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Member

Join Date: May 2007
Posts: 8

Wind tunnel smoke

05/20/2007 10:25 AM

Greetings

Could anyone tell me where to find or how to make smoke to utilize in wind tunnels for aerodynamic tests, type of a needle stream?

Thanks a lot in advance

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Pathfinder Tags: smoke for aerodynamics tests
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Associate

Join Date: Apr 2007
Location: Newcastle - NSW - Australia
Posts: 26
Good Answers: 1
#1

Re: Wind tunnel smoke

05/21/2007 2:21 AM

Hi LdV,

I would also like to know what the big boys use ??

I have built a 3.5 metre long wind tunnel in the garage and have been using a high speed camera at 125 frames per second to observe a 1:10 scale - wind turbine, I am designing.

I have used dry ice in warm water, and because it is heavier than air, I quickly found the couple of trays in the tunnel run out in a second or two, at a wind speed of 2 m/sec.

I am building a reservoir to fill and then flood the entry, somewhere about 2-3 metres cubed, like a tower, with a knife gate valve at the bottom ...........

This can then be dumped when the wind tunnel and turbine are at the required speeds for observation.

I hope somebody can enlighten us all with "The GOOD smoke" .....

Regards,

Macker

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Power-User

Join Date: Mar 2007
Posts: 285
Good Answers: 6
#2

Re: Wind tunnel smoke

05/21/2007 3:39 AM

One homebrew device (that works...) is fixing 2 hypodermic needles so that their points are close together and slowly piping into them small quantities of ammonia gas through one and hydrochloric acid gas through the second. Although both gases are poisonous the result of the reaction between them is ammonium chloride which is a relatively inoccuous white solid. What you get is a thin stream of white 'smoke'. Arranging a row of such devices alows you to see and photograph aerodynamic stream lines. Beware of the toxicity and find out about the relative gas flows needed so that you can properly make the adjustments.

Some manufacturers used to sell small 'puffers' which made little white clouds that you could follow. I haven't seen them around for some time.

Google and enjoy.

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Guru
United Kingdom - Member - Olde Member!! Engineering Fields - Instrumentation Engineering - New Member

Join Date: Jul 2006
Location: Dunstable, England
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Good Answers: 44
#3

Re: Wind tunnel smoke

05/21/2007 6:57 AM

What do they use in those smoke machines used in discos / parties etc...?

That must be pretty innocuous to use in a public place...

I know the smoke machines are filled with a liquid which is heated when smoke is needed...

John.

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Anonymous Poster
#4
In reply to #3

Re: Wind tunnel smoke

05/21/2007 7:55 AM

Hey all.

Commercial "fog machines" use a mixture of propelyne glycol glycerine and water. Roscoe makes a very good one. We use the term Fog machine and not smoke in the industry because these macines are not actually burning anything. The trick is to make your "needle stream" because compressing the fog stream (actually tiny drops of water and glycerine) tends to make the fog sublimate back out. Leave an air gap between the nozzle of the machien and the tube to crudely venuri the vapor through the tube will help. I don't know how thin a stream you need.

A small steram generator might work too.

Have fun with it.

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Member

Join Date: May 2007
Posts: 8
#5
In reply to #4

Re: Wind tunnel smoke

05/21/2007 8:13 AM

Dear all

Thank you for your info which was very usefull.

I also found a site windsolutions .com that has affordable small machines with inocuous fluid.

Also one can make smoke by mixing sugar and salpetre and baking soda as a retarder.

It is easy but needs care when heating the mixture slowly so that it does not self ignite. The problem is how to dose it for wind tunnel needle aplications.

Regards

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Anonymous Poster
#6
In reply to #5

Re: Wind tunnel smoke

05/21/2007 11:33 AM

I seem to remember that wind tunnel testing used to use Titanium Tetra chloride to generate smoke.

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Anonymous Poster
#7
In reply to #6

Re: Wind tunnel smoke

05/21/2007 5:42 PM

Ya. - But this is not something for the kindergarten set to play with.

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Guru

Join Date: Nov 2006
Location: KnoxTN
Posts: 1499
Good Answers: 6
#8
In reply to #5

Re: Wind tunnel smoke

05/21/2007 7:38 PM

Tear gas makes a pretty white smoke too!

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Guru
United Kingdom - Member - Olde Member!! Engineering Fields - Instrumentation Engineering - New Member

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Good Answers: 44
#9
In reply to #8

Re: Wind tunnel smoke

05/22/2007 7:17 AM

Hmmmm I seem to remember from school days that mixing bleach (sodium hypochlorite?) with brake fluid (hydroscopic) produced large quantities of a smoke like substance...

Don't know how dangerous the smoke is though...

John.

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Anonymous Poster
#14
In reply to #4

Re: Wind tunnel smoke

12/23/2008 10:35 PM

thanks for the idea but i want to know this is dengerous to do? and i don't know how does "propelyne glycol glycerine" look like.

thank you

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Anonymous Poster
#10

Re: Wind tunnel smoke

05/24/2007 1:05 PM

Try www.kanomax-usa.com & download their catalog. They have a smoke generator for wind tunnel testing, as well as a distribution header (to get the nicely spaced streams).

