DIY wind tunnels

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Originally Posted by aerohead

All the serious scientific work is done in a tank,with the gantry riding rails on either side moving the model through the water.
The U.S.NAVY's David Taylor Model Basin is probably the most famous.
Texas Tech constructed a smaller tank setup to test a 1/3-scale ( I think) Ford Taurus model with complete engine compartment and clear hood to photograph under hood cooling flow.That model cost $63,000.
Somewhere I have a SAE Paper of tests on 1/24-scale F-1 or Indycar models that were pulled underwater.I'll see if I can find it.
Texas Tech has a water tunnel in which dye (red food coloring) is released from ports drilled in the models body,which can be observed through the glass test section.No force measurements can be obtained.
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I did find GM's Paper.
It's from SAE Transactions,Volume 70,1962.The research was conducted at Cal Tech,in the Guggenheim Aeronautical Laboratory by Harold Flynn and Peter Kyropoulos,using 1/8-scale models.
The model was @ 4% test section blockage ratio,Rn=17,000,000,@ 160 mph wind velocity,with a 600-hp blower.
There is a pictorial representation of their data which I put together over at the trailer thread.
Their work seems to verify the 'Denominator-Rule' if you will,where in order to achieve proper boundary layer verisimilitude,you merely multiply 20-mph times the denominator of the fraction which defines the model scale.
i.e.GM's 1/8-scale = 8X20= 160 mph.

I am liking the sound of the water test tank, I can make a test tank in the back yard no problem. Setting up the gantry would take more time.. a simple one should not be that difficult (I say that now)

For a wind tunnel I would need a 1280mph wind for the 1/32 model or a 720mph wind speed for a 1/18.

I have one of those large leaf blower / shop vac crosses with a 3" hose that I can test the car with its easy enough with no need for a enclosure. When my wind gauge gets here i will check the speed. I am not sure if smoke will show up at those winds speeds ? edit: sheet my wind gauge maxes out at 65mph, thats no good..

Now I want the water tank

Here is a great pdf from a Students thesis on scale wind tunnel
http://www.davidoprevatt.com/wp-cont...ors-thesis.pdf

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Some interesting tests can be done with small scale , once a base line is measured you can modify and measure for changes, positive or negative.

https://www.youtube.com/watch?v=Cu0uNPFCf68