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simple turbine design

simple turbine design

simple turbine design

(OP)
I wish to spin up a disk 100mm to 20,000+ RPM for a test rig. At the moment I can get around 16,000 rpm with a compressed air nozzle and simple turbine. Any advice on turbine/nozzle configuration in order to optimize design.

RE: simple turbine design

Two nozzles?

Mike Halloran
Pembroke Pines, FL, USA

RE: simple turbine design

I seem to recall from way back when that woodworking routers will hit 20,000-30,000 rpm- would that work instead?

RE: simple turbine design

I'm sure you thought of this but I'll throw it out there. Have you tried a supersonic nozzle (converging / diverging)?

RE: simple turbine design

(OP)
Supersonic nozzle sounds interesting. Where would I find such a thing. No luck on Google and foxvalve not suitable. thanks

RE: simple turbine design

Without a sonic nozzle you cannot exceed the choked flow velocity.  You can pull a perfect vacuum and have infinite compressed air pressure and you will still not exceed Mach 1.

I don't know where to buy such a nozzle.  I know small ones exist because we used them in wind tunnel testing.  Maybe a laboratory equipment supply catalog?

RE: simple turbine design

I would encourage you to calculate the windage drag on the 10-cm disk, and from that determine the horsepower you will require.  See the following link:

http://ntrs.nasa.gov/search.jsp?R=373856&id=2&qs=Ntt%3Ddrag%252Brotating%252Bdisk%26Ntk%3Dall%26Ntx%3Dmode%2520matchall%26N%3D0%26Ns%3DHarvestDate%257c1

As Jstephen suggested, an air-driven router may be a good item to purchase, and disassemble to learn something about how to make a high-speed turbine.  Forget supersonic nozzles, or any nozzle for that matter; you want to harness the expansion of the air to produce torque at very high rpm: you will need to make an axial-flow turbine, or possibly a mixed (axial/radial) turbine.

A quick back-of-the-envelope calc. using the moment coefficients from the above paper suggests that you might get a 1/4-hp air or electric router to spin the disk to 20k rpm in air.  Balancing the disk for that speed, and keeping everything intact may be a problem.  Suggest you watch this test from a distance, and keep yourself and anything/body else out of the "plane of rotation".  Better, do it like the pros (barbour stockwell) and put it in a pit or stack concrete blocks around it.

RE: simple turbine design

how about googling a "Tesla Turbine" or is that what you are trying to build?

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