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Anonymous Poster
#11
In reply to #10

Re: Wind tunnel smoke

02/15/2008 10:16 AM

for a small scale wind tunnel (around 5 inch diameter) I used two funnels (one either end of a central clear pipe) and a stack of drinking straws (cut into 3 to increase the ammount and reduce the length). Then popped a smoke pellet in the pouring end of one funnel and a vacuum cleaner hose on the end of the other. The straws straighten out the ariflow and the smoke pellet provides plenty of smoke (for around 45 seconds). Moving the vacuum hose forward and backwards in relation to the funnel gave a harder or slower pull - enabling me to change the airspeed.

Basic diagram here: http://www.crowcrow.com/image/wind_tunnel.jpg

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Anonymous Poster
#12
In reply to #11

Re: Wind tunnel smoke

04/07/2008 1:26 PM

Where does one find the smoke pellet? My son is trying to build a wind tunnel to test model car aerodynamics.

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Guru

Join Date: Feb 2008
Location: Van Nuys, CA
Posts: 562
Good Answers: 31
#13

Re: Wind tunnel smoke

04/07/2008 2:34 PM

I haven't tried these, but they might work...

Smoke emitters for HVAC testing
http://www.hvactool.com

Smoke emitters for radio controlled aircraft demonstrations
http://www.regin.com/rcsmoke.html

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Anonymous Poster
#15

Re: Wind tunnel smoke

01/25/2009 11:53 AM

You can use poly glycol, Its used in all kinds of foods. I made a smoke machine for work using a small space heater, a gas tank from a lawn mower. With a coil and a little air pressure it makes quite a bit of smoke. We have another one that uses electricity to heat the fluid in a wand and do pin point tests.

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Anonymous Poster
#16

Re: Wind tunnel smoke

04/23/2009 6:41 PM

You can buy cans of fake smoke at most hardwhare stores. They are normally used for testing smoke detectors. Good luck!

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Anonymous Poster
#17

Re: Wind tunnel smoke

05/20/2009 10:49 PM

I used to work in the tunnels at NASA. Find Lenord Weinstein's paper on smoke wands in the NASA database. It is cheap and will give you great smoke. I teach now at WVU. email me if you need help. pgall@mail.wvu.edu

Pete Gall

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Participant

Join Date: Jun 2008
Posts: 2
#18
In reply to #17

Re: Wind tunnel smoke

01/26/2010 12:07 PM

Pete,

How about a link to Leonard Weinstein's paper?

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Anonymous Poster
#19
In reply to #18

Re: Wind tunnel smoke

04/12/2010 12:12 PM
All,

Note, this is the latest paper on the subject. You can find it through ntrs.nasa.gov/search

Pete

Vapor-Generator Wand Helps To Reveal Airflow Patterns

Author(s):

Robelen, David B.

Abstract:In vapor-generator wand, liquid propylene glycol flows into electrically heated stainless-steel tube. Liquid boils in heated tube, and emerging vapor forms dense, smoke-like fog used to make airflow patterns visible. Built in variety of sizes, suitable for uses ranging from tabletop demonstrations to research in wind tunnels. For best viewing, plume illuminated by bright, focused incandescent spotlight at right angle to viewing direction. Viewing further enhanced by coating walls of test chamber with flat, dark color to minimize reflections and increase contrast.
NASA Center:Langley Research Center
Publication Date:Dec 1, 1993
Document Source:National Technology Transfer Center (NTTC), Wheeling, WV
No Digital Version Available:

Go to Tips On Ordering

Available Data:Additional information available through: National Technology Transfer Center (NTTC), Wheeling, WV 26003, (Tel: 1-800-678-6882).
Document ID:19930000764
Accession ID:93B10764
Publication Information:NASA Tech Briefs, 17, 12, P. 53, ISSN 0145-319X
Report Number:LAR-15058
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Participant

Join Date: May 2011
Posts: 2
#22
In reply to #18

Re: Wind tunnel smoke

05/04/2011 5:42 AM

http://www.freepatentsonline.com/4493211.pdf

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Participant

Join Date: May 2011
Posts: 2
#23
In reply to #17

Re: Wind tunnel smoke

05/05/2011 5:08 PM

Hi Pete I made a smoke generator for my low speed wind tunnel, similar to NASA' smoke generator (Robelen) , and UNIVERSITY OF WASHINGTON's. But I can t achieve good result. Problem is how to inject smoke into tunnel? Please help me. what is your e mail?

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Anonymous Poster
#20

Re: Wind tunnel smoke

10/10/2010 7:31 PM

http://www.aa.washington.edu/uwal/download/documents/smokegen.pdf

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Member

Join Date: Nov 2010
Location: Thunder Bay, Ontario, Canada,
Posts: 7
Good Answers: 2
#21

Re: Wind tunnel smoke

11/10/2010 10:44 AM

The very best, and lowest cost thing is a fog machine they use for stage shows. Eliminator EF-400 Fog Machine on EBay. It costs about $30. Hook up a hose to it and spew a stready stream of fog where you want. It works awesome.

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Anonymous Poster (12); b_kohlenberg (1); chocolater (2); dovy (1); Electroman (2); Leonardo da Vinci (1); Macker (1); pantaz (1); philponkamecheng (1); Stirling Stan (1)

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