From: cdorrough@spamspamgormna.com.au.retro.com   
      
   "toby"  wrote in message   
   news:GubMb.3338$OA3.680556@newsfep2-win.server.ntli.net...   
   > I looked on the web curious about thrust augmentation concepts for jet   
   > engines and found a 1952? NACA report that detailed an experiment where   
   > water was injected into the combustion chamber to increase mass flow and   
   so   
   > thrust.   
   >   
   > However, the water and fuel were injected separately and the researchers   
   > limited themselves to only adding 20% (I think) water because they thought   
   > it would start interfering with combustion stability or something.   
   >   
   > Has anyone heard of any research into pre-mixing the water and fuel   
   together   
   > to avoid this problem?  Or any other similar research like running jets on   
   > water-alcohol fuels, or water-oil emulsions to achieve the same effect.   
      
   Hi, Toby.  Water is the most common contaminant found in jet fuel and can   
   cause icing in aircraft fuel systems and corrosion of fuel system   
   commponents - so it's best not pre-mixed with the fuel at all or for any   
   length of time.   
      
   There are a few things that *are* commonly added to jet fuel:  eg. F-34   
   AVTUR (air force grade)contains small amounts of FSII (Fuel System Icing   
   Inhibitor), ASA (Anti-static Additive) and some kind of lubricity improver   
   to help things along and common-or-garden JET-A1 is the same stuff minus the   
   FSII.   
      
   To answer your question, water injection (either straight de-ionised water   
   or a DI water/alcohol mix (50/50, IIRC) ) is still used occasionally on some   
   freight/commercial aircraft to increase thrust on take-off.  It is stored in   
   a separate tank on the aircraft and is injected directly into the combustion   
   chamber as required.   
      
   With the ever-increasing efficiency of modern turbo-fan engines, the need   
   for this sort of thust enhancement is waning dramatically, so it would not   
   surprise me to hear there has been no further research on this subject.   
      
   I hope this helps.   
      
   Cameron:-)   
      
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