Practical combustion devices frequently rely upon forced ignition of turbulent fuel/oxidizer mixtures that also contain the product species of combustion. Examples of this include engines that use exhaust gas recirculation (EGR), inter-turbine burners in aircraft engines, and other systems that utilize staged combustion. Although the response of parameters such as auto-ignition delay time and laminar flame speed to dilution with combustion products has been quantified for some fuels, the forced ignition behavior of these mixtures is not well understood. In this work, the effects of major combustion product species (i.e., N2, CO2, H2O, and NO) on forced ignition of CH4/air mixtures were identified and quantified. Additionally, turbulent flame speed measurements of premixed, jet-A/air mixtures were obtained with and without dilution with the same combustion product species. The equivalence ratios, adiabatic flame temperatures, and concentrations of individual diluents in each mixture were systematically changed to highlight the effects of changes in mixture composition, kinetics, and radiation heat loss. Laminar flame calculations were used to provide insight into the changes in chemistry induced by particular diluent species and how these changes impact forced ignition and turbulent flame propagation.
Friday, March 20 at 10:00am to 11:00am
Covell Hall, 117
1691 SW Campus Way, Corvallis, OR 97330