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smoke
There are commercial smoke generators.SAE published an entire book on imaging,including smoke and it might contain info on fabrication.I've glanced at it but don't own a copy.Texas Tech Aero Lab had a commercially produced smoke unit we used on a model in 1991.$1,100.00 US was the price at that time.A non-toxic oil is electrically heated and flashed off as smoke in a chamber exposed to the windtunnel airflow and flows to the rake,exiting at the exact velocity of the tunnel's flow,so as not to introduce turbulence right at the rake.------------- To do this on a moving car would require some fanagleing,as well as providing a sinewave inverter powerful enough to run the unit.---------------- You might cobble up a DC- powered unit to do the heating and experiment with a ram tube you could calibrate to match to the car's outer flow field.--------------- Demonstration parachute teams and aerobatic airplanes both do smoke.I think the parachutists use smoke bombs.They can be purchased at HVAC suppliers in sizes up to 50,000 cubic feet.The thing about them though,is that once you light them,they burn to conclusion----------------- I think the aerobatic planes spray oil onto the exhaust system.Don't know for sure.-------------- A bunch of us have settled on yarn tufts taped to the car for proof of flow.Darin has a boom which supports a video camera and he's self contained.I end up getting friends to drive "chase" cars and operate the camera to "freeze" the action.
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