Science paper on pre-chamber or flame jet ignition.

[godlameroso]

https://www.sciencedirect.com/science/a ... 1117302284

Found this interesting, goes over things we already know and a few new insights.

[johnny comelately]

https://www.sciencedirect.com/science/a ... 1117302284

Found this interesting, goes over things we already know and a few new insights.

there must be a crossover point where science/simulation is more practical,ie, large complex jobs but for this its easier to turn some bits up and stick them in and see the wow factor. best part is changing the 'barrel' size and watching the flame pattern across the crown change.

[godlameroso]

They tried different barrels, I though the paper was educational as to the different configurations that have been tried over the years, and who tried what and when.

It's crazy it's almost like a spark plug non-fouler, this static pre-chamber business. Who knew the thing you put in your old jeep engine to keep it from fouling plugs cause you're too damn lazy to do a valve job on it, is the reason these F1 engines can crank out 800hp from a standard 135lph fuel pump. I feel like the paper does a good job explaining why.

One thing no one has been able to solve with unleaded fuel is knocking that is produced at near lambda 1. Which should theoretically produce maximum power. Maybe the engines run lean normally, so where a normal road car would run rich .8 .7 to keep things safe, these cars run on the other side to keep things safe 1.4 -1.5 under race conditions. But in qualifying, when they turn things up and can go for full fuel flow, max power will always come near theoretical stoichiometry. The only thing you're limited by is knocking.

[johnny comelately]

They tried different barrels, I though the paper was educational as to the different configurations that have been tried over the years, and who tried what and when.

It's crazy it's almost like a spark plug non-fouler, this static pre-chamber business. Who knew the thing you put in your old jeep engine to keep it from fouling plugs cause you're too damn lazy to do a valve job on it, is the reason these F1 engines can crank out 800hp from a standard 135lph fuel pump. I feel like the paper does a good job explaining why.

One thing no one has been able to solve with unleaded fuel is knocking that is produced at near lambda 1. Which should theoretically produce maximum power. Maybe the engines run lean normally, so where a normal road car would run rich .8 .7 to keep things safe, these cars run on the other side to keep things safe 1.4 -1.5 under race conditions. But in qualifying, when they turn things up and can go for full fuel flow, max power will always come near theoretical stoichiometry. The only thing you're limited by is knocking.

yes, yes and yes.
the question of theoretical stoichiometry has to consider boundary layer and other unburnts before one can compare applea and apples.
good paper to advance constructive learning about this uncovered subject

[godlameroso]

They tried different barrels, I though the paper was educational as to the different configurations that have been tried over the years, and who tried what and when.

It's crazy it's almost like a spark plug non-fouler, this static pre-chamber business. Who knew the thing you put in your old jeep engine to keep it from fouling plugs cause you're too damn lazy to do a valve job on it, is the reason these F1 engines can crank out 800hp from a standard 135lph fuel pump. I feel like the paper does a good job explaining why.

One thing no one has been able to solve with unleaded fuel is knocking that is produced at near lambda 1. Which should theoretically produce maximum power. Maybe the engines run lean normally, so where a normal road car would run rich .8 .7 to keep things safe, these cars run on the other side to keep things safe 1.4 -1.5 under race conditions. But in qualifying, when they turn things up and can go for full fuel flow, max power will always come near theoretical stoichiometry. The only thing you're limited by is knocking.

yes, yes and yes.
the question of theoretical stoichiometry has to consider boundary layer and other unburnts before one can compare applea and apples.
good paper to advance constructive learning about this uncovered subject

That's the secret sauce, what about holding radicals under natural EGR to mix with your new incoming mixture? That would take some chemistry on the fuel end.

[johnny comelately]

They tried different barrels, I though the paper was educational as to the different configurations that have been tried over the years, and who tried what and when.

It's crazy it's almost like a spark plug non-fouler, this static pre-chamber business. Who knew the thing you put in your old jeep engine to keep it from fouling plugs cause you're too damn lazy to do a valve job on it, is the reason these F1 engines can crank out 800hp from a standard 135lph fuel pump. I feel like the paper does a good job explaining why.

