Are dynamos too noisy?

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RET
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Location: Toronto, Canada

Re: Are dynamos too noisy?

Post by RET » Wed Apr 24, 2019 8:28 pm

Hi,

Reading this over, I apologize for the way it sounds, but what I say there is still true.

When you come right down to it, whether you put one of these on your locomotive is purely a personal decision, but I kind of like the idea of being able to turn a valve in the cab and have the headlight come on; but then that's just the way I feel.

If I'm going to build something, I would like to have it work the way it is supposed to, but then that again is just the way I see things.

Sorry if I may have ruffled anyone's feathers.

Richard Trounce.

RET
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Re: Are dynamos too noisy?

Post by RET » Wed Apr 24, 2019 9:06 pm

Hi Greg,

Actually, making the turbine is one of the easier parts. All you need is a blank wheel of the proper size and shape, a simple "G" code program in a Sherline CNC mill (or the heavier machine that I finally made for myself), a proper cutter to cut the individual buckets and then just sit back and watch the machine work.

Alternately, you can use a conventional mill with a rotary table turned on its edge and then do manually what the "G" code program does as follows.

Go in, cut the left bucket first and retract the cutter, next move to the right and cut the right bucket (this removes the burr that was generated when you cut the left bucket). Retract the cutter and move back to the first position. Now, index the table the proper number of degrees to cut the next pair. Repeat until you have gone all the way around. There should be about 30 buckets, give or take a few on the finished wheel.

Using CNC is better since it doesn't get tired and doesn't do "oopsies."

Probably the most difficult part is making all the housings so they look right and are done to the necessary accuracy, but the critical part is to make the rotor so it can handle 40,000 rpm. and still stay in one piece.

Another important part is making the nozzle, because that affects the turbine efficiency a lot. The inlet cone needs to have the same shape as the inlet cone on an injector while the outlet cone needs the same shape as the recovery cone in an injector (the combining cone is missing). Where they meet, the bores have to match in diameter, but there needs to be a relatively abrupt change in the wall shape between the two. This "bend" in the wall if done right will cause the flow of the jet to become supersonic thus increasing the efficiency even more.

There's more, but this is a lot of it.

Richard Trounce.

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Greg_Lewis
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Location: Fresno, CA

Re: Are dynamos too noisy?

Post by Greg_Lewis » Wed Apr 24, 2019 9:14 pm

RET wrote:
Wed Apr 24, 2019 8:28 pm
Hi,

Reading this over, I apologize for the way it sounds, but what I say there is still true.

When you come right down to it, whether you put one of these on your locomotive is purely a personal decision, but I kind of like the idea of being able to turn a valve in the cab and have the headlight come on; but then that's just the way I feel.

If I'm going to build something, I would like to have it work the way it is supposed to, but then that again is just the way I see things.

Sorry if I may have ruffled anyone's feathers.

Richard Trounce.
Not at all, Richard. I am interested in all points of view. My emotional self wants a working one just because. My rational self says I've got enough projects on the do-list already and these castings have been sitting for perhaps 15 or 20 years, and my heirs will just throw them away if I don't make something out of them.
Greg Lewis, Prop.
Eyeball Engineering — Home of non-interchangeable parts.
Our motto: "That looks about right."
Celebrating 30 years of turning perfectly good metal into bits of useless scrap.

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NP317
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Location: Northern Oregon

Re: Are dynamos too noisy?

Post by NP317 » Wed Apr 24, 2019 10:45 pm

Marty_Knox wrote:
Wed Apr 24, 2019 2:16 pm
There are firemen on full-size locomotives who complain about noisy turbos. In fact, I believe Pyle-National sold mufflers for the exhaust.
I concur, from personal experience.
~RN

rkcarguy
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Re: Are dynamos too noisy?

Post by rkcarguy » Wed Apr 24, 2019 11:51 pm

Steam (and moisture), bearings, heat, lots of RPM, and metal....what can go wrong lol:)

Asteamhead
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Re: Are dynamos too noisy?

