Expermiental study of a methane diffusion flame under dielectric barrier discharge assistance

Summary form only given. Plasma assistance is a promising way for combustion improvement, especially for NO_x reduction by burning leaner premixed hydrocarbons or for flame stabilization under unfavorable conditions (supersonic combustion or, small volume combustion where the chemical time is close to the fuel residence time). Thus, we conceived a combustion test bench where we could study the effect of a coaxial dielectric barrier discharge on a lifted non-premixed methane flame. For this study, we are especially interested in the effect of the discharge on the detachment height of the flame up to blow-out. There, we could achieve the anchoring of the flame (detachment height = 5-10 mm against 50-60 mm without plasma) on a plasma channel going out from the burner exit. Electrical investigations demonstrated that only 1 W applied to the discharge at the nozzle of the burner was necessary to this anchoring. Coupling electrical and optical measurements revealed the pulsed nature of the light emission of the plasma while spectroscopic study of OH, CH and N₂* exhibits a 10 mm overlap between the plasma and the flame. Finally, fast camera movie of the flame anchoring zone was also achieved using narrow band filters for the selection of OH, CH and N₂