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Tiny Steam Turbine
By WXYZCIENCE, Section Steam Posted on Sun Jan 13th, 2008 at 09:43:27 PM MST
One Hundred Thousand rpm Class

I haven't posted for a while but I have been watching the board. This project has got me real excited and has real potential. I have been working on Steam Turbines for about five years and have started on my first one hundred thousand rpm unit. The first picture is of the turbine blade, a modified compressor wheel from an old auto turbocharger.

Sand had got into the turbocharger and destroyed the outer edges of the wheel. I machined the damaged part off and then balanced the wheel again. The first tests at speeds of one hundred thousand rpm, kept me thinking about my dentist.

The Turbine Housing is made of brass and consists of two halves, it is then sealed by a copper gasket. Eight stainless steal machine screws hold the housing together.

The clearance is just two thousands of an inch.
The last picture is the assembled turbine unit.

I am now working on the Teflon Seal and bearing mounting assemblies which will be posted this week.
Joseph.

Tiny Steam Turbine | 15 comments (15 topical, 0 editorial)

Re: Tiny Steam Turbine (3.00 / 0) (#1)
by 2dumb2kwit on Sun Jan 13th, 2008 at 03:45:46 PM MST
(User Info)

Dentist?.......The first test at 100,000rpm would've had me thinking that a proctologist could lose a finger!!!

Great work, please keep us up to date.

Re: Tiny Steam Turbine (3.00 / 0) (#2)
by SparWeb (sparweb at ANTISPAM_hotmail_com) on Sun Jan 13th, 2008 at 06:55:52 PM MST
(User Info)

100,000 RPM?!!
Yup, I'm very eager to see what bearings you use!
Every inch-pound of friction will release 1200 watts of heat at that speed.
Considering all the clever stuff you've come up with before, I bet you can overcome that, too.
Steven Fahey

Re: Tiny Steam Turbine (3.00 / 0) (#3)
by mikeyny on Mon Jan 14th, 2008 at 06:31:19 AM MST
(User Info)

Most if not all turbo chargers have an oil injection system that runs off the crankcase oil. They fail when the oil fails to flow to them. Will you have an oiler of some sort to help keep it cool.
Mike
"I thought I made a mistake but I was wrong"
[ Parent ]

Re: Tiny Steam Turbine (3.00 / 0) (#4)
by WXYZCIENCE on Mon Jan 14th, 2008 at 09:31:12 AM MST
(User Info)

Steven, I have done some research into oilers for miniature bearings. In combination with a floating high temperature teflon seals they work well into the 200,000 sm range. I find more problems in the weight of my oil. I need a turbine oil. I have also looked into carbon graphite, they can take the heat but the shaft has to be very hard around 400 for long life. I can't work without precision grinders. Thanks for the input.
Joseph.

[ Parent ]

Re: Tiny Steam Turbine (3.00 / 0) (#5)
by Janne on Mon Jan 14th, 2008 at 10:39:31 AM MST
(User Info) http://www.anotherpower.com/gallery/janne

It's propably guite obvious, but i can't seem to figure out where the steam comes in and exits?

Janne
contact: #tuulivoima @ircnet or #otherpower @irc.otherpower.com

Re: Tiny Steam Turbine (3.00 / 0) (#6)
by ruddycrazy on Tue Jan 15th, 2008 at 12:06:05 AM MST
(User Info)

Hiya Joesph,
Eh mate the bearings that you intend to use could you post the part numbers for them and I can check them out in my bearing books. Also provide the inside,outside and thickness dimensions and i reckon I can find the best suitable bearing as i'll ask a Timken engineer which I have at my disposal for any bearing Q's

Cheers Bryan :)

Re: Tiny Steam Turbine (3.00 / 0) (#7)
by JW on Tue Jan 15th, 2008 at 06:19:48 PM MST
(User Info)

Joseph,

Do you realize that you are working with the impeller section of the turbo assy?

Most of these units are designed to go no faster than 80,000 rpm(80k).

"The first picture is of the turbine blade, a modified compressor wheel from an old auto turbocharger.
"

That is essentally correct, but why, are you trying to drive a compressor blading assy, with steam?

If I were you, I would abandon this section of the turbo, and install- 4 1/2inch nozzels, tangentally at 90* to 180* vertical of the actual turbine half(exhaust housing) of the turbo. Although this does not account for the compress-ability of air, I feel you could do quite well with such an arrangement, using High flow volume rates of steam. Also you must get the oil-bearing up and running with some sort of oil-pump to the centre bearing. Its probably best to sparge the original air(combustion product gass inlet) with the output from the impeller section. In this way you could sparge aire into the cast-iron housing (stainless steel) with each of the 4 1/2in steam inlet nozzels. Have you noticed the vaning of the exhaust turbine?

