[Gasification] Underwater gasification?

[linvent at aol.com]

An interesting aspect of propulsion is that the engine combustion 
process cannot exceed the speed of sound. On the SR-71 Blackbird 
engines, there are intake cones in the engine cowling which slow down 
the air speed so that it would combust in the engines. I understand 
that in the early ones these were manually shifted in and out and could 
lead to flame out if not set right. Now, if the engine exhaust is 
slower than the supersonic speed that the aircraft is traveling at, how 
does it move supersonic? The same is stated for rockets, particularly 
if they are moving near the speed of light. The SR-71 still has 
classified top speed and altitude.
Tom Taylor

-----Original Message-----
From: Daniel Chisholm <dmc at danielchisholm.com>
To: Discussion of biomass pyrolysis and gasification 
<gasification at lists.bioenergylists.org>
Sent: Sun, May 22, 2011 5:52 pm
Subject: Re: [Gasification] Underwater gasification?

A Humphrey-inspired water jet is an interesting idea.

FWIW I don't think it would be an efficient means of low speed marine 
propulsion though; it would suffer from low propulsive efficiency 
because the jet velocity would be too high.  The efficiency of a 
reaction engine (which is something that generates thrust by 
accelerating and expelling mass - a very broad category that includes 
not just jet and rocket engines but also propellers on aircraft and 
ships) depends on the speed at which the mass is expelled. 
 Accelerating a small mass to a large speed, is not as efficient as 
accelerating a larger mass to a lesser speed.  If you look at aircraft 
jet engines today (high bypass ratio turbofans) you will notice that 
they are much larger in diameter than the jet engines of the 1950s 
(turbojets) - this is why.




--
- Daniel
Fredericton, NB  Canada_______________________________________________
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