Flow visualization paint

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MX304
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Joined: Sun May 17, 2009 5:35 am

Flow visualization paint

Postby MX304 » Sun May 17, 2009 5:40 am

Do any of you know a US source for, or even better, a way to make the paint that the teams use to get airflow visualization?

flynfrog
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Re: Flow visualization paint

Postby flynfrog » Sun May 17, 2009 3:05 pm

do you mean the diesel and dye method. Or the actual pressure sensitive paint?

You can make the first one yourself not so sure on the second one.

MX304
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Re: Flow visualization paint

Postby MX304 » Sun May 17, 2009 3:35 pm

I don't need pressure sensitive, at least at this point.

riff_raff
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Re: Flow visualization paint

Postby riff_raff » Mon May 18, 2009 4:18 am

MX304,

For streamlines they used to use colored oil and matrices of yarn tufts on the track, which were videotaped. In the tunnel they use smoke wands, and sometimes even tools like laser velocimetry for very detailed studies. The tunnel models also have lots of little holes in their surface which are connected to very sensitive pressure transducers, from which the dynamic surface pressures can be measured.

But as for actual flow visualization, I don't know of any paint that will give you that feedback. There are types of pressure sensitive coatings that can be applied, but they require careful calibration and special cameras to get results. And they will only give you surface pressure distribution, not flow data.

CFD softwares are now widely available, fairly easy to use, and can give very good results when used properly. Most aero work is now performed digitally, with tunnel work only being used to validate the analytical modelling.

Here's a source for pressure sensitive paints and films:
http://www.innssi.com/PSP_Products.html

Good luck,
Terry
"Q: How do you make a small fortune in racing?
A: Start with a large one!"

benjabulle
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Re: Flow visualization paint

Postby benjabulle » Sun Sep 05, 2010 9:53 pm

flynfrog wrote:do you mean the diesel and dye method. Or the actual pressure sensitive paint?

You can make the first one yourself not so sure on the second one.


I'm interested in this one for vizualization on a slot car, can you explain more ?

marcush.
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Joined: Tue Mar 09, 2004 3:55 pm

Re: Flow visualization paint

Postby marcush. » Sun Sep 05, 2010 10:27 pm

I think some guys use WD40 and just rely on dust being attracted to it this shows nice traces and the wd 40 is thin enough to flow also in areas were not much is happening..

benjabulle
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Re: Flow visualization paint

Postby benjabulle » Sun Sep 05, 2010 10:33 pm

ok, why not, I'll try it.

marcush.
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Re: Flow visualization paint

Postby marcush. » Mon Sep 06, 2010 11:04 am

as I understand flowviz constitutes of kerosene and a fluorescent powder mix(dye) the kerosene evaporates and leaves the powder traces on the area of interest.
possibly some oleic acid to prevent the mix from coagulating..

polarboy
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Joined: Fri Dec 04, 2009 12:09 am

Re: Flow visualization paint

Postby polarboy » Wed Sep 08, 2010 10:10 am

Lots of the aero guys look round the cars after a wet race you get VERY good results from dirty water in a real race situation

mx_tifoso
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Re: Flow visualization paint

Postby mx_tifoso » Sun Sep 12, 2010 7:54 am

It's runnier than I imagined it to be.

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raymondu999
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Re: Flow visualization paint

Postby raymondu999 » Sun Sep 12, 2010 10:07 am

Indeed. I wonder how the teams can get much use out of such a runny fluid. I would've thought something more viscous would've fit the bill better
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mep
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Re: Flow visualization paint

Postby mep » Sun Sep 12, 2010 11:39 am

Might they have put to much on it?
Looks like they have to analyze the paint right after the run because it looks like the down flowing paint destroys the streamlines picture.


Regarding flowvisualisation in home use you could also use this stuff:

http://www.feuerwerk-sauer.de/sortiment/rauchkl.htm
Sorry I don't have an English link.

I used them once. I took the big cartridges cut them into pieces and took out the powder (not allowed here but who cares). With the powder you can adjust the amount of smoke you want better. Just lit it and you have colored smoke.
The small particles in the smoke will then deposit on the surrounding environment giving you a similar effect than the flowviz fluid. Just don’t inhale it and don't use the white smoke it doesn't give you a good contrast. When you make a video of your experiment white smoke is hard to spot. I got good my best videos by using a stroboscope.
http://en.wikipedia.org/wiki/Stroboscope
Important is that the light comes from in the same direction in which you record the experiment on video.

After used once you might wash the small particles of and collect them somehow to make real flowviz fluid. I have not done this yet.

marcush.
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Re: Flow visualization paint

Postby marcush. » Sun Sep 12, 2010 11:43 am

raymondu999 wrote:Indeed. I wonder how the teams can get much use out of such a runny fluid. I would've thought something more viscous would've fit the bill better



I think they really have to learn how much to apply... :mrgreen: much helps much.But for sure this is a very good thing to do in installation laps to see if everything is attached as it schould in terms of covers etc..especially with that weak pretend engine they yhave to use...

Peter-RC
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Re: Flow visualization paint

Postby Peter-RC » Tue Sep 14, 2010 8:10 am

marcush. wrote:I think some guys use WD40 and just rely on dust being attracted to it this shows nice traces and the wd 40 is thin enough to flow also in areas were not much is happening..

that's a good one, i'll try it this weekend with my 1:8 car.




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