and now for some Science..............





Robot

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#1
I posted this question on a Physics forum:

Many years ago I worked on a natural gas pizza oven. The oven had electrodes that measured resistance of the flame. If too high, the oven assumed loss of flame and shut down. This was a safety feature.

My College General Physics text shows a flame distorted by the field from a nearby Van De Graaff Generator.

I can think of many potential applications of altering a flame, perhaps varying the flame spread in an internal combustion engine?

Any other real world applications you know of?

My assumption is different flames = different resistance values

Would an Oxy Acetylene flame be more conductive when rich on oxygen?, or when sooty from lack of oxygen?

Thanks for any input, Regards, John


Here is one reply so far:

Years ago I read of making a speaker using two probes in a flame, connected to a sound source. It is supposed to provide very good fidelity due to the low mass of the flame.
 

Mr Bogus

Trouble Makers Inc.
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#2
seems like the heavy dense gas would be more conductive so a rich (using your term) oxy/acy mixture would have higher resistance.. (actually a "lean" A/F condition")

more acetylene would have lower resistance values? due to the richer fuel mixture?

What I do not see is the ability to force faster flame front propagation electrically..

also in forcing faster propagation (which can be done), you would likely increase the occurrence of pre-ignition or detonation (two separate issues)

what kind of responses have engineers put up on this? is a curious subject..
 

Robot

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#3
seems like the heavy dense gas would be more conductive so a rich (using your term) oxy/acy mixture would have higher resistance.. (actually a "lean" A/F condition")

more acetylene would have lower resistance values? due to the richer fuel mixture?

What I do not see is the ability to force faster flame front propagation electrically..

also in forcing faster propagation (which can be done), you would likely increase the occurrence of pre-ignition or detonation (two separate issues)

what kind of responses have engineers put up on this? is a curious subject..
Here is the link to the Physics Forum, you can see replies as the come in:

Uses for a Conductive Flame

If you google "Flame Speaker" there are some results, but NOT as simple as putting speaker wires in a flame and having a working speaker.
 

Robot

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#6
seems like the heavy dense gas would be more conductive so a rich (using your term) oxy/acy mixture would have higher resistance.. (actually a "lean" A/F condition")

more acetylene would have lower resistance values? due to the richer fuel mixture?

What I do not see is the ability to force faster flame front propagation electrically..

also in forcing faster propagation (which can be done), you would likely increase the occurrence of pre-ignition or detonation (two separate issues)

what kind of responses have engineers put up on this? is a curious subject..
I'm not sure about "faster flame front" but "altered" flame front should be possible, would this have any benefit? Any benefit to altering flame spread for various RPM's?

This is only a question I threw out there, altering the flame is possible, the benefits, if any, are the question.

Obviously spark plug placement/Head geometery affects flame spread.

Would it be possible to deter detonation electronically, so you could run hotter/leaner?

One experiment is worth a thousand calculations , chop 1" off a brigs and stratton cylinder and Ill make a 1" thick gasket embedded radially with coils, we can fire the coils in predetermined intervals to "pull" at the flame and see what happens:thumbsup:
 

AJAY

Registered
#8
Hmm, never heard of this, but did find some interesting stuff in a few minutes of searching.

Flame Triode with Gain: Flame Triode With Gain.

Rev. Mod. Phys. 3, 156 (1931): Wilson - Electrical Conductivity of ...
http://prola.aps.org/pagegif/RMP/v3/i1/p156_1/p156

Phys. Rev. 8, 626 (1916): Ricker - The Electrical Conductivity of
http://prola.aps.org/thumbnail/PR/v8/i6/p626_1?start=0

Haven't read these yet. Suspect that the electrical conduction is from hot plasma and not carbon loading, but then I haven't actually read anything yet.

John, when we do finally meet in person, remind me to tell you about the hyper-fuel efficient engine my friend investigated. This fellow was pestering a certain Agency to the point where they finally sent somebody out to investigate. It relates a bit to your original posting. The actual investigation had life-threatening implications, not once, but twice.
 

Robot

Donating Member
Registered
#9
Hmm, never heard of this, but did find some interesting stuff in a few minutes of searching.

