Re: Surge on GE90

From:         bauwens@acs.ucalgary.ca (Luc Bauwens)
Organization: The University of Calgary
Date:         22 Jun 95 03:07:31 
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In article <airliners.1995.838@ohare.Chicago.COM>,
 <nak@gwe486.cb.att.com> wrote:
>In article <airliners.1995.773@ohare.chicago.com>,
>Wayne Dockery <wdockery@pipeline.com> wrote:
>>
>>I have a question... When an engine such as the GE90
>>is starting, what controls which direction the combusted
>>material is expelled from the combustion chamber?  I guess
>>the fan is electrically spun-up with "starter", but when
>>ignition first takes place as in any "explosion", how do
>                                       ^^^^^^^^^
>First off, it's combustion, not an explosion.  Explosions involve
>supersonic shock waves, combustion does not.

I wish people who want to argue semantics would stop and convince
themselves that they know about what they are talking about before
getting into the fray :-).

"Explosion" means effectively anything.  It is a loose word that can
be used to describe any combustion process that's reasonably fast.
It certainly does not imply anything substantial in the way of shock
waves etc.

The word "detonation", however, refers specifically to a very
fast combustion, in effect, a flame riding on a shock wave.  And
to describe an explosion that's not quite that fast, there is the
word "deflagration".

Luc

--
Luc Bauwens                        bauwens@acs.ucalgary.ca
The University of Calgary,         Department of Mechanical Engineering
Phone: (403) 220 5792	           Fax: (403) 282 8406
http://www.ucalgary.ca/~bauwens/