Hi Viv,
I'm not sure which turbine you are talking about for the 100 shp figure, so it's hard to talk about comparisons between compressor turbines and pulsejet turbines in that example.
I naturally do think that one can describe the action occurring in a pulsejet attached to a turbine as taking the place of the compressor (and combustion chamber, as well) -- since I did in my last post
. However, a better analogy of the compressor type than a fan compressor is a piston type, with somewhat leaky acoustic driven air valves and pistons.
And in the sizes of a few kilowatts may have many advantages over a shaft driven compressor (true microturbines) for stationary engines. I have little doubt that the large aircraft turbojet engine as we know it will NOT generally be replaced by a pulsejet as we know it -- at least without an alteration in the nature of the physical world. Always a possibility either by fundamental discovery or external manipulation, but so far, remote in this field.
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One of the current fundamentals of a turbojet aircraft engine is that the turbine's purpose is to turn the compressor. If we didn't need a compressor, we probably wouldn't need a turbine on an aircraft. A turbine can be viewed by an irreverent person (certainly not me...) as a kludge for the compressor. I'm of course excluding turboprop engines, which do absorb power from the turbine beyond compressor requirements.
In a stationary engine however, a turbine is the transmission between air flow and shaft power for whatever external purpose we have in mind. Because it can be run from a pulsejet, a mechanical compressor is not required. It becomes a pure transmission, and that transmission can be optimized to output requirements rather than compressor requirements. This is a big deal, I think. Not only elimination of the compressor power draw but a reduction of transmission losses.
I don't have any proof -- just a suspicion so far. I have constructed a frighteningly crude turbine
And I have no illusions that it could not be bettered by a monkey with welding gear and a little training. The blade shapes, bearing types, materials, housing, inlet and exhaust shapes probably couldn't be much worse, and the "scientific" assumptions, "calculations", and certainly, my incorrectly built version of a low thrust pulsejet could probably be improved upon by 95% of the readership of these forums. Sorry, I don't mean any connection between the monkey analogy and the readership -- maybe I should put that in a separate paragraph.....
But anyway, I remain hopeful that better minds will certainly be able to exceed my own performance envelope.
Now Reynst, because I love to think about, and often question, that engine type. Hope you don't mind our discussing it a little more deeply here as a turbine driver.
A Reynst engine as commonly referred to here in these forums seems to be a lot of different things. Mostly it is viewed as a tapered pot type engine with a single orifice and an internal focusing ring and lip feed. Drawings of a Reynst often show some other elements that seem to me to be rather critical. An intake manifold, a deflector shield, and a diffuser cone exhaust. Though concentration seems to be on building the pot with internal ring and attempting lip feed occasionally -- (these ARE logical building blocks because they are what is typically thought of as an engine) -- the intake manifold, deflector, and cone are usually missing.
The result is kind of like taking a 2 cycle engine and removing the same items -- intake manifold, ports, and tuned exhaust, and trying to get it to run briefly by squirting fuel into the cylinders. Yes it is an engine, and may run for a moment...but....
What I'd like to suggest here is that the lip feed and manifold, deflector, and diffuser cone are the entire fuel induction system. They cannot be separated. The cone and deflector and manifold must all work together to get a charge into the Reynst. Fuel and air will not flow (in appreciable amounts, or possibly at all) without the suction created by the cone, and the cone suction and timing is dependent on the acoustic energy from the exhaust. So, eliminate the cone and you don't draw the the quantity of air and fuel into the engine through the intake manifold.
If you keep it, unfortunately, sticking a turbine on top of the cone, as I did fairly easily with the draft pulsejet exhaust, probably isn't practical. The outlet is wide, meaning that you would need an axial rather than radial fan. These in my opinion will seriously interfere with pulsing and flow, and the typical vanes and blades will also perform poorly with that flow.
Not saying it will be impossible, but from here it looks hard to imagine as operable.
No problem is too small or trivial if we can really do something about it.
Richard Feynman
the huge shaft horsepower required to spin up even a small compressor wheel normally comes as bit of a shock to people.
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