humid is better in turbines

[jll at edge.net]

I sure hope that the liquid is being flashed off as a gas vapor prior to entering
the combustion chamber. Positive displacement gas compressors tend to come apart
when an incompressible liquid is introduced into the compression chamber.
JL

>KasaRyan at aol.com wrote:
>> 
>> Whoo Whee! opened up a can o worms on this one!
>> 
>> Ok, one of the reasons I put in the explaination I did was that I knew that

>> some early jet aircraft, the 707 among them, would dump hundreds of gallons

>> of water into the combustion chambers of the engines on takeoff.  This
>> probably lowered the temp slightly, but more importantly dramatically
>> increased the volume of what was coming out the back of the engine, and also

>> pushing on the turbine to compress more air.  The more force you chuck out

>> the back, the more the plane goes forward!  Sir Issac had that one down,
as
>> far as Harry ricardo goes, I dont have his book on combustion chamber design,

>> but I do believe he plugged away at it for a while.
>> 
>> Roger, you seem to have the thermo book handy, so I would like this
>> calculated.  If you have one gram(or cc) of water at 100C, and you add enough

>> energy to vaporize it into gas, how much energy does this take, and at 1
ATM,
>> how much volume does it take up once vaporization is complete?  If you take
1
>> cc of air at 100C, and you add the same amount of energy, is the resulting

>> volume increase more or less than for the water which goes thru the state

>> change.  (IS this PV=nRT? or something of that sort)
>> 
>> I believe I was wrong on the water being in a liquid form on a humid day,
but
>> what if you use injection, and have liquid water in the combustion chamber.

>> 
>> If this goes on too long, i will probably have to dust off the books and
look
>> it up myself.
>> 
>You might need to, I won't be able to run the numbers until tonight.
>
>I believe you have 2 test cases, all closed systems, I don't believe
>humidity enterns in to it as water vapor acts as an ideal gas.
>
>	case #1: 1 mole an ideal gas at 50C with xx joules then 
>		added to it what is the ending pressure.
>	case #2: 1 mole (minus a small amount for the water) of an ideal
>		gas and 1 mole of water (18ml) at 50C with xx joules added
>		to it, what is the ending pressure?
>
>I suspect strongly case #2 (same physical volume starting) will produce
>a higher ending pressure, this requires that you get the water into the
>combustion chamer as a liquid, and then add enough energy to convert it 
>to an ideal gas.    If it goes inth the combustion chamber as a gas, it 
>will act pretty much like an ideal gas, and no gain is made, and also it
>would have displaced some oxygen coming in so reduced the amount of energy

>that you could add to things.   I am pretty sure the Harrier jets do
>this trick also to increase thrust, though only for short periods of time,

>I suspect that the water is weight inefficient so you don't want to use
>it for long times (only use to hover (harrier) and takeoff and other
>emergencies).
>
>				Roger
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