steam turbine and generator

[Paul HorthParticipant @paulhorth66944]

James,

 

Thanks for the photo. Your model certainly shows that it’s not necessary to use blades with difficult shapes to get a working result. If your turbine produced several watts then that is an impressive performance.

Could you tell us please how the steam enters and leaves your rotor? I can’t tell from the photo.

And, could you please give some details on the motor? The power of 36 Watt would seem to imply quite a large motor.

 

Thank you

Paul

[Keith Wardill 1Participant @keithwardill1]

Hi, Paul,

 

I can scan the Chaddock Turbine articles in the next few days – the easiest way would be to e-mail them to you as PDF files – I am not sure if I can add them as attachments via the ‘Message Member’ facility of this thread – if not, you could send me an e-mail address via the MM facility, and I can reply privately.

 

Keith

[William RobertsParticipant @williamroberts98085]

Hi Paul,

             We have a member known as Windy ,aka Paul who was making a turbine last year to drive a model speed boat , the last pictures I saw were the test nozzels he had made .I think he could help you .  I cannot see why you need anything running at 90,000 rpm ? if you need more power increase the number of stages , I take it you know about the higher the pressure the greater the temperature = more work. I will drop Windy a line and see if he will help you im sure he will.

         Regards Bill.

[Werner JeggliParticipant @wernerjeggli14222]

Paul,
somehow the forum mail does not seem to work wit me! So I try
a direct mail:

I'm the Swiss gentlemen who wrote the ME articles. This is the first
time I participate in this forum. I thought to have sent of a reply to your
problem about half an hour ago – but it does not show on the forum. So I try again.

My
turbines are the size you are looking for. They are described in ME 4281,
September 2006 (Tesla, mechanical) and ME 4318 and 4320, February 2008
Laval,turbine-electric). Try to get hold of these issues. For any futher questions please contact me directly.

A further contibution about my latest locomotive with turbine.electric
drive lies with ME since last June. They have not gotten around to publish it
yet.

Key to success is to keep electrical and mechanical losses of the
TG-unit as low as possible!

Werner
Jeggli/Switzerland
 

Edited By Katy Purvis on 01/06/2015 11:25:39

[Paul HorthParticipant @paulhorth66944]

Werner,

 

Thank you for your message. I have the magazines somewhere in the spare room, I will retrieve them and read about your turbine once again. I hope that your amazing train is running well, I consider this to be a heroic achievement of true model engineering. You have designed and built several complicated interacting systems and made everything work. I know how difficult that can be.

I would be interested in the details of the Swiss motor that you used as a generator, I expect that you have described that in the magazine.

Best regards

Paul

[Stephen RowleyParticipant @stephenrowley13300]

Hi Paul

Sorry I forgot about the in and out.

 The steam or in this case the compress air enters by a 1/8 hole at the top left hand side and out at the bottom right.

There were two more units one with 6 blades and the last with
4 and they were all on the one shaft. The air (steam) would enter the
first then into the second and the n the last.

 

The motor is just a standard motor that is for R/C cars so has a lot of out put for it’s size.

As you an see from the photograph the winding are quit large for the size of the motor.

 

James.

 

[Paul HorthParticipant @paulhorth66944]

James,

 

Thanks. I have looked up this motor and found this data, and a lower price!:

 

Mtroniks Vision 500 Marine >>

Mtroniks Vision 500 is a 540 size Johnson motor
This 540 sized Johnson high speed motor is ideal for marine use. Unit comes complete with motor suppresion capacitors.

