Possibility for a 2.5" scale dynamo

[Soot n' Cinders]

Alright guys, time to tell me how crazy I am!
Looking around online I stumbled across a 15w generator meant for a small wind turbine and wondered if it would also work for a small turbo generator. No load voltage is 12v at 1000rpm, but it can sustain 12v at 15w with higher RPMs, the spec sheet says maximum power is reached around 3000rpm.
Here is the link to the motor on Amazon: https://www.amazon.com/Cutting-Edge-Pow ... 311&sr=8-3

My plan would be to make a vane motor either using a home made vane or using a gear wheel. This would be attack to the motor and fed with a 3/16" steam line with at least 90 degrees between the nozzle and the exhaust, although I would like to try 270 degrees with the nozzle on an angle coming in like a prototype dynamo. Id then make a decorative housing for the generator and ground one pole to the chassis. The other pole would be run back to the cab to power 2-3 always on cab and sight glass lights and the headlight would be on a dimmer toggle switch. These lights would be 12v 2.4w flashlight bulbs.

So thoughts?

[Greg_Lewis]

I've been working on some dynamo castings for 1-1/2 scale and have decided not to make it function. The folks I've talked to say that a working gen. makes lots of annoying noise and the exhaust will come right back in your face. One friend made a working gen but doesn't use it for these reasons. I'll run a steam line to mine so I can turn it on from time to time for looks but there will be no innards.

[Glenn Brooks]

For 25 bucks you can’t go wrong! Buy it and see what happens...

My guess is you won’t need a huge amount of steam to make this motor work. The led’s might work with just a wisp of steam turning the motor, less than 12 v perhaps. Start small and experiment, maybe with one or two 1/8” nozzles. You could have three phase with three tiny jets! Maybe run the exhaust steam back into the boiler and reuse it... all kinds of possibilities.

[Fred_V]

The generators used in the hobby turn up to 10K RPM and would sling out the windings on that unit you are looking at. What seems to work is an alternator where the magnets spin and field windings are around the outside. Some years ago Live Steam had an article about making a 2.5" scale gen. Maybe 20 years ago. He used a fluorescent light ballast to get the plates and wound the field around them.

[Greg_Lewis]

For 25 bucks you can’t go wrong! Buy it and see what happens...

...

A valid point. Proove us naysayers wrong!

[FLSTEAM]

I agree with Fred. I have a turbine blade from a model jet engine and when I hit it with my shop air It easily spins up to 10,000 rpm. In fact it is scary to hold the shaft I spin it on.

John B.

[Greg_Lewis]

I agree with Fred. I have a turbine blade from a model jet engine and when I hit it with my shop air It easily spins up to 10,000 rpm. In fact it is scary to hold the shaft I spin it on.

John B.

OTOH, it would seem that you could make a turbine that is "inefficient" and would not spin that fast.

[Soot n' Cinders]

I figured I may give it a shot since the generator is only $25. Would have to see if 3000rpm is fast enough to generate enough torque to make 15w of electricity.
And just to be clear, I wouldnt use a true turbine blade. Too difficult to make. What I would use is a paddle wheel turbine, or a vane motor. Better low torque performance and doesnt spin as fast as a true turbine, but they are not nearly as efficient. Ive got a bunch of scrap around here I cold probably make a test turbine from.

[Greg_Lewis]

Please keep us posted — how about a build diary?

[Soot n' Cinders]

Please keep us posted — how about a build diary?

I will if I venture into this. Running out of free time at the moment.

[ALCOSTEAM]

I don't think it would be all that difficult to arrange for a 10 to 1 or even better gear ratio to get your impeller up to a better speed and keep the motor down in a safe range of operation. Most likely one would have to make their own gears. I have had this type of project on my mind for a number of years. Let us know how your project is coming along.

[Asteamhead]

Hallo Soot n' Cinders,

Your idea using a simple gear wheel instead of a sophisticated turbine blade wheel to me seems o.k.! Makes just a small difference using the same nozzle. Choose a wheel made of aluminium of the biggest diameter fitting into your housing.
That cheap DC-motor of your choice is another story, yet. Higher rpm means increased power out of the same amout of steam . Thus a minimum of 3,000 rpm is recommended. Yes, 12 W / 1 A may be realistic.
That motor wouldn't endure the 100°C temperature of the turbine's exaust steam. Total separation between generator and turbine by means of a coupling could solve that problem.
But as recommended before, a brushless motor with stainless ball bearings (innrunner) would match a lot better. I know (much more $)!
A steam nozzle of 1/16 " should do. Please first have a trial using compressed air to see, if your motor with the wheel on will deliver the needed current. Be careful regarding the no load speed, which may be much higher than 10,000 rpm!
To build at 2.5 scale will be a lot easier than at scale 1 or 1.5 due to increased size, believe me.
I built several working turbo generators over the last 30 years which worked on steam for hundreds of hours.
Thus my two cents here.

Please start your work !

Asteamhead