High frequency combustor for micro turbines

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Viv
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High frequency combustor for micro turbines

Post by Viv » Sat May 17, 2008 7:47 pm

Hi Guys more on this topic later I was just testing out the new forum for Mike.

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Re: High frequency combustor for micro turbines

Post by Mike Everman » Sun May 18, 2008 3:21 am

Thanks, Viv! Looks OK so far...
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Re: High frequency combustor for micro turbines

Post by Bruno Ogorelec » Sun May 18, 2008 9:48 am

Damn you, Viv, don't just whet my appetite and then leave me hungry!

And yes, happy birthday!

You're getting older by the day. At this rate, you'll catch up with me soon.

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Re: High frequency combustor for micro turbines

Post by Viv » Sun May 18, 2008 4:33 pm

Hi Bruno

Thanks for remembering my birthday ;-) I am moving gracefully towards being an old git too ;-)

I thought that high frequency burner cans would snag your interest, its some thing thats been knocking around in my mind for a long time now as these small turbines have such a short overall gas transit time to complete their combustion and generate maximum heat, some thing like that old SNECMA drawing but brought up to date with the micro valveless designs that were shown on the forum a while back.

Its not all of it you understand but the rest I will add as I get time, its pretty busy for me at the moment with my other projects, this one would be just for fun and out in the public domain.

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Re: High frequency combustor for micro turbines

Post by Bruno Ogorelec » Sun May 18, 2008 5:53 pm

That brick thing... I've been thinking about the nature of art, the position of artist etc. for ages. Finally, I came to the conclusion that art is in the eye of the beholder. What does that mean? It means that the artist has more or less no say in this. His view is almost irrelevant. It is you and I and other peers who determine whether something is art or not. An artist can persuade us through the sheer force of his art, but it is not his to pronounce on it. It is ours.

An extension of this, which is not perhaps immediately obvious, is that art must be craft, first and foremost. A craft can be a profession. Art as profession is bullshit. A thoroughly misconceived semi-Socialist idea.

So, you have a craftsman who knows his job and produces things that are either useful or appeal to the senses or both. Sometimes, this appeal transcends craft and appeals to the senses so strongly that it inspires some kind of emotional epiphany, joy, pity terror etc. This is art. If the craftsman is able to do generate such emotional effects on a regular enough basis, we can call him an artist.

I do not care what form the art takes. A T57 Bugatti Stelvio is just as much art as the most recent whoppingly priced Lucien Freud nude, or a Tahiti scene by Gauguin. Or a Mozart suite. Or a nice poem.

I don't give a shit for art that is not craft. The craft need not be obvious, but the artist must have proven his craft. Take Picasso. I am able to enjoy even his outrageous deconstructions of the human figure and accept them as a kind of artistic research, as striking out in new and unexplored directions, but only because I have seen that he is not an impostor. Picasso paid his dues in the early carreer and showed his craft.

He has shown his ability to function within rules. (Not an easy thing.) Thereafter, I accept (and respect) his need not to be bound by those rules. He has won the right to demand an effort from me toi understand what he's trying to do. Some punk who can only stuff dead animals or crap on his canvas, but has never paid his craftsman's dues, does not have this respect. If I were a sheriff, I'd ask him to leave the town by next morning or else.

But then, I'm a reactionary fuddy-duddy.

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Re: High frequency combustor for micro turbines

Post by Viv » Mon May 19, 2008 2:06 pm

Bruno

A superb and reasoned repost, the Brick blog was a some thing that first came to mind while discussing Mark Rothko's peace Orange and Yellow with Nicole, an artist of some skill herself, needless to say I love it and she hates it, I fully agree with you that an artist must also be an accomplished craftsman not only of adequate skill but a superb level of skill, the act of creation must not be held back by a lack of skill in its realization, how else can the painters vision be translated to canvas if he cant paint.

The Bugatti is perfect for this discussion as it encompasses the creative art and the craftsman's skill in its application, the line between art and craft is blurred by the collective execution of the complete car.

