<VV> [fastvair] Adding Water to the Combustion Cycle

[Michael Kovacs]

Frank is right. 
 The stuff I use to put into the big radial engine acft was called ADI (anti 
detonation injection). We mixed it up by the hundreds of gallons. It was 49% 
water 49% alcohol and 2% water soluble oil. With the big recips  using high 
boost to take off on a hot day, the purpose was to keep detonation from 
occurring which can result in a loss of power and possible engine damage. 



 Reducing the possibility of detonation actually increases the horsepower under 
boost. I believe the engine designers of the big recips understood this. However 
you have to get to the situation of destructive detonation to have the ADI work 
for you.

MIKE KOVACS




________________________________
From: "FrankCB at aol.com" <FrankCB at aol.com>
To: fastvair at yahoogroups.com; gadkinsj at yahoo.com
Sent: Fri, September 30, 2011 1:49:15 PM
Subject: [fastvair] Adding Water to the Combustion Cycle

  
Jerry, 
The injected water does a lot more than simply "cool the engine".  It  actually 
takes part in the chemistry of combustion of the hydrocarbon  gasoline.  As Sir 
Harry Ricardo pointed out many decades ago, using water  injection actually 
reduces MAXIMUM combustion pressure (that breaks things)  while INCREASING the 
AVERAGE combustion pressure that makes TORQUE (engineers  call it BMEP).
 
Here's only one of many references you can follow:  
http://www.eng-tips.com/faqs.cfm?fid=811 
 
Over 20,000 of our fighter aircraft used water injection during WW2 and  most of 
these planes already had turbochargers/superchargers as well  as inter/after 
coolers.  Pratt and Whitney even carried out  supplying water injection to 
piston-engined commercial aircraft after WW2.   Quoting from their 1947 brochure 
"Water Injection for Commercial  Aircraft":
"Pratt & Whitney Aircraft has developed the war-proved Water Injection  System 
for application to the Double Wasp and Wasp Major engines installed in  
commercial aircraft.  The use of water injection permits the safe increase  in 
take-off horsepower by as much as 15%.......(This) is a fully developed and  
proved product.  Over 20,000 fighter aircraft were provided with this power  
augmenter during World War II and the additional performance made available  
played a significant role in maintaining air supremacy."
 
The fact that water injection can significantly eliminate pinging and  
detonation even in NON-boosted engines shows that its effects extend far beyond  
simple cooling of the A/F mixture before combustion.
 
Frank "chemical engineer" Burkhard
Boonton, NJ
 
 
 
In a message dated 9/26/2011 10:30:38 A.M. Eastern Daylight Time,  
gadkinsj at yahoo.com writes:
I also    challenge Adding water to the Combustion cycle.  It is true that it 
will    help to cool the engine but that is because the Temp in the combustion 
chamber    doesn't climb as high thus lowering the effective power available to 
the    engine.  I am of the opinion this would be a zero game with respect to    
Heat, and a loss with respect to volumetric efficiency as you are doing work    
to compress something that doesn't give you any work in return. 

>
>