Does anybody have any leads to a decent (safe) smoke generator for a homebuilt wind tunnel?
Tried joss sticks but they stink the room out and don’t produce enough smoke. Wind tunnel is 6" square.
You could maybe try an ultrasonic mist generator? Never trued using it for a wind tunnel my self but could be a good smell-free alternative?
Dry ice.
As it sublinates it produces harmless vapour.
But it has hazardous properties to consider…
One might say Dangerous Goods!
But yes handle with care.
Dont lick.
But still safe enough.
Oh yes (in even relatively small quantities).
One of my aviation colleagues had some dry ice supplied to keep the posh catering cool. At the end of the flight, he wanted to get rid of the 2 small briquettes that were still remaining.
Easy peasy, dump them down the aircraft (liquid) toilet. BIG mistake - blue water volcano!! 
https://www.screwfix.com/p/arctic-products-smoke-pellets-5g-10-pcs/64647
You can get some from screw fix
“Burns for 30 seconds and produces 15m³ of smoke.”
That’s a LOT of smoke!!
Get a disco smoke machine? Or will that produce too much smoke?
Might give them a miss!
H302 Harmful if swallowedH317 May cause an allergic skin reaction.H319 Causes serious eye irritation.H335 May cause respiratory irritation.H400 Very toxic to aquatic life.H410 Very toxic to aquatic life with long lasting effects.EUH 401 To avoid risks to human health and the environment, comply with the instructions for use.
Precautionary Statements P102 Keep out of reach of children.P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.P260 Do not breathe dust/fume/gas/mist/vapours/spray.P273 Avoid release to the environment.P308 + P311 IF exposed or concerned: Call a POISON CENTRE/doctor/…
The average ultrasonic mister will not produce sufficient fog for a wind tunnel. Dry ice is a pain to store and, CO2 being heavier than air, is possibly not a great choice for a wind tunnel.
A small disco smoke machine is probably your best bet and can be had relatively cheaply these days.
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You can get cans of aerosol smoke testers for smoke alarms - but I don’t know if they spray smoke or just a mist. However, marked “highly inflammable.” 
Any miniature steam train (Hornby, etc), enthusiasts? You used to be able to get a liquid or pellets to give the smoke effect for the locos, but I guess that there is an internal heating element to generate the smoke.
Some (not cheap!) items from here.
A make your own design - uses a vape pen.
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A little blip now and then into a holding tank of some form would probably suffice.
A closed box would probably do, with the feed to the wind tunnel being taken through it.
50 m³/min sounds like a lot, but if you only run the machine for a couple of seconds as and when needed…
But the aerosols might be worth investigating.
Just seen this smoke solution (using a Vape (e-cigarette) pen) which I received via the Aerospace Testing web site.
https://www.youtube.com/watch?v=Sx5BQjKvElk&feature=emb_logo
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Niiiiiice.
Get the cadets addicted to nicotine at the same time as teaching aerodynamics.
Wake up in the back row! 
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