Post by Asteamhead » Thu Apr 25, 2019 10:39 am

Hello Greg_Lewis,
Is this you want to hear?
Working brushless turbo generator, scale 1 in 10 (about of 1 " diameter). About 5 to 10 W output with just a teeth wheel as turbine.
https://www.youtube.com/watch?v=1wf-jVKJ9Xw
Good luck!
Asteamhead
Attachments
TG  04 red.jpg
Working turbo generator scale 1 in 10

Wolfgang
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Re: Are dynamos too noisy?

Post by Wolfgang » Thu Apr 25, 2019 8:31 pm

Hi Richard T. Yes indeed I am a retired Professional Engineer but, like you, in the mechanical engineering discipline.:-)). Mind you, I have done quite a bit of structural work for industrial applications, including large machining fixtures and lift beams... And yes I studied several courses in turbo-machinery, a long time ago. But it is like swimming or sex; once you know how...

I have built a 3/4" to the foot scale Canadian Pacific Hudson, ol' 2888, complete with functioning duplex boiler feed pump and fully functioning scale-sized turbo-generator. As Richard stated he/I like the idea of cracking the steam valve and voila, instant head and cab lights. (T/G with pics is described elsewhere in this blog, also the duplex pump).

Mine has a 5/8" dia. rotor (turbine runner) with 12 buckets in the 1/2 half Pelton bucket wheel arrangement; this arrangement puts a very light end load on one bearing but is more efficient than a full Pelton bucket because of the reduced surface friction. The nozzle has a 1/32" dia throat with a short 30 deg. included expansion cone. The rationale for this short expansion section is that surface friction in these tiny flow passages is a large portion of the overall friction, and it is best to minimize this.

With a coal fire and running around the track the steam consumption of the T/G is not noticeable and yet, when I run the loco on the roller track at home the full output of a 1" dia. propane torch in the firebox is required to keep up the steam pressure when running the T/G.

Running on air in the workshop the thing is noisy, quite objectionably so. But running outside, especially in open spaces, the whine is barely noticeable.

With a modicum of pre-production planning (one of my specialties) the building of a functioning T/G is not that difficult unless you want a model that looks exactly like the full sized one. I am certainly not one of those masochists and am happy with capturing the essence of the full size machinery.

Heck, anyone who can build a duplex pump, such as mine, or Dan's cross compound air compressor (what a tour de force!) can build a functioning T/G, just like on the big 'uns. Give it a go and to heck with fakery!!! Wolfgang

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Greg_Lewis
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Re: Are dynamos too noisy?

Post by Greg_Lewis » Thu Apr 25, 2019 9:30 pm

Asteamhead:

Thanks for the demonstration. Your work is at the top of the list in quality and aesthetics. It makes me want to toss all my junk into the dumpster and take up stamp collecting. (Take note of the last line of my sig....)

Wolfgang:
You write: "the building of a functioning T/G is not that difficult unless you want a model that looks exactly like the full sized one. I am certainly not one of those masochists..."

I am one of those. They tried medication but it didn't work. :wink:
Greg Lewis, Prop.
Eyeball Engineering — Home of non-interchangeable parts.
Our motto: "That looks about right."
Celebrating 30 years of turning perfectly good metal into bits of useless scrap.

Wolfgang
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Re: Are dynamos too noisy?

Post by Wolfgang » Fri Apr 26, 2019 10:02 am

rkcarguy wrote:
Wed Apr 24, 2019 11:51 pm
Steam (and moisture), bearings, heat, lots of RPM, and metal....what can go wrong lol:)
You probably don't realize this but you have nailed THE major problem I encountered: Moisture. Even with a clear space between the turbine section, with flinger, and the bearings and alternator, rust within the alternator was a problem.

The bearings I purchased from a manufacturer in California who lubricated them with a very light high temperature grease when I explained the usage to them. They also estimated the life expectancy to be about 100 operating hours in that application.

But, the inside of the alternator would rust, and that rust got into the bearings which were shielded but not sealed, playing havoc here and shortening the life to a few running hours.

My son cleaned the insides of the alternator and coated everything corrodable with a very thin layer of epoxy. This cured that difficulty and we have not experienced any more problems.

