Influence of surface dielectric barrier discharge on diffusion flame combustion characteristics

The plasma excited by Surface Dielectric Barrier Discharge (SDBD) owns both significant aerodynamic effect and chemical activation effect. In order to analyze the combustion-assisted effect of surface dielectric barrier discharge on shear-coaxial air/methane diffusion flame, the reverse excitation of plasma induced jet is applied to the flame through the use of high-frequency AC power supply in the experiment, and the influence of plasma on the flame combustion characteristics under different combustion conditions is investigated according to the obtained jet flow field schlieren photograph, flame image and CH* spontaneous emission. The results show that the air/methane mixing of elongated shear layer in the upstream of flame is enhanced under the plasma aerodynamic excitation, which enlarges the combustion width of the shear layer. And the combustion heat release rate is also significantly increased, which is mainly related to the plasma activation effect, and the activation effect significantly enhances the combustion intensity of base flame at nozzle outlet. Both the turbulence intensity and jet angle of the flame downstream can be effectively increased with plasma aerodynamic excitation at a reasonably low air flow rate, making the flame height reduced and the flame width enlarged, and the effect tends to be more obvious with a higher discharge voltage. © 2021, Editorial Board of JBUAA. All right reserved.