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 (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≥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.