Quote:
Originally Posted by aerohead
*If you do a closed test section,the models projected frontal area should be no more than 5% of the tunnels test section cross sectional area.This prevents the walls from effecting streamlines.
* I'm not current on smoke generator state of the art but in past times,an oil like SHELL Ondina was electrically heated within a metal wool,flashing off as a cloud of smoke into a vessel which was in series with the tunnel.Air from the tunnel enters the vessel at test section speed,picks up the smoke and enters the smoke wand or smoke rake,discharging into the section airstream at an equivalent velocity so as not to create its own turbulence.
*As of 1991, commercial smoke generators started at around $1,100 (US).
*Your fan(s) will need to develop a volume of air equal to your test section velocity (80-mph) multiplied by the section area ( 100 sq ft ),or,704,000 CFM.
*A local HVAC company could help you with static pressure requirements,friction losses and necessary horsepower to drive it all.
*And if you do measurements you'll need to construct a 3-component balance.Texas Tech used the 'sting' from a military aircraft.It has strain load cells of 3-axis.$68,000.
* Alan Pope has a fine book on low speed wind tunnel design.
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Phil is right no doubt. (Since I recently had the privilege of meeting him, which was so worth the effort, I'm more convinced than ever.) All the experts fixate on Re and it makes perfect sense. That said, the Wright Brothers' wind tunnel produced extremely useful data. Also, considering orders of magnitude between jumbo jets and tiny insects, Re scaling does not seem to prevent flight. That leaves me to hope that, while scale wind tunnel testing without full Re compensation might not be perfect, it may be good enough to compare some shape effects. That could make me the most naive person on the planet for all I know (but I can also think of worse problems - wink).