Backyard Aquaponics
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Does anyone have any links to information on how to create a "free surface vortex" ie one that sucks in air.

I found lots of information on how not to do it but it is very general in nature. I cant find anything on how to get them to form on demand.

I think it must be proportional to velocity and submergence but I'd love a paper that discussed it.

Anyone?

Is this the effect you are trying to create?





If so then I'll reference my fluid dynamics book when I get back to work.

Here is a link to get the brain juices flowing and might lead to some relevant stuff: http://www.manciniconsulting.com/Discussion/Topic5Vortices.html

In that link above you can see the similar compression throat as in the video.


Or are you trying to do something like this?



Here are some equations related to that: http://www.nptel.iitm.ac.in/courses/Webcourse-contents/IIT-KANPUR/FLUID-MECHANICS/lecture-14/14-3_pressure_dist_fre_vortex_flow.htm

A PDF about "irrotational vortex"

http://www.atm.ox.ac.uk/user/marshall/ffc/lecture5.pdf


And another link with a "Vortex Brewer". A bit new earthy but some good R&C "research & Copy" might be found there: http://www.vortexbrewer.com/

Ouch my brain hurts now

Big problem is that them vortexes are not good for the pump. I think its the turbulence that cause vibration which damage the impeller?

If you find a way to make them work it could be a great way to aerate a system?

Please share if you find a way!

Thanks Kimocal.

Yes Gabe the first is very, very, very bad for the pump. All sorts of effects stack upon the other and at best lead to inefficient operation and at worst lead to dead pump.

The second was what I was after I'll look through them this morning to see if they have everything I need.

A good reference on the former and how to avoid them is the Pump Handbook:

http://www.amazon.com/Pump-Handbook-Igo ... k+Karassik

ARGH!

It would help if the terms were all defined.

A few things make sense though. There is pressure inside the vortex which is why the air column forms. The greater the air pressure the deeper the air column. Which now that I think about it...duh!



So you need to know the velocity of the vortex. Sure, which is determined by equation 14.10.



There is no equation 14.1 and the previous button doesn't work.

ok I got the previous button to work and found equation 14.10.

Know I need to know how to determine constant "C" and what is "r"?

Can you explain more what you are trying to solve exactly? Give your knowns and what you are trying to solve in a bit more detail.


Here is another PDF with some equations to toss around:
http://www.freestudy.co.uk/fluid%20mechanics/t5203.pdf

Scroll down to section 10. VORTICES. I'm guessing you are trying to induce a vortex from a flow of water maybe? If so set your Tangential Velocity to that of the velocity of the incoming water if it is at the outer edge/radius of a circle. So for example in this video....




Assume that the vortex height = z and that the outflow rate = inflow rate

If you substitute Vt = w*r ---> Tangential Velocity = (rotational velocity) * radius

Then solve for z...

z = (Vt^2) / 2g

You can see that the vortex height is determined by the square of the Tangential Velocity. That's a very simplified breakdown with big assumptions and doesn't account for losses due to friction but it should get you pretty close I'm guessing.

Mostly it for a greater understanding of the flows in various system components.

Specifically what effect does the size of the drain have?

Under gravity at what depth will a vortex be "free surface flowing" for a given outlet size.

Can you calculate the amount of air that is entrained by the vortex into the outlet?

What effect does air pressure have on vortex formation (now know this one, ie less air pressure smaller vortex)?

What effect does the container size have on Vortex formation/development size ie in a vertical pipe (smallest), bucket or tank (largest).

If the purpose is aeration, why not try a Venturi design such as this:

http://www.lagunakoi.com/Venturi-Tees-P ... c-159.html

Purpose is not aeration.

That was a vague response, now we must know why you want to create one!

So, now I'm intrigued.... considering...


Why the need to suck in air then???

Silenced wacky tobacky water pipe.

Moderator , I think he is trying to understand the speed of flow in a system, they can be interfered with by a vortex; there again Stuart believes in mathematics so who knows.