The desired product composition and thermodynamic properties produced by a closed combustion chamber is heavily influenced by reactant distribution and ignition source. A fundamental and defining mechanism behind these reaction properties is the burn rate which is a strong function of local equivalence ratio gradient and vaporous fuel concentration when ignition conditions are reached. The ignition source location and the ensuing combustion process rely on the vaporous fuel concentration at local volumes of high energy gradient within the combustion chamber.

Desirable operation characteristics for internal combustion engines, such as low temperature of combustion to achieve low NO production are often reached at lean local and/or lean global equivalence ratios. As a result, advanced fuel injection systems and combustion chamber design attempt to maintain a stable reaction at the edge of the lean blowout limit. The study performed here presents a comprehensive analysis of the effect of equivalence ratio gradient and concentration properties to enable a stable lean burn to improve engine efficiency and lower pollutant emissions.

The parametric study utilizes the KIVA3 code to investigate the effect of nozzle geometry, fuel injection timing and duration to control the local equivalence ratios to maximize engine efficiency while minimizing nitrogen oxide pollutant emissions. It concludes that through varying fuel injection start and duration and currently available cost effective technologies to produce nozzles with an increase in number of fuel injection holes, emissions can be reduced while still preserving or increasing power and efficiency