Injecting water into an engine?

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Eric
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Re: Injecting water into an engine?

Post by Eric » Tue Oct 07, 2008 10:39 pm

Hey,
I dont spend much time on the forum especially the valved section anymore.

Water injection can be done at the intake when you use fuel like propane, without any preheating, and just using the engine to carburize its own water, you can get water consumption rates of over 3 gallons a minute before the engine will quit. With methanol mixed in its even higher. This isnt the best way but it will work.

Spraying water into the combustion chamber with an atomizer nozzle can have good results, if you inject it farther down the tail it will absorb a lot of waste heat but in effect will make it harder for the engine to push exhaust out the tail, where flash vaporization in the combustion chamber results in higher pressure in the right place and higher maximum performance.

You can preheat the water before you inject it but have to be careful not to preheat it too much so it doesnt come out of the nozzle as steam.

For planes it wouldnt be good because they can consume sooo much water per minute, a boat would be great.

Eric
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Mike Everman
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Re: Injecting water into an engine?

Post by Mike Everman » Wed Oct 08, 2008 12:05 am

Thanks, Eric! That was what I was wondering about. Glad you found your way to this thread.
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Eric
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Re: Injecting water into an engine?

Post by Eric » Wed Oct 08, 2008 4:35 am

Forgot to add ' 3 gallons per minute on a 12 lb chinese valveless' Still an enormous flow rate compared to the fuel flow rate.

Eric
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Re: Injecting water into an engine?

Post by Mike Everman » Wed Oct 08, 2008 1:45 pm

Were you watching thrust during that?
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dynajetjerry
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Re: Injecting water into an engine?

Post by dynajetjerry » Fri Nov 21, 2008 4:55 pm

Hi, Guys,
A comment on this subject, if I may:

For those who have seen the IMax "Fires of Kuwait," you might recall a sequence showing a Rumanian (I think,) fire crew who used a big fighter jet engine to quench some of the fires. They injected an enormous amount of water into the exhaust of a full-thrust jet and, literally, blew out the fire as well as cooled the hot plumbing. It was extremely effective and very impressive.

Of course, this added mass and thrust, though that result was not discussed or explained. Also, engine operation was affected very little because the water was injected in the exhaust duct rather than inside the engine.

Just wanted to tweak your memories.

Jerry
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