Is water injection a redundant technology?
 

Apologies for going over an old subject, couldn't find a suitable old thread to resurrect that wasn't closed.

I'm doing some work on a course manual which must include water injection systems but, whilst I understand how they work, am beginning to question the relevance of the subject (as a thrust augmentation mechanism) to todays aircraft. I know the Harrier has a water injection system but understand that later evolutions of the Pegasus are sufficiently powerful as to be able to operate without water injection at all.

So, does anything still use water injection, or water/meth injection as a thrust recovery/augmentation system or am I simply recounting history.

Many thanks

Even the latest mark of Pegasus (Mk 107) fitted to the Harrier GR7 and will be fitted to the GR9 has Water Injection and uses it!

Opening myself up for more criticism - I believe the Fokker F27 still uses Water Injection too - Water tank is up in an engine nacelle (- Not to be confused with the fairly similar looking F50, mind!)

Don't the B-52 and some KC-135s still rely on water injection, too?

Rigga you are correct the F27 has water injection.

http://answers.yahoo.com/question/in...7085218AAMuU7p
[quote]

Source(s):
Former AF "SAC Trained Killer", working in aircraft maintenance.

Thanks guys,

With respect to turbojets I think the key phrase is 'used to be used on'. Other than the Harrier, I cannot find another current application of water injection in a jet, although some props do still seem to have it.

Those "Props" have Jet engines too, and use water in exactly the same way as High-Bypass Turbofans, for Hot, High or Heavy performance enhancement. (Does that sound too "Engineery"?)

Water injection is still used daily on the Pegasus engine, but purely to cool the engine, not to increase thrust in the same way that other water injection systems operate.
Hope this helps.

Water injection. RR Dart
 

Although the Dart is not a modern engine there are still a few around, the injection is a water methonol system for use during take off.
The mixture is water 63 per cent, methonol 37 per cent plus Pyrodine at 0.5 % by weight, ( usually purchased ready mixed)
The system can be a power restoration system, (F27), where by the power is increased to the rated take off power, or boosted (Herald) where the power is inceased from a "dry" torque to a "wet" torque. This is achieved by simple adjustments to the water meth control unit, and these are set during the engine installation process.
The mixture increased the air density and adds more fuel, the aircraft that operated at max take off weight ie freight operators, tended to use water meth every time.

Regards,
om15.

Thanks rigga,

Yep, i realise that a turboprop is a torque producing gas turbine and that water injection can be used in the same way is it is/was on a jet.
It does seem though that, Harrier aside (which I used to teach as a propulstion instructor on the Harrier Maintenance School; GR3 and T4 vintage :\ ) water injection now only appears on some older turboprops although it may have a use as an omissions reducing method.

Harrier water injection
 

Latearmlive,
Water injection does cool the Mk107 engine in high temps, which then allows you to pump in more fuel to gain more thrust!;)

Drifting off topic slightly, I seem to remember the DC6 (P&W R2800) used an Anti-Detonation Injection fluid that included a small percentage of fish oil to keep the valve gear/guides and piston rings adequately lubricated.

The leaky engines then kept the airframe lubricated.

Water injection
 

Dont forget the Andover !! Believe a couple still flying from a very long runway in wiltshire !!!! I believe some of the early 747 - 100 's with P&W JT 9'S but deleted a long time ago .

I'm surprised that pyridine (used as a denaturant to deter people from drinking the alcohol) is allowed in methanol for gas turbine use. I recall reading (can't remember where) that it is harmful to hot nickel alloys.

DEF STAN 01-5 ( http://www.dstan.mod.uk/ ) makes no allowance for it in AL-14 (Methanol) nor AL-28 (Water Methanol 44/56); and both specify "colourless"

Used to fly a civil BAC111 (500 series) which had water injection. Very useful for getting airborne from Naples with a full charter pax load on a stinking hot day. I don't know where the aircraft is operating now, if at all. RR Spey engines IIRC.

True, what I was getting at was that it is not the water that increases the thrust (by increasing the mass flow rate), but the cooling effect it brings that allows (as you say) the engine to run hotter/faster.
You can get the same thrust without using water (as I'm sure you know) but the engine life would be rapidly reduced!:O
Cheers
LAL

Golf Bravo Zulu,
regarding the pyridine ( please excuse original spelling) additive to the water meth mix, this info originated from a Handley Page Maintenance Manual circa 1970's. The mixture came in 50 gallon drums ready mixed, so I have no experience of the contents. There are a couple of spec.references that I have come across, RR Spec MSRR9859 and D Eng RD2491, but as yet I haven't found the documents.
Any boffins out there with the answer?
Regards
om15

So, getting back to the original question... leaving old designs still in use (Pegasus, TF-33, etc.) aside, do any turbojet/turbofan engines designed since ~1970 use water injection? :rolleyes:

This includes F-100-PW, F101/110-GE, RB.199, etc., but not new versions of old engines.

How about those designed since ~1985?

9/06/1971 Pan International. BAC-111 Hasloh, Germany The aircraft collided with a bridge, shearing off both wings, after a double engine failure occurred during takeoff. The water-injection system to cool the engines during takeoff was inadvertently filled with kerosene instead of water.