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Re: High frequency combustor for micro turbines

Post by Viv » Mon May 19, 2008 5:27 pm

Here is a nice idea to reduce the high pressure fuel pump requirements for fuel atomization, this is some thing that could be added to small turbine design fairly easily but I have always wondered why it has not?

Here is a link if you want the original or to search for related patents

http://www.patentstorm.us/patents/006983606.pdf

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Re: High frequency combustor for micro turbines

Post by Bruno Ogorelec » Mon May 19, 2008 6:57 pm

Interesting. Looks simple enough. Should be tried, I guess.

One thing I have been thinking about is a rotating combustor. Wouldn't centrifugal force provide high pressure and thus higher compression than in a stationary combustor can? Feed the air from the compressor axially into a rotating combustor and have it compress further, radially, inside the can.

Most of the combustion would take part near the combustor wall, I guess, so it would be good to have it insulated, and it would have to be built to withstand extra pressure, but it doesn't look like an insoluble problem to me.

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Re: High frequency combustor for micro turbines

Post by Viv » Mon May 19, 2008 7:32 pm

Bruno

Probably you and I are not the only ones to have wondered about that one ;-) density effects are interesting in a rotating frame like this, there was a gas lens made using a heated tube spun up to high RPM, hot gas and cold gasses stratify, also a deicing system for Rolls Royce turbines to keep the spinner cone free of ice, they found that heated air naturally flowed up the hollow central shaft to the nose cone and cold air flowed back! denser air was spun to the outer edge while heated less dense air took up the inner area.

The mass of the cc spinning would pose a significant gyro moment I would assume too, along with the other engineering issues, my own thoughts are moving along the line of front mounting an undercut groove on the impeller vanes with spillways to accelerate and atomize the fuel, increasing path length mixing is my immediate goal as lean premixed charges tend to favor none steady combustion modes.

Coupled to this the latent heat of evaporation of the fuel and its direct effect on cooling the air charge and increasing the charge density to the cc..

There is plenty of stuff out there but not a lot seems to be ending up in the small hobby turbine field, that seems odd to me as saving the cost and complexity of a fuel pump for a simple modification to a compressor wheel seems worth while to me.

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Re: High frequency combustor for micro turbines

Post by Mike Everman » Tue May 20, 2008 4:02 am

Seems we've all got whirly-gigs on the brain. I made a spreadsheet for that centrifugal compression. Gotta find that. I remember being surprised at how little compression was realized. I thought it would be a lot more.
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Re: High frequency combustor for micro turbines

Post by Bruno Ogorelec » Tue May 20, 2008 5:18 am

Mike Everman wrote:Seems we've all got whirly-gigs on the brain. I made a spreadsheet for that centrifugal compression. Gotta find that. I remember being surprised at how little compression was realized. I thought it would be a lot more.
Remember this one?
Damn, Mike, why do you have to intrude with rude reality? It was such a beautiful idea.

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Re: High frequency combustor for micro turbines

Post by Mike Everman » Tue May 20, 2008 5:49 am

Ha ha, I'll go back to my cave now... ;-)
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Re: High frequency combustor for micro turbines

Post by Viv » Tue May 20, 2008 2:17 pm

And it was so pretty too ! who wants physics to intrude ;-)

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Re: High frequency combustor for micro turbines

Post by marksteamnz » Wed May 21, 2008 9:17 am

Hmm a pity it isn't feasible on a small scale. Somewhere in my disorganized list of bookmarks is a link to a proposal exploring a rotary rocket motor. The rotation of the motor provided suction, pressurization and mixing and feed and aerospike type chamber.
This link is a step along the way http://web.mit.edu/cats/www/resources/Carl_talk.pdf but is not the proposal I've seen as it was huge! (greater than 1m diameter?)
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Re: High frequency combustor for micro turbines

Post by Viv » Wed May 21, 2008 1:51 pm

Hi Mark

Was it called the ram-disc or something? maybe rocket-dyne? I recall the one your talking about and if I remember correctly it may even have been Bruno who originally posted it to the forum.

They all seemed to make a certain kind of sense but the devil was in the details as Mike pointed out and the lack of compression plus path length got them.

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