Plasma assisted combustion: effect of a coaxial DBD on a methane diffusion flame

An experimental study of plasma assisted combustion has been initiated at ONERA in order to evaluate the potential application to supersonic combustion with various fuels. For this first step, we choose an easier and more versatile configuration where a coaxial dielectric barrier discharge is applied to a methane diffusion flame. The effects of this discharge on the flame structure and especially the reduction in its detachment height have been investigated. The role of the large scale motion of the flame on its anchoring by the plasma has then been revealed, along with the presence of a plasma channel linking the flame to the burner. Electrical and optical investigations demonstrated the pulsed nature of the light emission of the plasma and the spectroscopic study of OH, CH and N*(2) exhibits a 10mm overlap between the plasma and the flame.