Edward D. Klomp

Calculated nitric oxide emissions of an unthrottled spark ignited, stratified charge internal combustion engine

This paper presents a theoretical study of nitric oxide emissions from an unthrottled stratified charge, spark ignition engine. A three-region (generally rich, stoichiometric, and lean) combustion model was used, and the effects of the following variables were studied: 1. Excess air number of the rich mixture. 2. Percentage of the total fuel in the rich-mixture region. 3. Percentage of fuel burned stoichometrically. 4. Exhaust gas recirculation, percentage and distribution. Comparisons are made to both experimental results from a throttled engine and calculated results for an unthrottled engine with a homogeneous mixture. For illustrative purposes, an application of the model to a particular geometrical form of charge distribution is analyzed.

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. 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 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. /GMRL/