1:24 water tunnel for flow visualization

[Vekke]

I just started to fabricate my own water tunnel. Plan is to make the tunnel so big that you can test 1:24 truck.

Truck main dimensions are 100mm (W) x 150mm (H) Tunnel dimensions will be 5x those -->500x750mm.

Trucks length is about 700mm
What is enough length for this tunnel?
Is that turn too tigth?

DIY Water tunnel.jpg - Windows Live

All pictures, datasheets and videos of working water tunnels are welcome. There will be huge acryl window to see the test sections flow properly

[Vekke]

That straight section is 1260mm long at the moment. That is enough for small car but is it enough for truck and trailer which was that 700mm long? Project will continue on wednesday .
http://cid-acb1f13bac776768.photos.l...comparison.jpg

[euromodder]

How high is the water going to be in the tunnel ?

If you're going to fill it up to anywhere near the height of these side boards, the seams are going to pop unless you SERIOUSLY strengthen them.
Some nails or screws and glue ain't gonna do the job.

Look into angled steel reinforcement at the bottom corners, with steel straps keeping the tops properly spaced.

[Vekke]

750mm high if the truck is on testing. I will add glasfibre layers inside and also put more streghtening ribs where I think it will need them.

[euromodder]

A friend of mine has built a temporary 2.5 m3 wooden fish tank to relocate his fish.
He's the kind who'd rather put in an extra nail, but despite looking pretty sturdy to me, it's already coming apart at the seams.

[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 :/.

http://www.youtube.com/watch?v=L0ki-FtPYrA

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

time=priceless .

[andylaurence]

An off-the-wall suggestion here, but what about using water flow from a river in a water tunnel? It's an endless supply of fast moving water. Use a small stream and it'll be steeper (easier to get onto the bank) and cleaner.

[euromodder]

Originally Posted by Vekke

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

Speed control should be fine with an electric motor

In the film the water is flowing rather slowly when you see the flow tank - until the aero shapes are shown, then the flow is faster, though I think these are sped up after recording.

Wouldn't the Reynolds number combined with the viscosity determine your water flow speed range ?

[aerohead]

Vekke,did you happen to catch the Myth-Busters episode in which they tested pickups for tailgate up/down fuel economy?
In that episode they constructed a simple 'atmospheric' open-top water tunnel which looked akin to a horse race track.
A 24-VDC electric trolling motor was used to move the water.
A clear Plex window allowed viewing of the model pickup as the water flowed by.
And they simply put something like breakfast cereal in the water to reveal what the flow was doing in proximity to the model.
With the grain in the water you could clearly discern the open pickup truck bed 3-D vorticity as is depicted in CFD images.
Dirt simple technology!

[Vekke]

MetroMPG has posted the video here:

http://ecomodder.com/forum/showthrea...html#post13237

My current tank is looking 90% same. They didint have any vanes at the end of the tank and flow was turbulent. I will anyway build this tank ready and try get the flow under control.