gruntguru wrote: ↑
Tue Apr 26, 2022 11:40 pm
The more I look at that video the more it appears the spontaneous combustion at the perimeter of the chamber is NOT initiated by events in the pre-chamber. Conclusion - for al least the one cycle shown, combustion would have proceeded without the spark.
The combustion at the perimeter progresses inwards as a flame front - ie not HCCI!
The jet ignition is still responsible for rapidly accelerating the combustion of the remaining charge.
Hypothesis. The spontaneous combustion is a kind of "pre-ignition" event that is accelerated by its proximity to the squish zone and the high turbulence there prevents conversion to a detonation event.
This particular discussion now becomes a matter of timing: which occurs first.
If spon com happened too early it would increase pumping losses unacceptably.
But if, by the appropriate controls, the spark happens just before the critical pressure rise they would complement each other nicely, as the pressure rise after the jet flame aids in the spon com and provides that complete combustion (from all 4 corners of the globe, so to speak).
This would be feasible with knock sensors and cylinder pressure sensors if you can get ahead of the curve (from research) rather than reaction when its all too late to prevent grenading.