Mind you, the dynamic balancing could stand improvement and I welcome any suggestions and ideas to that end.

The T/G runs at about 60,000 rpm illuminating the 3 Watt LED headlight to blinding brightness. With people around we turn down the speed so as not to cause discomfort. Wolfgang

rkcarguy
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Re: Are dynamos too noisy?

Post by rkcarguy » Fri Apr 26, 2019 10:32 am

Wolfgang wrote:
Fri Apr 26, 2019 10:02 am
rkcarguy wrote:
Wed Apr 24, 2019 11:51 pm
Steam (and moisture), bearings, heat, lots of RPM, and metal....what can go wrong lol:)
You probably don't realize this but you have nailed THE major problem I encountered: Moisture. Even with a clear space between the turbine section, with flinger, and the bearings and alternator, rust within the alternator was a problem.

The bearings I purchased from a manufacturer in California who lubricated them with a very light high temperature grease when I explained the usage to them. They also estimated the life expectancy to be about 100 operating hours in that application.

But, the inside of the alternator would rust, and that rust got into the bearings which were shielded but not sealed, playing havoc here and shortening the life to a few running hours.

My son cleaned the insides of the alternator and coated everything corrodable with a very thin layer of epoxy. This cured that difficulty and we have not experienced any more problems.

Mind you, the dynamic balancing could stand improvement and I welcome any suggestions and ideas to that end.

The T/G runs at about 60,000 rpm illuminating the 3 Watt LED headlight to blinding brightness. With people around we turn down the speed so as not to cause discomfort. Wolfgang
Thats the major issue, one can make the "turbo" with brass or stainless steel so it doesn't rust, but the bearings still need to be ball bearings due to the tiny size as I'd imagine bushings would not spin free enough. Seals would likely not take the heat, so shields have to be used so that means moisture can get in. My experience lies in full size turbo's on marine engines....salt water a.k.a. "the acid" ruins everything.

Regarding balancing, back in my RC car days I had this little stand with bearings on it that I could put my motor armatures on and balance them. In these days, hand-winding the armature with care resulted in alot more giddy up and better battery life.

Wolfgang
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Re: Are dynamos too noisy?

Post by Wolfgang » Sat Apr 27, 2019 11:44 am

Alternators/generators of necessity have soft steel and laminations in order to provide a suitable magnetic circuit. And these will rust very easily. Nickel plating would probably work but we used epoxy coating which provided very good corrosion protection in the alternator section.

Everything else was made from brass or bronze.

Seals cannot be used in these "fly power" applications because the starting torque is too low to overcome the static friction. The ball bearings themselves are stainless steel. Plain bearings have too high friction factor too. Wolfgang

Asteamhead
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Re: Are dynamos too noisy?

Post by Asteamhead » Sat Apr 27, 2019 6:51 pm

Wolfgang,
Look, here is the solution - done:
(Took me some time to gather and adept the old fotos and drawings).
The prototype has an extension combined with the wheel which holds two piston rings. These slip into the bore of the housing and will
move slightly until they aren't in touch with the hub (piston) any more. Problem solved :!: This works within the model, too! A separate space with a centrifugal disc on the shaft will throw out moisture. Worked 500 h by saturated steam before the stainless ball bearings got defective :D .
To reduce problems due to balancing, the wheel made of aluminium is pressed onto a precise hub wich acts as piston, too. This combination is pressed slightly on the precise shaft of the brushless servo motor used as generator. It may be removed by means of an inside thread and srew to avoid any axial stress to the bearings :idea:
And now sit down please and don't heasitate building a turbo generator of your own :wink: . Perhaps you could improve this construction :idea:
Asteamhead
Attachments
TG AEG drawing, red.jpg
AEG Prototype. Shows sealing by means of piston rings
TG AEG , sealing by means of 2 piston rings,red.jpg
Cross section, piston rings and centrfugal disc are to be seen!
TG solution for shaft sealing without friction, red.jpg
Principal scetch of the sealing. Centrifugal disc not shown yet
TG 1 in 10 scale, sealing without friction, red.jpg
Old drawing of a scale 1 in 10 TG

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