Gabriel From Germany, joined Dec 2005, 0 posts, RR: 1 Posted (12 years 9 months 1 week 2 days 11 hours ago) and read 2258 times:
Hi,
I ever heard about the water injection system to increase the engines power in take off (such as in the Boeing B52 Stratofortress), but never knew hod does it work...
Jt8djet From United States of America, joined Jul 2000, 212 posts, RR: 0 Reply 1, posted (12 years 9 months 1 week 2 days 10 hours ago) and read 2179 times:
"The injection of water into the gas path causes heat transfer. When the fluid evaporates, heat in the air will be transferred into the fluid droplets, cooling the air and making the gas flow more dense. Water injection in a gas turbine engine is then a means of augmenting engine thrust. Augmentation can be thought of as occurring in two ways. First, addition of water to air in the compressor increases compression and mass flow. second, water cools the combustion gases which allows additional fuel to be used without exceeding maximum temperature limits during takeoff. Increases in these three engine parameters results in a thrust increase in the range of 10 to 15 per cent." - taken from Aircraft Gas Turbine Powerplants Handbook.
Buff From Australia, joined Mar 2007, 0 posts, RR: 2 Reply 2, posted (12 years 9 months 1 week 2 days 9 hours ago) and read 2162 times:
Sometimes referred to as "Water-Meth" (Methanol) or "Wet Take-Off Power". The methanol is included as an inert agent to prevent the water from freezing, either in the tank, or during the heat transfer referred to above.
A few years ago in northern Manitoba, Canada, an HS-748 was getting ready to depart a small strip. Normal procedure is to arm the water-meth injection prior to throttle up. In this case though, the arming wasn't done until late in the takeoff roll or just after airborne (I can't remember the specific details). Unfortunately, when asked to fuel the airplane earlier, the new fueler mistook the water-meth tank for a fuel tank.
When the kerosene entered the compressor section of both engines, one flamed out, the other exploded in the exhaust section. The plane was deadsticked into a dry river bed with no serious casualties.
Prebennorholm From Denmark, joined Mar 2000, 6019 posts, RR: 55 Reply 3, posted (12 years 9 months 1 week 2 days 9 hours ago) and read 2140 times:
Also early 747 clasic airliners had the ability to use water injection. It was only used occationally under hot&high conditions, or at MTOW on marginally short runways. I don't think it is used any more on commercial planes. It gives a terrible smoke.
Also piston engines have used water injection. Especially during WW2, but also later carrier fighters etc.
We are not talking about a few bottles of water. A B-52G could carry 10,000 lbs of water for take-off. It would last only one and a half minute, so the party ended at about 200 feet altitude.
Best regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs, Preben Norholm
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From Germany, joined Dec 2005, 0 posts, 
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