling the liquid though, and the other engineering feats it would take, let alone $. Just a thought.

Very very cool though

[lgalla]

The water would boil or vaporize in a vacuum chamber.
Larry

[PEU]

IMHO 1st thing that needs to be done is have consistent results, then go with the niceties such as color, complex pressurization, etc

[harryn]

Hello, I like your videos, especially the one of controlling the stream of water.

I am trying to determine if your on/ off switching is fast enough though. Would it be possible to make a video of perhaps 10 seconds each of various short switching times ? I would like to get a better look at the drops for shape, spacing, etc.

As far as acheiving constant (low) pressure, this is not too hard. Suppose you wish to have a head pressure of 0.3 meters. Just have an over flow pipe as tall as the pressure you wish, and let the excess water flow down inside of the overflow pipe. Just make sure it is vented to atmosphere.

If you want even higher pressure, say perhaps the same as your pump pressure, then just dead head the flow into the header pipe. Most pumps of this type will not go higher than 3 - 4 bar absolute pressure. The air trapped in the header pipe will help to soften any pump vibrations.