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Principle of Operation: a film of water coating the inside of the combustion chamber flashes into steam which provides extra motive power and keeps the engine relatively cool. The cylinder and crankcase are water-lubricated. The superiority compared with existing water-injection methods is that the
film of water is directly deposited onto the combustion chamber components instead of being sprayed. This and water lubrication of cylinder/piston/crankshaft allow for a 2-stroke cycle (instead of 4 or 6) which of course means a higher hp:weight.
How it Works: the cylinder is bigger than the piston... okay I'll grant you that's usually the case in engines that actually run, but in this case the gap is (relatively) big. Near the bottom of the cylinder a ring of injectors continuously force water into the gap. The very bottom portion of the cylinder narrows back to a normal (lack of) gap: we don't want water flowing this way except a small amount for lubrication.
On the upstroke, water is filling the gap. The downstroke leaves a film of water behind on the cylinder walls. At BDC water starts to cover the piston head and the movement back up to TDC completes it. Just to make sure everything's coated, the cylinder-head and valves are hollow, surfaces perforated; water constantly seeps out under pressure.
By the time the fuel combusts, the entire chamber and soon-to-be-exposed cylinder sides are covered in a film of water; just enough to convert all that nice heat into steam. Very little heat is lost through the insulated walls. The exhaust passes through a very robust turbocharger/turbine to condense the water which is then filtered and recycled.
For simplicity of explanation purposes we've been using a constant-rpm engine operated in a warm climate. A cold climate would require an insulated temporary water storage/pre-heat system, and non-constant rpm requires variable pressure water injection.
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Annotation:
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The advantage over existing water-injection methods is that the film of water is directly deposited onto the combustion chamber components instead of being sprayed. This and water lubrication of cylinder/piston/crankshaft allow for a 2-stroke cycle (instead of 4 or 6) which of course means a higher hp:weight. |
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[phoenix] re <link>: that's mine :D and apart from the perforated cylinder head, they're different with different purposes: this one demonstrates a new-and-much-improved water deposition method: a (relatively) simple conversion for an existing air-cooled engine. The other one's main point is to use an oxygen-enriched atmosphere (resulting in a reduced compression ratio) and to replace nitrogen with water as motive force. |
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[edit] I played the shell game with Titles a bit and had to delete your <link> since when I was finished it linked back to this post... from this post... sorry. |
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I see what you're trying to do in terms of cooling the cylinder walls (worth a bun), but mixing oxygen, water and steel seems like a bad idea to me (fish), and you're attempting to put an awful lot of pressurized holes in already highly stressed components (fish). |
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Also, the surface area available and control afforded by explicitly injecting the water probably explain why this hasn't been tried yet! |
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I would suggest using a light oil that would evaporate in a similar fashion to that of the water without bringing the corrosion problems, but it would probably combust! |
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//cooling cylinder walls//
actually I'm keeping the cylinder walls from getting hot... not the same thing at all. |
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//mixing oxygen, water and steel seems like a bad idea//
stainless? nickel-plate?... it only has to put up with, at most, a couple hundred C. |
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//pressurized holes in already highly stressed components//
if you're referring to the perforated cylinder head, the duct(s) inside are filled with nice non-compressible water. The only component that I see as having to be unusually robust is the turbocharger/turbine. |
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//light oi//
Water is used as lubricant in steam engines, and using an oil might cause HC emissions in a 2-stroke.(note that this is not a "chainsaw 2-stroke" design that mixes fuel and oil in the crankcase) |
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//Also, the surface area available and control afforded by explicitly injecting the water probably explain why this hasn't been tried yet!//
explain. |
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Now what I'm *not* sure about is a non-uniform combustion resulting in an off-centre stroke (because of the watergap) but since that kind of thing would be a consistent non-uniformness a slight offset can be built-in to compensate. |
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Another concern is how to get that steam back to water for recycling: sure there's going to be excess water in the system from the combustion, but I need(want) to grab at least enough for recycling directly after the exhaust turbine/turbocharger is through with it. |
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And of course the power-stroke would be different since steam is being formed during the stroke as well. |
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