Sound Proof Enclosure To Contain A 120Db Banshee

Why not just keep the soundproof test cell around it?

There's a hole in the bucket, dear Liza....

If it is making that much noise, it's inefficient. I.e. improve the efficiency and the noise problem self-solves.

Thanks for the comments, but all I am looking for is suggestions on how to build a sound reducing box around the device. I hope an accoustic engineer can provide some suggestions.

There are dozens of off the shelf acoustic damping materials - starting at lead through to foam (of various flammabilities and degree of noxious)

What is not clear is what frequency range and what is making the noise.

For instance; is it vibration of the blower, drive, etc, 'drumming the steel table?

Is it purely intake noise? or output noise?

Second tier is what aspiration volume, if any, is required.

Third, what of heat due to compression, or friction?

Fourth, do you need to see the thing?

Answer those and perhaps an acoustic engineer would have a chance at making a useful suggestion.

For instance; if you levitate it in a perfect vacuum, I guarantee it will be totally silent.

Though how that 'enclosure solution' effects your testing, is possibly worth a small ponder.

First of all what size/type blower are you using and how fast are you spinning it? Too much noise is generated when there is something mechanically wrong with the blower, or the blower is spinning way beyond it's rated RPM. If the noise is coming from the drive system and not the blower you need to examine the alignment and tension on/of the driving system.

Record the noise and play it back through speakers aimed at the blower and and alter the pitch until you get wave cancellation. beware! you can easily find a harmonic and double the level.

Unless you want to try to duplicate some of the esoteric methods that are coming out of bleeding edge research your best bet is mass, the more the better. Clearly it has tradeoffs. Want to be able to see it? How about some nice 1" thick glass? How about bricks, they're cheap. You can put all the foam you want but it isn't going to be a substitute for mass.

I think I'd start with a simple box constructed out of some cheap 2x2 vinyl coated steel wire fencing material. Stuff comes in rolls you buy at Home Depot or Loews. Cuts wit simple wire cutting pliers and fasten at the corners with twisted wire. Then go to Costco or Walmart and see if you can buy one of those visco-foam mattress toppers for material to line the outside of the wire mesh box (plan on using lots of duct tape).

If that material doesn't appeal to you try some 2" thick polyisocyuranate rigid insulation foam (foil coated preferably) that comes in 4x8 sheets at some professional lumber/building supply companies. (provide local building codes allow it). Cuts easy with any kind of saw; but try not to breath the dust. Fasten to the wire cage with tie wraps and duct tape. Isolate and seal the enclosure to the machine mounting base with same or similar foam.

This will tell you how much of the noise is being transmitted directly from the blower structure to the air. There are other paths to consider of course.

A baffle muffler?

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Aerofoam gels

banshee

Good links; I liked this;

"A proposal to increase the aircraft's speed by adding afterburners was canceled after a test aircraft suffered extensive damage to the wing roots and tail structure when the afterburners were actuated"

found here

Beefburger, Thanks this is the sort of practical advice I was looking for.

Can you tell us what the frequency is? Do you have an analyzer, or a Db meter?

Lead comes to mind, with the minuscule information provided.

if the the blower is adjusted correctly, the rotor noise should be drowned out by the velocity of the incoming air. i would'nt stand with in a 100' of it. instead of designing a sound proof enclosure, i would suggest wrapping it in a kevlsar blanket. the rotors have low tolerances and very few people have the experience to be able the adjust them correctly.

The original question does not hang together. I used doing maintenance on my old V8 driven car, with the hood up, my head stuck under the hood. No problem, no screaming even when revving up.

If it is screaming for you, it is vibrating like crazy, from brutal overdrive. It will fail, soon. The fatigue cracks growing will let it blow up like small bomb. The fan is heavy gauge steel. An enclosure will not contain it, when it decides to fly. Not a healthy environment to be in.

What is the point? Exhaust and blower can be had off-the-shelf for a reasonable price, with engineering done right.