You could safely gear down the shaft(@80k) to a system of high-speed belts to drive an alternator at 3000rpm. But balence issues would surly arise, on your pto-shaft. Unless your planing to use volume flow to drive another 'reaction' turbine set, which I feel is not the case based on your comments. By the way which element of the turbine shaft are you going to convert to the pto? be vary carefull when contemplating the 'open' end of the shaft. (pto, power take off)

Re: Tiny Steam Turbine (3.00 / 0) (#8)
by WXYZCIENCE on Wed Jan 16th, 2008 at 12:45:00 AM MST
(User Info)

JW, the compressor section of the turbocharger was chosen for it's weight better the lack of it. What I am up to is building a reaction stage turbine. The impulse type make to much noise. Removing the lower part of the blades, this have allowed me to use very small nozzles and achieve the expansion through the wheel that I was looking for. The alternator is directly coupled to the output shaft. It also supports the pto end. The first test with the alternator have allowed me to take the power off at these very high speeds. I suspect that the full output range will be a little lower that the max. speed of the turbine. Around 70K. If all goes according to the plan the entire unit and flash boiler will weight under ten pounds. I expect no more that marginal power output, 20 watts. Joseph.

[ Parent ]

Re: Tiny Steam Turbine (3.00 / 0) (#9)
by JW on Wed Jan 16th, 2008 at 05:16:20 PM MST
(User Info)

Interesting,

So you are going to run it backwards with nozzle's. Basically you can use whatever housing you wish in that case. That would nullify the cyntrifugal aspect of the compressor/impeller your using. I cant wait to see an update, that is a cool project.

I was thinking using a roots type blower would be more simple, for a steam type of application( the expander),but I like your idea.

JW

[ Parent ]

Re: Tiny Steam Turbine (3.00 / 0) (#10)
by spinningmagnets (velmis1450bc(at)aol(dot)com) on Wed Jan 16th, 2008 at 05:36:40 PM MST
(User Info)

I'm always interested in the projects you post! Can you drop a hint about the configuration and rough specs on the PMA you plan on using?

I recall a company called Capstone using a gas turbine (jet) made from turbocharger parts to spin a generator. Their biggest customers were off-shore methane drilling rigs that had used diesel gens for power. The gas turbine could burn fairly "wet" methane with minimal filtering. I was curious what a small ultra-high-RPM PMA would look like.

Re: Tiny Steam Turbine (3.00 / 0) (#11)
by WXYZCIENCE on Wed Jan 16th, 2008 at 06:11:33 PM MST
(User Info)

Spin..., the major problem I have found about high speed PMA's is the heat built up in the coils. My tests with different coils showed that I could remove all of the heat by the use of litz ( multiple strands) wire, this coil is one that is used in my 12000 rpm unit.

The one's that I will be using in the 100k will probably have 10 strands of 40 guage and very few windings. I worked today on the mounts that will hold the turbine and alternator square to each other. I hope to post some more pictures this weekend. Joseph

[ Parent ]

Re: Tiny Steam Turbine (3.00 / 0) (#12)
by Nothing40 (phattymo (at) gmail (dot) com) on Sat Feb 16th, 2008 at 08:07:07 AM MST
(User Info) http://www.users.qwest.net/~ptaylor/

Hmm,Maybe "skin effect" has something to do with the wire heating up?

http://en.wikipedia.org/wiki/Skin_effect

[ Parent ]

Re: Tiny Steam Turbine (3.00 / 0) (#13)
by joestue on Sat Feb 16th, 2008 at 08:46:32 AM MST
(User Info)

Nope, at 12000 rpm and say 4-6 poles the frequency is 800 to 1200 hz.
A 5.8 mm diameter wire would have its resistance increased by 10% at 1200hz.

EDDY CURRENT is the problem.
We ignore it at 300 rpm because it scales with the square of the frequency.
WXYZCIENCE is dealing with 400 to 900 times the effect at 300 rpm.
those numbers may be off by a factor of 2, but you get the idea.

[ Parent ]

Re: Tiny Steam Turbine (3.00 / 0) (#14)
by WXYZCIENCE on Sat Feb 16th, 2008 at 09:45:21 PM MST
(User Info)

joestue, Yep I also agree with your logic. By using several strands I can reduce the eddy current considerably.
Joseph.

[ Parent ]

Re: Tiny Steam Turbine (3.00 / 0) (#15)
by ghurd on Sat Feb 16th, 2008 at 10:39:55 PM MST
(User Info)

Wow! I should have said that before.

Any idea how it would work with water/hydro?
As in a more, let us say, 'not modified' or just like GM made it kind of turbine.
I don't know if the expansion you modified it for would pertain to water.

I have no idea what it looks like before you started.
I have no idea about the bearing issues with water.
I am 100% positive I can't do what you did.

G-

Tiny Steam Turbine | 15 comments (15 topical, 0 editorial)

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