Temperatures in a turbulent diffusion flame with and without exposure to an electric arc

Both emission and coherent anti-Stokes Raman spectra (CARS) were used to measure spatially-resolved temperature and relative species concentration profiles in a turbulent diffusion flame exposed to an electric arc. Relative appearances of three important intermediate combustion species (CH, C₂, and CN) were inferred from emission-intensity profiles. Electronic, vibrational, and rotational temperatures in the flame with and without the electric arc were deduced from the ro-vibrational spectra of these species. The ground-state temperatures of the major species were obtained by N₂-CARS measurements. Analysis of the experimental results indicated that different thermodynamic temperatures (vibrational and electron, rotational and ground-state) co-existed in an electric-arc-assisted flame. The apparent changes caused by the arc on the reaction kinetics and the thermal structure of the flame are discussed; recommendations are made for better computational modeling of these devices.