1:24 water tunnel for flow visualization

[theycallmeebryan]

I can see I'm not the only one that thinks the idea of having a scale model wind tunnel in their home is the coolest ecomodding toy one can own!

[Vekke]

Originally Posted by theycallmeebryan

I can see I'm not the only one that thinks the idea of having a scale model wind tunnel in their home is the coolest ecomodding toy one can own!

My wife does not think that way, but I do.

[aerohead]

Originally Posted by Vekke

Since no better info has come conserning the length it will be at the first tunnel that 1260mm long. Inner corners are done and also the reinforcement glasfiber layers to hold the corners and keep the water out of the seams.
DIY Water tunnel inner corners.jpg - Windows Live

Tomorrow target is to get outer corners and ready glasfiber layer to whole inside so I can add water. Still wondering will I buy boat electric motor or build similar wheel like here any ideas which would be better? that wheel is no problem but how to be able to control rotating speed is a problem and also at what speed :/.

Costs so far:
Glues 25€
bolts 20€
wood 15€
glasfibers stuff 15€

time=priceless .

This would be a water 'table',rather than a wasserkanal/water tunnel.
Your flows would be only 2-dimensional and it would be impossible to evaluate wake flow.
You can analyze center-line body flow though.
Texas Tech has a water table.They pump water to an upper reservoir where the water bleeds through a porous media onto a slightly slanted backlit glass sluice.The water flows down by gravity.Simple!

[Vekke]

Originally Posted by aerohead

This would be a water 'table',rather than a wasserkanal/water tunnel.
Your flows would be only 2-dimensional and it would be impossible to evaluate wake flow.

Is that not 3D if my water "table" is 750mm deep/high? Mythbusters version was just like mine...

[khafra]

Aerohead was referring to the video. These days, they still use setups like that, but with a transparent bottom, and they image the light refracted through. It offers a decent way of approximating compressible flows in 2d, like those that happen inside a jet engine.

If the water's 750mm deep, and the model and flow speed are scaled appropriately to that, it'll be a 3d simulation.

[aerohead]

Originally Posted by Vekke

Is that not 3D if my water "table" is 750mm deep/high? Mythbusters version was just like mine...

Vekke,750mm sounds like a good direction.With the heat we're having here I'd be tempted to 'dive in'.
Wind tunnels attempt to limit the frontal area of the model to 4-5% of the test section cross-sectional area.This might be a good general rule for any tunnel regardless of 'fluid'.
Alan Pope,in his book,was pretty adamant about blockage ratios.
If you're around that figure you should have great results.
I'll look forward to future posts.Great project!

[ecomodded]

I want to make test tank , I have a 3ft long empty fish tank to test in , I am thinking to use it as the video test tank , with water flowing into and out of the tank so the dye leaves the tank water after being flowed. This off the top of my head so the plan is in its infancy ..

edit: My tank theory seems sound , here is test tank set up done by a university aerospace department -
http://elearning.eng.cu.edu.eg/aeros...gprojects&id=3



a tester testing in his tank

https://www.youtube.com/watch?v=wm_hX4QpfP4

[freebeard]

3ft long?

This was my proposal for a water tunnel, using paddle wheels to reduce turbulence. It wasn't very well received.



It could work with two, or only one wheel. Then you could put a window in the side of it.

[user removed]

I think if Vekke does not give his brain a rest the heat generated is going to melt the polar ice cap. He's pretty close.

How about an inclined plain using gravity to keep turbulence low, or a vertical tube with some form of flow control to a horizontal viewpoint. Might be better for it to be circular, maybe a piece of plexiglass that could be curved into a tube.

I think I burned my brain out trying to fiugure the right way to spell plain (plane?) in this context.

regards
Mech

[freebeard]

I think I burned my brain out trying to fiugure the right way to spell plain (plane?) in this context.

You may be right.

According to To Predict Turbulence, Just Count the Puffs - Issue 15: Turbulence - Nautilus 'puffs' are an analog to the virtual quantum particles that presage quarks.

This suggests that a test section coated on the inside with some hydrophobic material might supress the puffs that lead to turbulence, reducing the necessary cross-section.