Dimensions :
L57.0mm
D36.0mm
Shaft diameter 3.0mm
Voltage, 12V
Off load current, 1.18A
Max current, 54A
RPM, 16500RPM
Part No: V500M

Price: £4.99 (Including VAT at 20%)

This could be what I am looking for. From the data above I can calculate the performance as a generator and see if it could match the turbine. The speed is one of the highest I have found. I would then have to design a robust coupling and frame to hold the turbine and motor together.
Thanks for the help

Paul

[Ian S CParticipant @iansc]

Last week I did an experiment with a hot air engine I am developing, it sits on a stove, and has a fan in place of a flywheel.  I attached three magnets to the hub of the fan and placed two coilseithe side of the motor , and as close to the magnets as I could, this rough set up generated enough power to light up two LEDs, one red and one green, but not quite the current to run a 3V radio.  The motor was running at about 400rpm.  This would indicate that the suggestion of embedding magnets in the turbine wheel with a coil near by should work.  Ian S C

[Paul HorthParticipant @paulhorth66944]

Better late  than never?

 I have now re-read some of the turbine articles discussed above. The year 2008 Model Engineer had no fewer than three articles on miiniature steam turbines. Plenty for me to digest.

In several model turbine designs that I have seen, the blade or impeller cavity is a semicircular cutout formed by an endmill in the periphery. This is relatively easy to form and gives a kind of impulse action but is nothing like the impulse blades on a full size turbine. I have called these impellers “Stumpf” but I am not sure if this is the correct name. For these wheels, the steam jet is tangential. In some designs the steam jet is on the wheel cente line, so that the steam impulse is directed straight at the cavity, and the steam dissipates in all directions after hitting the wheel.This is not very efficient.  In others, the jet is offset to one side so that the steam flows around the semicircle and is reversed. This is a better way to capture the steam energy.

For a more efficient impulse blade, the steam is fed in from the side of the wheel, flows through the blade and out the other side, reversing its direction but keeping a high velocity. It is more difficult to cut blades suitable for this action.

 

I will briefly summarise the turbines in the 2008 articles, as they represent these different types.

 

(1) Raymond McMahon, No. 4332 and 4334 15-8-08 and 12-9-08.

This turbine has the semicircular cutouts with the jet on the centre line. Diameter is 1.5 inch, 31 mm. It drives a dynamo from a rechargeable torch. The power and rpm are not stated, but probably in the tens of milliwatts, to light some LEDs. The housing has been made to look very realistic.

(2) Malcolm Stride, No. 4328, 20-6-08

These are for driving a boat not a generator. Two wheels are described.

Wheel 1: Blade shape is hard to see in the photo. Dia 50 mm.Speed 105000 rpm, down to 30000 rpm on load. Performance – drives a 3.5 foot boat.

Wheel 2: Blade shape semicircular cutout, with jett offset to the side. Dia 40 mm. Speed 90000 rpm to 40000 rpm on load. Performance – drives a 4.5 ft boat.

This indicates to me that the blade shape of the second wheel gave an improved performance. Note the high speeds though.

(3) Werner Jeggli, no.4318 and 4320.

Herr Jeggli’s wheel is closer to a true impulse wheel, with side inlet and outlet and narrow curved passages in the periphery. Diameter 30 mm.Speed 53800 rpm no load, 34000 rpm at load. Power 4.4 watts. Smaller than the other wheels but I suspect more powerful because of the blade design.

 

When or if I make an attempt, I would aspire to make this kind of wheel, though i agree that the othr wheel do work and are thus good enough. It will also depend on what kind of motor I can use as a generator.

 

Paul

 

[VersabossParticipant @versaboss]

Hi Paul,

if you need a motor which will not disintegrate at turbine speeds, look at the so-called inrunners as used by the aeromodellers.

See e.g. this site:

http://www.jethobby.com.sg/cgi-bin/ezsite/index.cgi

select ‘brushless motor’,  then ‘GS inrunner’

The first I see, B-12-30 (12 mm dia, 30 mm length will turn over 45000 rpm on 12 v, and pulls 3 amps.

And there are others, even faster.

Even if it possibly is somewhat less as generator…impressive.

I admit that I have absolutely no experience with these or wit any similar motors. But that’s what I would look for.

