Concentric elliptical jet diffusion flames with co- and cross-flows

► We examine concentric elliptic jet normal and inverse diffusion flames. ► We model turbulent kinetic energy for different velocity ratios and cross-flow. ► Raising the aspect ratio from 1.5 to 3.3 increases the combustion efficiency by 9%. ► Opposing jets increase the turbulent energy to 250% and the stability limits by 45%. ► The cross-flow percent of 70% minimizes HC and NOx emissions to 0.15% and 10 ppm.