表面介质阻挡放电对扩散火焰燃烧特性的影响

针对表面介质阻挡放电（SDBD）在激发等离子体时具有显著的气动效应和化学活化效应，为分析表面介质阻挡放电对空气/甲烷同轴剪切扩散燃烧的助燃效果，实验使用高频交流电源，基于等离子体诱导射流逆向激励对火焰施加控制。根据获取的射流流场纹影图像、火焰图像和CH*自发辐射，研究了等离子体对不同燃烧条件下火焰燃烧特性的影响。结果表明:受等离子体气动激励作用，火焰上游细长剪切层的空气/甲烷掺混得到增强，从而扩大了剪切层燃烧宽度，同时燃烧释热速率会明显提高，这主要与等离子体活化效应有关，并且该效应显著增强了位于喷嘴出口火焰基的燃烧强度。在空气流量较低时，等离子体气动激励可有效增大火焰下游湍流度和射流角，使火焰高度降低、宽度增大，且作用效果随放电电压提高逐渐增强。 

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.