Greetings, Hansrudolf

Edited By Versaboss on 16/01/2011 23:23:50

[DMBParticipant @dmb]

I seem to recall a steam gen. described in ME possibly back in 1970`s and the name of now late(?) Basil Palmer, South Africa.

John.

[Paul HorthParticipant @paulhorth66944]

Hansrudolf,

 

Thank you. That certainly is a fast speed. Do you know if this type of motor can be run as a generator?

This site seems to be in the USA, but I will look around for a UK supplier.

 

Paul

[VersabossParticipant @versaboss]

Paul, no they are in Singapore, and the prices are Singapore dollars  (100 SGD = 49 GBP according to my converter). But it seems they don’t have an online shop; I was a bit mislead here myself.

Edit: or maybe they have? I see now a ‘add to cart’ on some items!

Surely you can find a shop catering for aeromodellers, or try Ebay.

As I said I have no experience with these motors, but as they are principally ordinary DC motors (but with the windings outside and a magnet rotor in the case of an inrunner) I see no reason why they would not work as generators.

Edit 2: maybe the 3 leads would need to be connected to the usual 2 (+ / -) with diode bridges, if my theory of their working is correct.

I remember that quite a time back someone wrote an article in MEW about building an outrunner (where the windings are inside and the case with the magnets turn) for driving a milling spindle. These are not so fast, but have more torque.

I’m sure someone will bring forth the number of that issue.

Greetings, Hansrudolf

Edited By Versaboss on 17/01/2011 23:49:44

Edited By Versaboss on 17/01/2011 23:58:52

[AESParticipant @aes]

For Paul Horth,

 

If you’re looking for UK suppliers of aeromodeller’s electric motors (of all types) then do no more than visit WH Smith (or similar) and buy the latest copy of magazines like “RCM&E – Radio Control Models & Electronics”; or “AVI – Aviation Modeller International”. In both you will see pages and pages of ads for suppliers for such, ranging from big swish model shops to small 1 man band cottage industry-type outlets. 

 

Motors for all types of aero models (and cars too I think) have come on in leaps and bounds in recent years, and the power outputs, ampere ratings, sizes, and types (brushed, brushless, outrider, inrider, etc) are many and various.

 

I’m sure you can find something suitable for your needs – and if faced with the confusion of too many choices, both of the above mags have regular columnists who specialise in electrics who could no doubt answer queries.

 

Good luck.

 

Krgds

AES 

[Ian S CParticipant @iansc]

The model aircraft suppliers have alternaters for engine driven power supplies.

The generator I’m using on one of my newer engines is the motor out of a Braun stick blender, this is a bit the opposite of what you want, at around 1000rpm i’m getting 18V, if the generator is run up to full speed it would produce 220V, it’s a 500W motor about 60mm long X 30mm dia.  Ian S C

[Les Jones 1Participant @lesjones1]

Seeing Ian’s suggestion of using a motor from a blender made me remember some information I had seen on one of the Dyson battery vacuum cleaners.

The DC31 is claimed to use the fastest motor in the world which runs at 104000 RPM.

As this motor will have a rotor on the end of it it is almost a ready made turbine generator.

I imagine it uses the same basic design as model aircraft motors so it would need the inverter electronics removing and being replaced with a three phase rectifier.

Here is a link to a web page with a little information about it.

Dyson DC31 motor info.

Les.

[Anonymous]

Les,

Is it me, or is your link self-referencing? That could lead to infinite recursion.

Regards,

Andrew

[Les Jones 1Participant @lesjones1]

Hi Andrew,

No it’s not you it’s me. I must have copied the link from the wrong tab before pasting it into the URL box. Hopefully this attempt will be correct.

Dyson DC31 motor info

Sorry for the error (And for not checking that the link worked.)

Les.

[Paul HorthParticipant @paulhorth66944]

Gents,

Thank you all very much – i now have several references for high speed electric motors which I need to look into, to be driven by a turbine,

It will be no surprise to anyone that I do not plan to start making a turbine tomorrow! I will need to think a bit more about the design (thinking is cheap) then decide if I am ready to commit time and effort to actually cutting metal. If and when I do, I will be sure to report back to this forum. I have had a lot of help from here, just in a short time.