One thing no one has been able to solve with unleaded fuel is knocking that is produced at near lambda 1. Which should theoretically produce maximum power. Maybe the engines run lean normally, so where a normal road car would run rich .8 .7 to keep things safe, these cars run on the other side to keep things safe 1.4 -1.5 under race conditions. But in qualifying, when they turn things up and can go for full fuel flow, max power will always come near theoretical stoichiometry. The only thing you're limited by is knocking.

yes, yes and yes.
the question of theoretical stoichiometry has to consider boundary layer and other unburnts before one can compare applea and apples.
good paper to advance constructive learning about this uncovered subject

That's the secret sauce, what about holding radicals under natural EGR to mix with your new incoming mixture? That would take some chemistry on the fuel end.

from what i understand it is the free radicals that contribute to detonation and EGR (imo) is the biggest band aid ever known

[godlameroso]

yes, yes and yes.
the question of theoretical stoichiometry has to consider boundary layer and other unburnts before one can compare applea and apples.
good paper to advance constructive learning about this uncovered subject

That's the secret sauce, what about holding radicals under natural EGR to mix with your new incoming mixture? That would take some chemistry on the fuel end.

from what i understand it is the free radicals that contribute to detonation and EGR (imo) is the biggest band aid ever known

There are different types of free radicals, some fast some slow, some create endothermic reactions, other exothermic. Some take a lot of energy some take little energy. Granted most of them are OH or O2 or HHO, but there's other stuff in fuels like branched alkenes, straight chained alkenes, all types of cyclical bonds. The chemistry is incredibly complex, much more complex than the thermodynamic stuff. That stuff has been done to death, but the radical formation, and the reaction rates and all that kinetics stuff, that's where the gains are. Having good understanding of the fuel through it's reactant stages takes a lot of research, but that information is critical to designing the combustion process.

[johnny comelately]

That's the secret sauce, what about holding radicals under natural EGR to mix with your new incoming mixture? That would take some chemistry on the fuel end.

from what i understand it is the free radicals that contribute to detonation and EGR (imo) is the biggest band aid ever known

There are different types of free radicals, some fast some slow, some create endothermic reactions, other exothermic. Some take a lot of energy some take little energy. Granted most of them are OH or O2 or HHO, but there's other stuff in fuels like branched alkenes, straight chained alkenes, all types of cyclical bonds. The chemistry is incredibly complex, much more complex than the thermodynamic stuff. That stuff has been done to death, but the radical formation, and the reaction rates and all that kinetics stuff, that's where the gains are. Having good understanding of the fuel through it's reactant stages takes a lot of research, but that information is critical to designing the combustion process.

OK, I must revisit some papers I have about that, and couldnt agree more that understanding combustion is paramount. one area is determining speed of (whatever) combustion, heat release, expansion and explosion, all in relation to the best push on the rod. and thats another story.
But with our limited resources, I concentrate on design to reduce spots where quick combustion cannot occur, contain the heat for the right amount of time and fit two flame igniters and let her rip. basic I know , but it does work and in the meantime continue learning, for which I thank everyone.

[NL_Fer]

Aren’t you forgetting the mgu-h? The more (excess) air in the mixture, the more the mgu-h can extract from it. Also the turbo has been designed around a certain amount of air/exhaust gas coming through, i don’t believe this still works at lamba 1.0 of it is designed for higher values.

[godlameroso]

The MGU-H extracts heat energy, as you combust air and fuel the volume expands and does work. Less heat means less volume expansion, lower pressure difference between inducer and exducer, and less power for the turbine.

The MGU-H only motors in short bursts under normal operation, the exhaust gases still do the majority of the work. Even with wastegates wide open the MGU-H doesn't have to output 120kw continuously.

