Modification of Combustor Stoichiometry Distribution for Reduced NO_x Emission From Aircraft Engines

Measurements of the emissions from an experimental engine were analyzed to construct a design chart for the reduction of oxides of nitrogen (NO_x) in conventional combustors. The design chart was used to reconfigure the stoichiometry distribution of the combustor of a production engine so as to reduce NO_x while holding the emissions of carbon monoxide, unburned hydrocarbons, and smoke well below existing regulations. Combustion section pressure loss and combustor outlet temperature distributions were substantially unchanged. The modified design was refined with the aid of computational fluid dynamics calculations to optimize the emissions reduction. Worthwhile reductions in NO_x were obtained with combustor modifications that are transparent to the engine user.