Les – I think that Dyson motor would have too much power for me. The impeller in Sir James’s right hand looks to be the wrong shape for a steam turbine but I guess it coul be changed. One for bigger bys than me I think.

Paul

[PekkaNFParticipant @pekkanf]

OT:

I found a picture of the motor here:

http://0.tqn.com/d/dogs/1/0/O/0/0/-/dyson-motor.jpg

It’s middle of this page:

http://dogs.about.com/od/productreviews/fr/dysondc13animal.htm

I would love to know details of the motor and the bearings, but it looks (completely off hand) to me a bit strange that the simple armature winding on the picture would be any good of frequency of the SR motor of quoted speed.

EOT****

I found some comparison of different generator types used on (a LOT bigger) Microtrbines:

http://www.electrodynamics.net/documents/electrodynamics_power_gen2002.pdf

Casual look shows that layman is confronted with excitation problems and desingn complexities. This might make SR design less appealing.

Is there any other alternative to produce a lttle electricity on turbine lookking structure? Turbines don’t scale well. Anything in the domain of rotary piston or air vane motor?

I have tought of cannibalizing a chep pencil grinder or a small die grinder.

Or it really HAS to be TURBINE? Oh. dear!

PekkaNF

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

The older type air driven dentists drill has a very effective turbine system in a tiny space and they output several watts shaft power .

[Ian S CParticipant @iansc]

I’v just been thinking, with a bit of work ,you could make an axial piston motor with a swash plate drive, it would outwardly look similar to a turbine, and be economical on steam, and have more power and lower revs., just taking PekkaNF’s last statement,Or it really HAS to be TURBINE? Oh, dear! Ian S C

[Brian Baker 2Participant @brianbaker2]

I have read this topic contributions with interest, and hope that contributors will be interested in a photo of the turbo generator that has been fitted to my 7 1/4 gauge tank loco for some 20 years.

It uses a turbine cut into an 1 1/8 in diameter p/bronze disc, using an endmill to produce half moon shaped recesses. The jet of steam enters the turbine wheel on one side, and exits via the long slot on the top. Steam consumption is unnoticed, and appears minimal.

I used an expensive second hand swiss DC motor, having tried various cheaper ones, whose commutators gave up. I tried making the wound coil alternator type, but found it very critical with the gap between the rotating magnet, and the stator coil. running at high speed, I found the ball races moving in the aluminium casing, and after a few runs, it started to jam, doubtless due to my poor buliding technics.

The current set up runs at about 5 to 10000 r/min, and generates enough power to light 3 X 3 volt filament lamps, well enough to light the cab, the pressure gauge, and the water gauge.

Brian

Edited By Brian Baker 1 on 20/01/2011 13:26:40

Edited By Katy Purvis on 01/06/2015 11:32:45

[Brian Baker 2Participant @brianbaker2]

Here is the photo

[Paul HorthParticipant @paulhorth66944]

Ian,

What attracts me about a turbine is the inherent simplicity, i.e. one moving part. The idea of making an axial piston swashplate engine, with three cylinders, valves, funny crank joints etc etc is rather more complex with umpteen smallmoving parts and does make me shiver. I can think of many problems with this, starting with the design.I don’t actually need to make the electricity, you see. The turbine would just be a neat gadget like the one that Brian has shown. I’d still like to try an impulse wheel with through-flow passages, though. It would be parasitical on the traction engine boiler and the engine-driven pump.

One major problem with a stand-alone steam turbinewould beproviding an effectivewater pump, which would have to be driven through a massively reducing gear train. Even Prof Chaddock had problems, having to cut his own gears for this. He was trying to pump into a flash steam boiler at 500 psi though which is pretty damn ambitious.

Paul

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