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Fan for bernoulli science demos?

Fan for bernoulli science demos?

Fan for bernoulli science demos?

Hello colleagues,
I am a veh. dynamics engr. with a question which is out of my field. Our local section of ASME (western suburbs of Chicago) has shown off Bernoulli principals to middle schoolers for years, and we are looking to improve our air supply. The demos include a "windstorm" lifting a roof section of a small model home, blowing between two hanging pingpong balls to bring them together, blowing between two foam 12" dia. disks such that they cannot be separated, and levitating a pingpong ball in an airstream. The first two are done with handheld blowdryers. The final two are with a shopvac set to blow.

All these make considerable noise and make it tough to explain at a science expo where there is already much ambient noise. We usually have 3-4 members doing these simultaneously at a 8' long table.

I'd like to replace the various air supplies with a blower in a plenum, with several holes available at the top where we could plug in multiple vacuum cleaner hoses -- one per demo. And I'd like the blower to operate continuously--thus something rated for intermittent use is not optimal). I believe with a sturdy 3/4" (seams sealed) plywood box for the plenum, a low-pressure labyrinth inlet and some open-cell foam as lining, I can quiet the supply considerably.

HERE's the question for aerodynamicists and/or HVAC types:
What kind of blower would you suggest? (axial, squirrel cage, gutted leaf blower or other device?) If performance is not good enough, do I achieve anything with such blowers in parallel or series?

Thanks for any advice.
Bill S., PE
ASME Fox Valley Section

RE: Fan for bernoulli science demos?

The cheap and portable ones will all be loud - how about putting the blower outside the room, and running some hose back inside to your plenum?

RE: Fan for bernoulli science demos?

shop vac's aren't That noisy ... but certainly enough to interfere with discussion ... talk first, then demonstrate, then follow-up ("what did we see ?", ppt ??)

positioing the airsupply at a distance and duct the air in (dryer outlet ducting ?) ?

btw (just 'cause i'm a cranky olde fart) ... it's principLE

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