Large volume laminar flow machine
- Thread starter karimwassef
- Start date
herring_fish
Crazy Designer
Those seals work in US submarines but public displays have not had very good luck. They don’t have US Navy budgets or maintenance schedules but they have more access to money than I do.
I agree that YOU could probably spec some stuff that would work but this has been done several times and there is always a fly in the ointment. Given several design revisions you could work out the kinks but seals are a pain. Karimwassef has better skills than I do but if you lived in his town, I think that he would have better luck trying that one.
Burlington? …Shoot, you live closer to me than him. Maybe, I could get you to give me some practical advice from time to time. I could sure use it. :lol:
I agree that YOU could probably spec some stuff that would work but this has been done several times and there is always a fly in the ointment. Given several design revisions you could work out the kinks but seals are a pain. Karimwassef has better skills than I do but if you lived in his town, I think that he would have better luck trying that one.
Burlington? …Shoot, you live closer to me than him. Maybe, I could get you to give me some practical advice from time to time. I could sure use it. :lol:
karimwassef
Active member
Going back to Fiziks' comment on gyre tanks and the 3rd setup in this article: http://www.advancedaquarist.com/2007/1/aafeature
Back in 2007, the DC propeller powerheads we have today didn't exist. They also didn't use open inlets for massive flow. So adapting the concept to an alternating massive volume laminar flow wouldn't have been practical.
But the design is actually very similar to what we have here. It looks like there's a hidden section behind the overflow covered by a black plastic grate. The powerhead there pushes the water into an oval loop (gyre) that crosses the DT and then back into the hidden section. It alternates over hours, not seconds.
Having done the calculation for the RW20s and considering putting them into a sealed box, I think this can be made in even less space than the paddle. The key is the closed loop in the back and the two sets of massive, opposing, and phase synchronized propeller pumps. Follow that with a laminarizing box... And I think that does it.
Back in 2007, the DC propeller powerheads we have today didn't exist. They also didn't use open inlets for massive flow. So adapting the concept to an alternating massive volume laminar flow wouldn't have been practical.
But the design is actually very similar to what we have here. It looks like there's a hidden section behind the overflow covered by a black plastic grate. The powerhead there pushes the water into an oval loop (gyre) that crosses the DT and then back into the hidden section. It alternates over hours, not seconds.
Having done the calculation for the RW20s and considering putting them into a sealed box, I think this can be made in even less space than the paddle. The key is the closed loop in the back and the two sets of massive, opposing, and phase synchronized propeller pumps. Follow that with a laminarizing box... And I think that does it.
karimwassef
Active member
I'll still make a wooden box, but a simpler one now.
karimwassef
Active member
I know it's frustrating to go paddle-pump-paddle-pump... But when you bring up seals and leaks, I go back to the safety of pumps. 
JamesHolt
Active member
What causes the seals to fail...
I put an air-over-hydro cylinder on a coolant filter system..(speced with this same arrangement, teflon seals and orings, stainless cylinder tube)
regulated air on one side, nasty coolant on the other (pressure input), this balances a manual valve that controls coolant flow to two very large machines. It constantly cycles back and forth..
There has never been a rebuild or any leaks, and this is still in use 13 years later..
I put an air-over-hydro cylinder on a coolant filter system..(speced with this same arrangement, teflon seals and orings, stainless cylinder tube)
regulated air on one side, nasty coolant on the other (pressure input), this balances a manual valve that controls coolant flow to two very large machines. It constantly cycles back and forth..
There has never been a rebuild or any leaks, and this is still in use 13 years later..
herring_fish
Crazy Designer
Can that be scaled down?
Gorgok
New member
I know it's frustrating to go paddle-pump-paddle-pump... But when you bring up seals and leaks, I go back to the safety of pumps.
With pump outlets/powerheads you can gain some flow just placing them in ideal locations i think. Putting typical powerheads in the middle of the back loop will be worst case i think, as they end up fighting their own wake to generate more flow. But powerheads or closed loop outlets them right by the entrance of the return side of their respective loops the water they work on may get pulled further along like in a venturi. Closed loop outlets could also be angled in along the straight back for the same effect i think, just like fuel injection on an intake manifold.
Powerheads may be less ideal than a monster of a closed loop as well, as its harder to make flow past a typical powerhead laminar...
