Comparative study on methane/air inverse diffusion combustion performance controlled by surface dielectric barrier discharge plasma

This study investigates the control of methane/air inverse diffusion combustion using surface dielectric barrier discharge (SDBD) plasma technology to enhance methane fuel combustion performance in rocket engines. Under lean combustion conditions (equivalent ratio, Φ = 0.76), forward SDBD dissociates methane C–H bonds via high-energy electrons, generating CH₃ radicals and forming a stable conical flame at 16 kV, while reverse SDBD suppresses turbulence to reduce flame height by 41.7%. At an optimal equivalence ratio (Φ = 1), the reverse structure achieves flame height reduction from 130 mm to 94 mm, whereas the forward structure exacerbates flame nonuniformity due to aerodynamic effects. In rich combustion (Φ \geqslant 1.5), both plasma configurations inhibit methane inverse diffusion combustion, with the forward structure prone to causing flame instability. Analysis confirms that oxygen content is critical to the divergent control effects: forward SDBD excels in high-oxygen environments for combustion enhancement, while reverse SDBD is more effective for flow control in low-oxygen conditions. This research provides experimental insights and technical references for optimizing plasma-assisted combustion in rocket engines.