Flame Triode with Gain: Flame Triode With Gain.

Rev. Mod. Phys. 3, 156 (1931): Wilson - Electrical Conductivity of ...
http://prola.aps.org/pagegif/RMP/v3/i1/p156_1/p156

Phys. Rev. 8, 626 (1916): Ricker - The Electrical Conductivity of
http://prola.aps.org/thumbnail/PR/v8/i6/p626_1?start=0

Haven't read these yet. Suspect that the electrical conduction is from hot plasma and not carbon loading, but then I haven't actually read anything yet.

John, when we do finally meet in person, remind me to tell you about the hyper-fuel efficient engine my friend investigated. This fellow was pestering a certain Agency to the point where they finally sent somebody out to investigate. It relates a bit to your original posting. The actual investigation had life-threatening implications, not once, but twice.
Will Do:thumbsup: Sounds like an interesting topic!
 

Robot

Donating Member
Registered
#10
Hmm, never heard of this, but did find some interesting stuff in a few minutes of searching.

Flame Triode with Gain: Flame Triode With Gain.

Rev. Mod. Phys. 3, 156 (1931): Wilson - Electrical Conductivity of ...
http://prola.aps.org/pagegif/RMP/v3/i1/p156_1/p156

Phys. Rev. 8, 626 (1916): Ricker - The Electrical Conductivity of
http://prola.aps.org/thumbnail/PR/v8/i6/p626_1?start=0

Haven't read these yet. Suspect that the electrical conduction is from hot plasma and not carbon loading, but then I haven't actually read anything yet.

John, when we do finally meet in person, remind me to tell you about the hyper-fuel efficient engine my friend investigated. This fellow was pestering a certain Agency to the point where they finally sent somebody out to investigate. It relates a bit to your original posting. The actual investigation had life-threatening implications, not once, but twice.
Incendiary Semiconductor = I'm Lovin it:thumbsup:

Last two links need a password?
 

Mr Bogus

Trouble Makers Inc.
Donating Member
Registered
#13
I'm not sure about "faster flame front" but "altered" flame front should be possible, would this have any benefit? Any benefit to altering flame spread for various RPM's?

This is only a question I threw out there, altering the flame is possible, the benefits, if any, are the question.

Obviously spark plug placement/Head geometery affects flame spread.

Would it be possible to deter detonation electronically, so you could run hotter/leaner?

One experiment is worth a thousand calculations , chop 1" off a brigs and stratton cylinder and Ill make a 1" thick gasket embedded radially with coils, we can fire the coils in predetermined intervals to "pull" at the flame and see what happens:thumbsup:
that would allow us to start the combustion process later... reducing lead time and possible pre-ignition issues.. Could allow for less losses trying to push pistons up against the lit charge..

BUT... the amount of power needed to "run" your coils could easily out strip any power gains unless this only takes a small charge... (have never even heard of this till today so no idea of specifics) sure sounds like a fun project.. :) Engieering guys got some cool ideas for sure... maybe some Obama bucks available to put one together? :O)

I think the pre-ignition could be reduced due to lower cylinder pressures (later ignition timing) Detonation? might get worse.. (does flame front speed affect temp of flame front??) I do not have the engineering knowledge for this part... but I will try anything.. (well once)
 

Robot

Donating Member
Registered
#16
that would allow us to start the combustion process later... reducing lead time and possible pre-ignition issues.. Could allow for less losses trying to push pistons up against the lit charge..

BUT... the amount of power needed to "run" your coils could easily out strip any power gains unless this only takes a small charge... (have never even heard of this till today so no idea of specifics) sure sounds like a fun project.. :) Engieering guys got some cool ideas for sure... maybe some Obama bucks available to put one together? :O)

I think the pre-ignition could be reduced due to lower cylinder pressures (later ignition timing) Detonation? might get worse.. (does flame front speed affect temp of flame front??) I do not have the engineering knowledge for this part... but I will try anything.. (well once)
All good input and questions:thumbsup:

I am continually amazed how the "relatively" simple internal combustion engine keeps getting better and better.
 

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