Ancient History

[Jonathan Lloyd]

In message <Pine.SUN.3.91.960903082022.12519C-100000 at pioneer.uspto.gov>,
Dirk Wright <wright at uspto.gov> writes
>On Mon, 2 Sep 1996, Robert J. Harris wrote:
>> 
>> Liquid fuel does not burn - period.  It must be vaporized before it burns.
>
>Um, sorry. Gasoline vapor explodes, it does not burn. Liqiud gasoline 
>burns. Gasoline vapor ignited in a combustion chamber will cause 
>
>****************************************************************************
>Dirk Wright                                                wright at uspto.gov
>
Excuse the butt in but liquid fuel does burn, try throwing a match into
a bowl of gasoline, and vapour does not neccessarily "explode".
The chamber will be full of vapour and droplets of various sizes prior
to spark.  As the temp and pressure rise the oxygen in the air
dissociates ( a very temp dependent effect) and provides the oxygen
radicle neccessary for combination with the hydrocarbon mix.  Explosion
occurs when the temp is high enough to dissociate the hydrocarbons and
is a function of "quality" i.e. octane rating in which case the whole
cylinder contains free oxygen and free hydrocarbon radicals and the
whole lot reacts at once.  Bad news , knock , damage etc.  The fuel
should be a high enough octane rating to suppress dissociation.
Reaction is then totally determined by the spark and a flame front is
created.  What is wanted is not the fastest burn possible but a good
start and prolonged long enough to finish some way down the power
stroke.  The flame speed of the vapour for a given mixture is
calculatable and reaches the cylinder walls quickly igniting the
droplets as it goes.  They continue to burn and any droplets too big
will be exhausted without having provided all the power they could have
done.
-- 
Jonathan Lloyd     john at anergy.demon.co.uk