gruntguru wrote:
This article confirms what I suggested in the V6 thread:
"I recall at least one paper by Attard et al where the pre-combustion chamber did not contain a supplementary injector - operating instead with the same mixture as the main chamber (stoichiometric in the paper (a Rotax engine IIRC)). The system still offers the benefit of rapid combustion although not the ultra-lean AFR.
Such a system could conceivably operate at say lambda 1.2 - 1.4 in the pre-chamber, with DI stratification producing a much leaner mixture in the regions further from the pre-chamber. So - only one injector per cylinder."
Mixture strength in the pre-chamber would be heavily dependent on spray direction and controlled to some extent by the timing of the injection pulse.
With the spark plug inside the pre-chamber, this must have been a challenge to avoid misfires at very lean operating points. (and would be accentuated if purging of the prechamber does not happen easily, and traps burnt species)
I can get my head around how the TJI as described in the Mark Hughes article would work in homogenous mode. And like you say about the rotax engine with stoichiometric mixture. But for part load conditions or other operating points where the main chamber by itself is lean, it could become a challenge to achieve suitable AFR for ignition to initiate inside the pre-chamber. So in that way, does this architecture of TJI end up limiting how lean you can go?
Agree that its heavily dependent on spray direction. I guess also maybe the shape of the piston too - to direct the vortex from tumble flow to feed the pre-chamber.