Studies on the stability limit extension of premixed and jet diffusion flames of methane, ethane, and propane using nanosecond repetitive pulsed discharge plasmas

This paper examines the stabilization of premixed and jet diffusion flames of methane, ethane, and propane by nanosecond repetitive pulsed plasma discharges. Combustion products are measured using gas chromatography while laser-induced breakdown spectroscopy (LIBS) is used to characterize the local equivalence ratios. We find that in premixed flames, although plasma-assisted flame holding takes place under fuel-lean conditions, propagation of combustion occurs at/or above the known lean flammability limits. In jet diffusion flames, the flames are found to be anchored best to the discharge at jet speeds that are much higher than the normal blow-off speed when the discharge is placed where the local fuel-air equivalence ratio is in a limited flammable regime.