Hello
Has anyone tried to build a small steam turbine and extract shaft power out of it? Ive seen small experiments with tesla turbine like constructions, but nothing more complex or sophisticated.
I have been wondering that why anyone hasn't built any steam turbines for smaller scale applications. From what I've heard they only use steam turbines in powerplants. What makes gas turbines so much better for example in turboprop aircraft? Somehow I see great potential in steam turbines.
I think that the lag with the rpm wouldn't be a very big problem because the propeller angle of attack is variable. The largest issue I see at the moment would be the time it takes to get it running properly, but again all aircraft prechecks and engine warm ups take lots of time so I suppose it wouldn't be the biggest time waster.
Steam turbines
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racketmotorman
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Hi Maikkel
Steam turbines are heavy by nature, due to the steam generating equipment , not the turbine wheels .
There's also the matter of water to turn into steam , it also weighs a lot , and unless some sort of condenser is used to recover the "used" steam and turn it back into water that can be pumped back thru the steam generator , you'd need to supply an enormous weight of fresh water from somewhere .
There have been plenty of small steam turbines used for maritime electric power generation in the days of steam piston powered craft .
Gas turbines are used in aircraft because the air which the engine uses is all around the aircraft and doesn't need to be carried onboard , as would be the case with having to carry the water if steam turbines were used .
Cheers
John
Steam turbines are heavy by nature, due to the steam generating equipment , not the turbine wheels .
There's also the matter of water to turn into steam , it also weighs a lot , and unless some sort of condenser is used to recover the "used" steam and turn it back into water that can be pumped back thru the steam generator , you'd need to supply an enormous weight of fresh water from somewhere .
There have been plenty of small steam turbines used for maritime electric power generation in the days of steam piston powered craft .
Gas turbines are used in aircraft because the air which the engine uses is all around the aircraft and doesn't need to be carried onboard , as would be the case with having to carry the water if steam turbines were used .
Cheers
John
Hello.
Thanks for the reply. Obviously if such an engine would be adapted to aircraft use, it would have to be a closed loop system with only a small water amount on board. I strongly also belive that the boiler construction could be made reasonably light, so that the overall weight of the engine would not be more than for example a piston engine of similar power. Wouldnt the concept be worth a try?
Thanks for the reply. Obviously if such an engine would be adapted to aircraft use, it would have to be a closed loop system with only a small water amount on board. I strongly also belive that the boiler construction could be made reasonably light, so that the overall weight of the engine would not be more than for example a piston engine of similar power. Wouldnt the concept be worth a try?
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racketmotorman
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marksteamnz
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As John has said it's the bulk of the condensers and heat exchangers. In small sizes ie below 500hp it's VERY hard to get the total system efficiency up with out weight and bulk. Google Lear steam turbine and stuff should come up. By the way this also won't be a cheap project. You are building a complete power plant from scratch.
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Irvine.J
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I agree with the other two on this, absorbing the heat for extra power usually involves alot of copper or a water jacket which dont work particularly well as far as we've found. Thats not to say dont try, I always suggest following your heart.
But, if you made a little system that could provide electrical power (Through a very small altinator or similar,) I would be particularly interested. Something to keep my batteries charged even. That shouldn't be too heavy considering the high performance electric motors and gizmo's out there.
Its definitely a step in the right direction in terms of flight, electrical power provided by the engine would be a very big step forward, if made light enough.
But, if you made a little system that could provide electrical power (Through a very small altinator or similar,) I would be particularly interested. Something to keep my batteries charged even. That shouldn't be too heavy considering the high performance electric motors and gizmo's out there.
Its definitely a step in the right direction in terms of flight, electrical power provided by the engine would be a very big step forward, if made light enough.
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racketmotorman
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As far back as the beginning of the 20th century, engineers were trying to build a practical gas turbine because the steam apparatus was so bulky and heavy that it only really made sense in BIG applications.Maikkel wrote:Hello.
Thanks for the reply. Obviously if such an engine would be adapted to aircraft use, it would have to be a closed loop system with only a small water amount on board. I strongly also belive that the boiler construction could be made reasonably light, so that the overall weight of the engine would not be more than for example a piston engine of similar power. Wouldnt the concept be worth a try?
A century later, nothing has changed. There is so much heavy and bulky kit you have to surround your turbine with that it doesn't even make much sense for ships. Today, only nuclear-powered ships are powered by steam turbines as far as I know. For aircraft it is about as practical as the flapping wings.
The topic fits this forum well, for the search for a more practical turbine eventually led to the invention of the pulsejet.
People like Karawodine, Marconnet and Holzwarth were experimenting with ways to power a turbine wheel with the hot gas generated by gasoline vapor explosions, because it was obvious that such a setup would be vastly lighter and more compact than steam. Of the three, only Holzwarth, whose invention did not depend on acoustics, was successful in building a practical turbine, which remained in commercial use until after World War 2 in some cases. Indeed, it was such a good setup that the principle is still being tinkered with.
The other two failed to make anything that was immediately practical. Their ideas were only picked up half a century later by Bertin and associates at SNECMA and developed into jet engines.
Getting the pulsating combustors of the acoustical type to power a turbine was tried by a great number of researchers, as the advantages were glaringly obvious -- Kentfield achieved a 40-percent improvement in engine performance with a 10-percent combustor pressure gain, for instance. But, they all ran into problems of one sort of another, published nice research papers (a very good paper by Kentfield is available from the AIAA) and abandoned their projects in the end.
Re: Steam turbines
About steam turbines being bulky...
Well, yes, if you generate steam by heating it up...
However, what would you say for a turbine being propelled by hydrogen peroxide catalyzed into water and oxygen?
http://en.wikipedia.org/wiki/Hydrogen_p ... propellant
It's also used as oxygen source, if you catch my drift...
Since we're talking turbine, some of resulting water can be chilled and reinjected to further expand the gasses AFTER the oxygen is used up for burning coal dust, aluminium dust, teddy bears... I mean... how many things can you think of that burn in hi-temperature oxygen?
So, a small steam turbine is doable. However, the running costs will be prohibitive. Pure H2O2 is expensive. And corrosive. And requires a dedicated turbine + peripherials. Better solutions exist, so such construction would be done either for fun, or some niche use. but that fun argument is still valid... who said we have to do everything to save money or make money?
Well, yes, if you generate steam by heating it up...
However, what would you say for a turbine being propelled by hydrogen peroxide catalyzed into water and oxygen?
http://en.wikipedia.org/wiki/Hydrogen_p ... propellant
It's also used as oxygen source, if you catch my drift...
Since we're talking turbine, some of resulting water can be chilled and reinjected to further expand the gasses AFTER the oxygen is used up for burning coal dust, aluminium dust, teddy bears... I mean... how many things can you think of that burn in hi-temperature oxygen?
So, a small steam turbine is doable. However, the running costs will be prohibitive. Pure H2O2 is expensive. And corrosive. And requires a dedicated turbine + peripherials. Better solutions exist, so such construction would be done either for fun, or some niche use. but that fun argument is still valid... who said we have to do everything to save money or make money?