Homemade wind tunnel?
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Why couldn't you use a peanut oil fog machine and a big fan for home wind tunnel testing?
Note: Wind tunnel assistant not included. |
justpassntime -
Would you have to "scale" the wind speed to the scale of the model or ?!?!?!? CarloSW2 |
I wish I had the space to build a full size one. Maybe build like a small steel building in the backyard of some future house and put a fan that could simulate 60mph winds on my actual car or something...
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My dad actually has a 5 foot (blade) diameter fan that can sustain 35 mph wind. Runs on a 2hp electric motor; barley starts on a 4kw generator but man is it nice when working outside. Hmmm
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I've thought about building a scale model wind tunnel. Just can't seem to find a model of the Jeep Cherokee.
A good example of a scale model wind tunnel setup can be found here. |
Try the toy section...
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Check this out VINTAGE METAL TONKA JEEP CHEROKEE WAGONEER TOY TRUCK - eBay (item 140245515768 end time Jul-06-08 18:21:57 PDT) |
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Do want wind tunnel or data?
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I know alot of you are DIY'ers, has anyone thought of retro fitting a spray booth as a wind tunnel? Or is it to small?
That would seem logical, plus you get the added benefit of being able to paint in it, if you maintain it properly. |
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spray booth
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According to my calculations, based on stuff I just looked up all over the internet, if 20mph air at 1:1 scale is enough to observe the relevant turbulence, 30mph water will work at 1:18 scale; a scale at which models of most of our cars are widely and cheaply available. That takes like 40,000gph at a 6 inch by 6 inch cross section, so a pump would be pretty expensive. A powerboat would probably be cheaper, although whatever cord you dragged your model by and the boat's wake would keep the water pretty turbulent.
But if you could hoist a lot of water 30 feet in the air, and get a few seconds of flow at the correct speed at ground level--assuming you could keep the flow laminar and drag-free--you'd have the correct ratio. The challenge, then, would be keeping the model from being immediately pulverized. We don't have any waterfalls here in Florida, because we don't have any elevation changes. Does anybody who lives near one wanna give this a try? |
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water
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A model can be drilled and tapped with dye outlets for food coloring joined to a common reservoir outside the tunnel.The colorant ejection velocity must be matched to the flow velocity to prevent a jet.Once calibrated,selective ports can be selected for release and observing/photography.When the water becomes saturated with colorant,chlorine bleach is injected to clear up the water. ------------------------------------------------------------------------- An underwater tow tank can also be constructed in which models are towed underwater from a traveling overhead crane ( as at the US NAVY David Taylor Tow Basin in Maryland) .Dye injection and tufts can be used for flow imaging. |
Thanks, aerohead! I thought the relevant figure for the Reynolds Number was the viscosity, 13x that of air. If we can really move the water 833x slower than air for a model of the same size, that's great.
My thought was to ignore the flow imaging and just do a/b testing: Put a scale on the tow rope and see how much drag I get on my car model (or any similar bluff body). Then put on miniature turbolator tape in various locations and see if the scale registers a lighter reading for the same water speed. Then, rig up a waterproof stepper motor to a spoiler and maybe a pump to test the devices in this crazy-looking Chrysler patent: Motor vehicle with flow-influencing devices to reduce air resistance - US Patent 6378932 Description |
Rn
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Which is easier way to get nice visual results towing the car vs flowing water? I would guess towing but how long do you have to make the tank to get nice flow and are the rotating wheels valid due to reynolds number?
If I want to get reasults for 1:24 truck for speed 50 mph do I tow the truck 50mph/833=0.06 mph (50mph*24)/833=1.44 mph or something else?. If I build flowing water tank is this good design like here on the this video or is it better to have only one flowing channel vs two returns? http://www.youtube.com/watch?v=L0ki-FtPYrA |
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