[godlameroso]

[Tommy Cookers]

[quote=godlameroso]
The MGU-H extracts heat energy, as you combust air and fuel the volume expands and does work. Less heat means less volume expansion, lower pressure difference between inducer and exducer, and less power for the turbine.[/quote]

you don't properly know what heat is - (neither do I but it doesn't matter)

heat energy in a gas involves both temperature and pressure (and mass)
using more air with the given fuel burn can't reduce total heat energy of the gas before expansion (it didn't go anywhere)
and because the temperature is lower before expansion the amount of heat removed by coolant is less - the whole point

so the amount of energy in the gas for expansive work in the cylinder is greater (and I guess this can be called heat)
after expansion the total heat energy is surely the same (as if without the 'more' air) - but spread over a greater mass of air

I'm not convinced the greater mass of gas at the same temperature (as without 'more' air) yields less work to the turbine
greater mass means more pressure for the same volume or more volume for the same pressure
the turbine draws energy from .....
blowdown (pressure drop x volume) independent of temperature and .....
conversion of heat to work
(remember both in a greater mass of gas starting at the same temperature as if without 'more' air)


or something like that

[johnny comelately]

Aren’t you forgetting the mgu-h? The more (excess) air in the mixture, the more the mgu-h can extract from it. Also the turbo has been designed around a certain amount of air/exhaust gas coming through, i don’t believe this still works at lamba 1.0 of it is designed for higher values.

Not forgetting it, but from my view not all that related except it gets a significant benefit from better combustion.
This comes from:
1. a more complete and quicker combustion for a higher total amount of heat and
2. higher pressure exiting the exhaust valve/port

[johnny comelately]

As an indication of the effect of these, we fitted them(2 per cyl vertically) to a nitro hemi engine running normal 60BTDC timing.
at start up the blower belt went from smooth running to snaking showing that it was almost running backwards.
timing can come back to under 10 degrees, talk about pumping losses, what this saves in lost power is amazing.

[godlameroso]

The MGU-H extracts heat energy, as you combust air and fuel the volume expands and does work. Less heat means less volume expansion, lower pressure difference between inducer and exducer, and less power for the turbine.

you don't properly know what heat is - (neither do I but it doesn't matter)

heat energy in a gas involves both temperature and pressure (and mass)
using more air with the given fuel burn can't reduce total heat energy of the gas before expansion (it didn't go anywhere)
and because the temperature is lower before expansion the amount of heat removed by coolant is less - the whole point

so the amount of energy in the gas for expansive work in the cylinder is greater (and I guess this can be called heat)
after expansion the total heat energy is surely the same (as if without the 'more' air) - but spread over a greater mass of air

I'm not convinced the greater mass of gas at the same temperature (as without 'more' air) yields less work to the turbine
greater mass means more pressure for the same volume or more volume for the same pressure
the turbine draws energy from .....
blowdown (pressure drop x volume) independent of temperature and .....
conversion of heat to work
(remember both in a greater mass of gas starting at the same temperature as if without 'more' air)


or something like that

See my friend now you've opened a can of worms, you can't claim someone doesn't understand things properly when one's own understanding is lacking, we will never learn, we will just argue, and that's not healthy. Much more productive is to meet in the middle somewhere with new synthesized knowledge from both parties. I don't mind being wrong, the total energy from expansion is determined by a few factors, first the mass of air, and second the temperature delta of said mass. Are we on the same path so far? At which point does one have a negative crossover? In other words the greater the mass, the more energy is needed to achieve a given temperature change, friction, pumping losses, etc are just symptoms of this. The fuel imparts x amount of heat to this mass, the volume of said mass increases and does the work we hold so dear.

Now fuel can only release x amount of heat, and as you add more and more air, the heat change of the air mass decreases because the combustion event happens on a finite time scale. The greater air mass has greater resistance to temperature change, at a certain point the density and mass increase from additional boost to the turbine doesn't make up for the lack of volume expansion from reduced temperature change. There is a happy compromise one must find.

The greater the mass the greater the physical push for a given heat release, to a point, but the temperature increase decreases with greater mass for that given heat release. Is this correct?