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Old 05-09-2016, 05:07 AM   #11 (permalink)
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I'm thinking that sure, it'd increase back pressure and actually hurt performance during use, but not enough to damage anything...
vs

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I've read in other gas engines where exhaust water injection is used to create a reflective wave which dynamically "tunes" the exhaust system (via exhaust gas scavenging) to improve torque and horsepower at rpm bands other than what the original system was designed for.
Did anyone bring popcorn?

Steam for lift

Hydrogen gas has a standardized lift of 11.19 N/m3. Helium has 10.36 N/m3 lift, while hot air varies from 2.7 to 3.2N/m3. Pure steam has 6.26 N/m3

Find an article on the relative merits of the various lifting gases, including losers like methane and ammonia at Steam Balloon JBFA Article

'Steam' power

The world's tiniest [theoretical] engine uses water as a working fluid, but without the phase change:

https://www.washingtonpost.com/news/...allest-engine/
Quote:
The University of Cambridge engine needs a bit of refining before it can be hitched to a nanoscale object. “Our main challenge is how to build a device that harnesses the forces for motion in one direction – a bit like a piston on a steam engine,” Baumberg wrote. “Currently the force just expands and contracts in all directions.” But a few steps down the line — once the directional problem is solved — he envisions “tiny nanomachines that can walk around, controlled by beams of light.”

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Old 05-10-2016, 12:37 AM   #12 (permalink)
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Originally Posted by freebeard View Post
vs



Did anyone bring popcorn?

Steam for lift

Hydrogen gas has a standardized lift of 11.19 N/m3. Helium has 10.36 N/m3 lift, while hot air varies from 2.7 to 3.2N/m3. Pure steam has 6.26 N/m3

Find an article on the relative merits of the various lifting gases, including losers like methane and ammonia at Steam Balloon JBFA Article

'Steam' power

The world's tiniest [theoretical] engine uses water as a working fluid, but without the phase change:

https://www.washingtonpost.com/news/...allest-engine/
Kinda not sure where you were going with that, but here's an article on a two stroke racing bike with a water tuned exhaust. Got no idea if it'd work in a 4 stroke gasser or diesel, but interesting nonetheless.

http://www.saltmine.org.uk/randy/h2o-injection.html
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Old 05-10-2016, 12:49 AM   #13 (permalink)
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Twice the lift of hot air, and it's dynamic for buoyancy control.

OTOH Bucky Fuller's Cloud Nine cities used one degree of temperature difference inside a one-mile sphere.

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Fuller suggested that the mass of a mile-wide geodesic sphere would be negligible compared to the mass of the air trapped within it. He suggested that if the air inside such a sphere were heated even by one degree higher than the ambient temperature of its surroundings, the sphere could become airborne. He calculated that such a balloon could lift a considerable mass, and hence that 'mini-cities' or airborne towns of thousands of people could be built in this way.
https://en.wikipedia.org/wiki/Cloud_Nine_%28tensegrity_sphere%29

Steam in ballonnettes could control altitude.

drrbc -- cross-post. I just wanted to post that old cartoon and mock it; where it goes from there is open (nanomachines?) but hopefully steam related.

I'll check the article.

Edit:
What do you think? He uses an equation that he doesn't give, and suggests the Vs (I assume velocity?) drops from 1700 to 1440fps. Which suggests a smaller volume over time, but steam is going to expand the volume.

I can see reducing radiant heat off the pipes to keep velocity up, that's why thermal wraps. This maybe uses heat of vaporization to reduce the energy in the gas so it doesn't heat up the pipe it's passing through, instead.

I don't know why it would be limited to two-strokes; but what's the advantage over injecting the water into the combustion chamber?

Last edited by freebeard; 05-10-2016 at 01:12 AM..
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Old 05-10-2016, 02:59 AM   #14 (permalink)
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drrbc -- cross-post. I just wanted to post that old cartoon and mock it; where it goes from there is open (nanomachines?) but hopefully steam related.

