A mathematical question

[micksmanlyjunior]

Hi all

I am making a very simple dust extraction unit.
I have a fairly powerful blower from one of those hand driers that are in all public toilet facilities. I have taken off the heating element etc and have come up with an idea on how to make it the powersource for an extraction unit.

However I am not sure how much power it will create.

I am planning on hooking up the blower to a 1" thick piece of flexi-pipe and then run that in through one side of a y-piece of plumbing pipe and have it continue approximately 3 inches past the juntion of the y-piece. This will force air down the one side of the junction creating suction in the other side.

Do you think that the suction created would be sufficient for basic sawdust.

I am planning on running some flexi-pipe from the exhaust side of the y junction directly into a sealed bin with a filter so the bin can vent excess air.

[micksmanlyjunior]

anyone who would like me to email them a picture of my design pls let me know your email and I will send it your way.

[Ron Williamson]

It depends on what you are trying to accomplish.If you are picking up sawdust from a tablesaw,it probably won't do much.If you are picking up sanding dust,then the Bernoulli effect might be helpful.
I have a 1hp dust collector on my downdraft sanding table,and while it does a great job of keeping the dust,some still flies around.
R

[Cedarhill Boatworks]

We used the same principle in the navy for dewatering. They were called eductors and used the flow of water from a firehose through a y fitting to produce suction. They worked great in a closed system to pump water, the ratio was close to 1:1, however that was water. I think with some fiddling with pipe sizes you may get some action but I fear you will be disappointed with the final results.

[Frank Wentzel]

Mick

Commercial dust extractors use motors in the range of one to two horsepower. The hand dryer specification plates that I have seen indicate that they have two amp motors - that is about 1/4 hp. Use of the Bernoulli effect, while it will increase the volume of air moved, will introduce further energy losses. I would guess the final result would be on the order of a 1/8 hp dust extractor. Sorry to rain on your parade. :(

/// Frank ///

[Ed Harrow]

Mick, I confess to not being able to envision the arrangement of the "Y", but I fear you will be sorely disappointed. Throughput is a 4th power function of the diameter of the pipe, and also related to the difference between inlet and exhaust pressure, and I fear that will be close to zero for your device.

Of course physicists have proven that the bumble bee is incapable of flight smile.gif

[micksmanlyjunior]

Oh well it was an attempt at saving a few bucks so I could spend more on my baby 12 footer.

Oh well, to try and track down an old vaccum setup

thanks all

[TomRobb]

I think the old bumble-bee thing was before anyone knew how insects operated their wings - not at all like an airplane wing - if I understand it more or less right, they sort of surf on rolling vortices off each previous wing sweep for a large increase in gross lift.
Knowledge in science works by sucessively more accurate aproximations of the Truth

[Ed Harrow]

Yup, like my orthodedist said, "We used to think but now we know." ;)

[Bruce Hooke]

A friend of mine actually studied bumblebee flight for a while. They had a setup where they could put the bee in an enclosed flying space (a tube) and actually measure how much air the bee was breathing as it flew vs. when it was still! It still amazes me when I think about this...the numbers involved are just so tiny...

I recently saw a re-broadcast of a great program on Paul McCready's work (the Gossamer Condor/Albatross guy) and he is apparently doing some explorations into tiny surveillance aircraft that fly like insects...

[htom]

It turns out that the aerophysicists can explain how bumblebees (and other insects) fly, once you realize that they're helicopters, not fixed-wing aircraft.

(Later details are that they're not helicopters, but some third thing that I forget the name of, but the helicopter equations work to explain that they can fly. Whether the USMC is investigating this mode of flight as a future replacement for the V-22 is probably classified.)