Turbulent Jet Ignition is an advanced pre-chamber initiated
combustion system for an otherwise standard spark ignition engine
found in current on-road vehicles. This next-generation pre-chamber
design overcomes previous packaging obstacles by simply replacing
the spark plug in a modern four-valve, pent roof spark ignition
engine.
Turbulent Jet Ignition enables very fast burn rates due to the
ignition system producing multiple, distributed ignition sites,
which consume the main charge rapidly and with minimal combustion
variability. The fast burn rates allow for increased levels of
dilution (lean burn and/or EGR) when compared to conventional spark
ignition combustion, with dilution levels being comparable to other
low temperature combustion technologies (homogeneous charge
compression ignition - HCCI) without the complex control
drawbacks.
This paper focuses on preliminary performance, efficiency,
emissions and combustion effects of a Turbulent Jet Ignition system
operated with commercially available fuels at the worldwide mapping
point of 1500 rev/min, 3.3 bar IMEPn (~2.62 bar BMEP).
Single-cylinder experimental results highlight that the pre-chamber
combustion system is capable of tolerating up to 54% mass fraction
diluent while still maintaining adequate combustion stability. The
high diluent fraction has enabled the pre-chamber combustion system
to record an 18% improvement in fuel consumption when compared to
conventional stoichiometric spark ignition. The efficiency
improvements are due to a combination of combustion improvements,
the near elimination of dissociation due to the low combustion
temperatures and reduced engine throttling. Additionally, the low
temperature combustion has resulted in single-digit ppm engine-out
NOx emissions with controllable levels of HC and CO emissions.
