Large volume laminar flow machine

It's just excel.

The colors on the graph -
Blue is velocity
Red is position
Green is acceleration (also Force)
Purple is lossless power
 
Looks like I would need to use acetone on a scaled down model to emulate the big tank. I can't scale the wall thicknesses, but I just need a proof of concept.

I think acetone melts acrylic though?
 
It's a spreadsheet tool from Microsoft.

So... Before I mock one up. Any other ideas?

I'm going to try one with tiny DC powerheads and another one with an actuated paddle.

Everyone think this is the best solution so far?
 
Remember as it relates to ideas: Volume not quality

This is another idea that won't be adopted as is but my spur something that might actually work. I hope that you will be entertained and not annoyed.

If the sides represent a throttling pinch point, could you angle the outlets to open the side channels? This is a VERY rough pic of what I am talking about but CAD could be used to draw out smooth transitions and enough straight area at the outlets to give the flow direction that you want while giving the maximum cross section so that the paddles are not pushing against the choke point.

ThrottleBody.jpg
 
I could also just open up the sides. I wanted to limit the "wasted" space on the sides to 12" on each side.

It also needs enough travel distance in the final direction of flow to make it laminar. I can't have a turn 1" before the exit and expect it to be laminar unless the flow rate is very very low.
 
As long as the side equals the back chamber in total cross sectional volume, you will be OK. In that case, it wouldn't be a pinch point. It just looked that way.

If so ..my mistake.
 
<a href="http://s1062.photobucket.com/user/karimwassef/media/1_zpsntsnc4h9.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/1_zpsntsnc4h9.jpg" border="0" alt=" photo 1_zpsntsnc4h9.jpg"/></a>

They're the same total width 11.5"

I didn't want to take more that 1ft on either side of the 8ft display for the mechanism.

But I need to keep at least a 5.5" straight run on the bottom channel to guide the flow in that direction.

The walls are 0.5" thick

So each channel can only be 1" wide.
 
Gone back and forth on scale and building material... cost, ease, etc... of the model build.

Here's my conclusion - I need a carpenter.

The scale is 1:2.5 = 2' x 4' wood coated with sealant...

My sump is a 150gal epoxy plywood, so I've done this kind of thing before.

This one just needs to survive for a week at most.

Maybe a thin acrylic top to see in.

So... Any carpenters?
 
Makes me wish I had a router so I can create 1/4" grooves for the baffles to fit into. Going to be hard to create a strong bond with vertically mounted 1/4" plywood strips otherwise.
 
Finally, (and this is not a rhetorical question. I really don't know.) Am I right in thinking that when you move one part of the tank water, you are moving it all so you have to calculate for that?

This will be a yes or no answer depending on how it is done..
If you are using a pump, the tank water moves for free (pump has to pull from somewhere). Just need to calculate for inertia of tank water..

With the paddles, you would just need to calaulate overcoming the inertia,resistance to being directed, and the momentum when you change directions.. :hmm4:

I dont think the idea with the paddles hanging down will last for long, it being offset like that and the forces on it will destroy linear bearings in short order..

The best bet for success with the paddles would be a rodless cylinder that can be submerged in SW.
That way it can push/pull from the center of the paddles.. There are also enclosed ballscrews setups that work the same way..

Second concern for the paddle setup as being shown is grease..
It will have to be lubricated and that lubrication will fall into the water, also when the bearing fails it will throw little balls and grease everywhere..

The idea of using wheels/cam followers will also need lubrication and be self destructive.. Plus the concern of broken parts/grease falling in the water also..

Since the calcs have be done for how big of a chunk of water needs to be moved, we/someone should be able to come up with a externally mounted driver and a piston chamber to meet the needs and not endanger the tank or its critters..

Dont take my comments as me being arrogant or an ***, I have been in industrial maintenance for 30 years and I tend to just blurt stuff out.. :spin3:
 
Thanks James.

I think a more robust solution is always better and the fewer the parts that need to be maintained, the better.

Since the displacement is only 4ft, it may be possible to do it with a linear actuator or driver. As long as I can control the acceleration/velocity, then it should work.

I've discussed the question of how much force is required with a couple of mechanical engineers. They both agreed that it would be a function of the displaced volume only. One of them came up with the conceptual idea of sizing the width of the display tank as infinite (looking as the limit). In that case, the force would only move the water it displaces since the water returning from the other end would never actually come back. In that case, is the force infinite? No... so the force cannot be a function of the total volume.
 
4ft, is that the total distance the water needs to move or how much you need to put in one side..
Also, gallon wise how much needs to be moved and how fast in seconds
If it is total we would need to push 2ft while pulling 2ft on the other side..
Either way a 2ft or 4ft push wouldnt be to hard to do, either pneumatic or a small Hydraulic power pak would work..
Could even use a screw drive to keep it simple..
Sorry, I never got into the engineering side more than just casual design, so alot of these formulas just lose me. I tend to base my stuff on my past experiences and failures..
 
If you have a piston below the tank, you will fighting seal failure. This is what has killed many a wave project. I think that you are closer with the last one.
 
Here's the design details

<a href="http://s1062.photobucket.com/user/karimwassef/media/1_zpsag2zkbak.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/1_zpsag2zkbak.jpg" border="0" alt=" photo 1_zpsag2zkbak.jpg"/></a>

and here's the wooden model dimensions in 1/2" and 1/4" plywood with an acrylic top

<a href="http://s1062.photobucket.com/user/karimwassef/media/2_zpsnyshmx5t.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/2_zpsnyshmx5t.jpg" border="0" alt=" photo 2_zpsnyshmx5t.jpg"/></a>
 
I also worked out the cost of doing it with embedded DC powerheads, 16 of them in the back channel with 8 in each direction. The channel is 12" x 20". The powerhead outlet only needs about 4" x 4", so this is actually viable...

Cost is $1840 and the peak power is only 320W (since only 8 are actually on at any one time). They do need to be enclosed in the acrylic mechanism though.

I haven't worked out the scaled model design variables - scaled speed, etc...
 
If you have a piston below the tank, you will fighting seal failure. This is what has killed many a wave project. I think that you are closer with the last one.

If you use the correct seal setup, it wont matter where it is located..
You would need a stacked setup on the piston..
At a minimum,, Cup seal, o-ring,o-ring,teflon slider, teflon slider,o-ring,o-ring,Cup seal

That way the cup does the work of pushing , the two o-rings do support and sealing, the sliders hold everything centered...
 
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