I'll check the article.

Edit:
What do you think? He uses an equation that he doesn't give, and suggests the Vs (I assume velocity?) drops from 1700 to 1440fps. Which suggests a smaller volume over time, but steam is going to expand the volume.

I can see reducing radiant heat off the pipes to keep velocity up, that's why thermal wraps. This maybe uses heat of vaporization to reduce the energy in the gas so it doesn't heat up the pipe it's passing through, instead.

I don't know why it would be limited to two-strokes; but what's the advantage over injecting the water into the combustion chamber?
Well hell, I wasn't actually planning on re-reading the damned article- I was just pretending this was important so that sadistic physical therapist would quit trying to rip my arm off for a second.

But yeah, that sounds right. Despite the 1700X volume increase for turning water into steam the temp at 9,000 rpm went from @ 700ēK down to 425ēK, so I'm guessing you could assume a lower speed of sound. From that calculate the distance from the port needed to have the rarefaction part of the exhaust pulse wave "pull" the exhaust gas out.

So just off the top of my head, I can see some improvement in a 4 stroke gasser, just less than a two stroke. As in the two stroke the intake charge is being pulled into the cylinder as the exhaust is being pulled out. Not so in a 4 stroke. So I'd expect 50% less power improvement per cycle, but I also suppose I could live with 12% more midrange HP or torque. Could be better in a diesel though.

As far as just injecting into the cylinder that sounds a bit complex for the DIY'er. My uncle said it worked great on those 2,200 hp aircraft engines when they'd double the boost from the supercharger. He said they were able to get the hp from @2200 up to 2800 which would allow them to get an overloaded aircraft off the ground in the hot thin air.

But it sounds like to tune the exhaust all you really need is a measuring tape and a drill. (Well, maybe a valve. And a rpm sensor. A water reservoir. A pump too. OK, maybe a bit more than just a drill and a tape measure- but you get my drift.) It should be doable by someone mechanically inclined (not me certainly!).

Anyway, it was just a thought.
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Old 05-10-2016, 01:35 PM   #15 (permalink)
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Old 05-10-2016, 07:07 PM   #16 (permalink)
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...As in the two stroke the intake charge is being pulled into the cylinder as the exhaust is being pulled out. Not so in a 4 stroke. ...
Actually, many 4-stroke engines have intake and exhaust overlap, where both are open at the same time for a bit. This is especially so in higher-performance engines, though they generally don't go as far with it as 2-stroke ones do.

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Old 05-10-2016, 11:33 PM   #17 (permalink)
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ConnClark -- Always interested in your input (anyone who identifies as Gamera is Okay by me); but I was not expecting that. Which is a good thing. It reminds me of Little Toot (a kid's book).

So how about this: In another time and place, maritime regulations required a licensed steam engineer onboard at all times. This made a grocery-getter impractical (unless self-licensed):

https://en.wikipedia.org/wiki/Naphtha_launch

Voila! an aluminum-hulled naptha-powered launch with really nice lines in 1892:


Yes, that Alfred Nobel. Re: 2-stroke:
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A single rotating overhead camshaft ran above the cylinders, parallel to the crankshaft. Eccentrics on this shaft actuated a transverse slide valve for each cylinder. The valve camshaft was driven at engine speed by gears from the crankshaft.
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Old 05-11-2016, 03:40 PM   #18 (permalink)
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When I was very young my Dad made one of these little boats out of a small piece of copper tubing (IIRC).

Of course it's gone now and I didn't appreciate it for what it really was. But I think he made it not just for me, but for himself some as well. I remember the small burned out candle he put in a bottle cap to power it. He and my uncle played with it quite a bit on a vacation we took at a lake in Canada.

Now if I could only remember where I put my keys...
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Old 05-11-2016, 10:33 PM   #19 (permalink)
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Out of sight, out of... Hey! Squirrel!

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