Typical powerhead design is actually lacking for this application as you are really after a propeller more so than a fan. A trolling motor is better suited to this idea... You could have those in the middle back and the little disruption to the flow it creates won't matter one bit the the time it curves back around the front. If you sized it right you could even turn it around when flow changes like an azipod... Or cobble up a Z drive unit out of something even slimmer and stick a motor out of the tank to drive it. Blended fish will always be on the menu though.
karimwassef
Active member
Going through the propeller ideas now
JamesHolt
Active member
The cylinder??
herring_fish
Crazy Designer
Yes can you buy stuff off the shelf that would apply to this situation or would it need to be custom. Maybe what you were talking about is already the right size.
JamesHolt
Active member
It wouldnt really be a cylinder, the piston chamber would be made from a large diameter piece of stainless pipe/tubing..
Probably around a foot in diameter..
Most of this would have to be made..
I just mentioned the cylinder when you said that about the seals not lasting..
Sorry,, didnt mean to lead the conversation astray
Probably around a foot in diameter..
Most of this would have to be made..
I just mentioned the cylinder when you said that about the seals not lasting..
Sorry,, didnt mean to lead the conversation astray
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karimwassef
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karimwassef
Active member
A propeller pump pulls water from around the head and pushes it through the front. This means it can be placed behind an acrylic wall with circular openings.
The openings are also large enough that when one side is blowing, the other is off and can act as an intake with relatively low resistance. The completely sealed mechanism means that the flow must be pulled through the back before it can be pushed forward.
This makes things much easier on one side... but then the problem is the diffuser.
This is the cone looking mechanism that's intended to take each propeller's output and convert it to laminar flow with an eggcrate to keep life out.
I decided against the slits or straws because I'm against mechanical filtration, so I'm using the "baffles" idea from the last iteration and converting it to a square diffuser baffle.
The openings are also large enough that when one side is blowing, the other is off and can act as an intake with relatively low resistance. The completely sealed mechanism means that the flow must be pulled through the back before it can be pushed forward.
This makes things much easier on one side... but then the problem is the diffuser.
This is the cone looking mechanism that's intended to take each propeller's output and convert it to laminar flow with an eggcrate to keep life out.
I decided against the slits or straws because I'm against mechanical filtration, so I'm using the "baffles" idea from the last iteration and converting it to a square diffuser baffle.
karimwassef
Active member
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karimwassef
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The 8 separate propellers should divide the flow into at least 8 equal blocks.
The large connecting "duct" should be large enough to handle the flow without the restriction of a PVC pipe.
The system is sealed and submerged, so it's a pressurized vessel.
I don't have a maintenance plan yet (as all pumps will need it).
The eggcrate won't keep everything out, but that means that the propellers can't go off completely. They'll have to be turning at low speed to deter encroachment. They're DC pumps, so that should be fine.
The separation of the directional pumps into each side means that they can't recirculate. This also doesn't require any fancy actuators or valve assemblies to waste energy.
It now comes down to the individual baffle / diffuser. I have to admit that I have no idea what I'm doing with this section... or if it's even something I can make.
I can probably get access to a 3D printer, but would rather find something pre-made for another purpose that fits.
The box openings are 8.5" x 8.5" and 5.5" deep. I'm even considering gluing LEGO blocks and covering them in epoxy to make this thing.
So anyone actually know how to create diffuser guides?
The 8 separate propellers should divide the flow into at least 8 equal blocks.
The large connecting "duct" should be large enough to handle the flow without the restriction of a PVC pipe.
The system is sealed and submerged, so it's a pressurized vessel.
I don't have a maintenance plan yet (as all pumps will need it).
The eggcrate won't keep everything out, but that means that the propellers can't go off completely. They'll have to be turning at low speed to deter encroachment. They're DC pumps, so that should be fine.
The separation of the directional pumps into each side means that they can't recirculate. This also doesn't require any fancy actuators or valve assemblies to waste energy.
It now comes down to the individual baffle / diffuser. I have to admit that I have no idea what I'm doing with this section... or if it's even something I can make.
I can probably get access to a 3D printer, but would rather find something pre-made for another purpose that fits.
The box openings are 8.5" x 8.5" and 5.5" deep. I'm even considering gluing LEGO blocks and covering them in epoxy to make this thing.
So anyone actually know how to create diffuser guides?
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herring_fish
Crazy Designer
LOL This time of night, that is a pretty good idea.
