The Effects of Fluid Motions on Combustion in a Prechamber Bomb

A two-chamber bomb was used to investigate the effect of fluid motions on combustion characteristics, in particular exhaust emissions. Variations in prechamber volume, connecting orifice geometry, air-fuel charge stratification, and initial turbulence of the charge were examined. Tests were run over a wide air-fuel ratio range.

High speed motion pictures were used to study flame propagation and fluid motions. The results show that when the strength of the turbulent jet from the prechamber is varied over a significant range, there is little or no effect on the emissions of oxides of nitrogen (NO_x) over the entire air-fuel ratio range. Hydrocarbon (HC) emissions were found to increase with jet strength in the portion of the lean air-fuel range of most interest (i.e., around 17:1). However, for very lean mixtures the trend was reversed.