[Diy_efi] Greenfire spark plugs... thought experiment

[Mike]

ok chaps,

Here tis that simple thought experiment.

Preface.
This is not intended to prove the greenfire plug
works better, its designed to illustrate pressure causing flow
and how this can apply to ignition in a recessed plug. Nor
is it to be taken literally, its indicative of the principle which
I perceive has been glossed over by Adam Wade and I
am hoping will go some way to articulate a reason for
his unwillingness to accept there could ever be such flow.

Whats interesting is once you think over this for a while
and imagine whats going on with some interesting variations
in tube design it might well suggest a mechanism to markedly
improve operation, I'll leave that one for the entrepreneurs...  ;-)

Steel tube 100 units long, say 10 units dia. Closed at position 0
and plunger at position 100 where pressure is to be applied.
Gas 'A' in position range from 0 to 50 and gas 'B' in position
range from 50 to 100. Marked on position 30 where one might
consider is approx position of the exposed end of the high voltage
electrode. The closed end represents the 'blind' end which
Adam Wade has remonstrated about and position 100 is the
open end where gases move to and from.

Now, move the plunger down to position 10.

Q1.     Does the 'mix' line between gas 'A' and gas 'B' also move down
        by same proportion ?
        (rhetorical question - mostly ;-)

Q2.     Is gas 'B' now exposed to the end of the high voltage electrode
        at position 30 ?

Q3.     If gas 'B' is combustible then will it ignite ?

Q4      Can one extend the thought experiment for the converse side
        when there is exhaust from the plug into the chamber following
        (a possible) ignition  ?

However,
One thing that has me a tad curious is the issue of the overall
efficiency and energy of the propogation of the flame front through
the 5 or so peripheral holes - not just the gas, I see no problem with gas
exit, but the actual flame front as I have little conception of the relative
velocities or depth of  thickness or speed of this flame front...

ie.
I understand there is a relationship between the hole
diameter, its material temperature and the issue of pressure differential
across the hole but I recall one safety issue regarding the davy
lamp used in mines in respect of methane meant the flame
front wouldnt propogate [easily]  through a small hole but would
provide visible light, hence its safety value...From what I recall of the
one davy lamp I held at school, the holes were less than 0.5mm, the
holes in the periphery of the greenfire plug are maybe 4 times that etc.

Does anyone know the particular relationship of flame front
size for pressure gradient which allows the davy lamp to
be relatively safe at 1atm yet allow this flame front principle to
propogate through the peripheral holes of the greenfire plug ?


Lets take it from there chaps, I got work to get on with...

cyahs in a few days,


Regards from


Mike Massen
Perth, Western Australia
VL Commodore Fuse Rail that wont warp or melt !
http://niche.iinet.net.au