A Novel Combustion Platform for Microwave Plasma-Assisted Combustion Studies

A novel plasma-assisted combustion (PAC) platform is developed and characterized with the ability to decouple the underlying mechanisms and aid in the study of PAC. This unique platform allows for the initial separation and controlled coupling of the plasma, the fuel, and the oxidizer streams in different combinations, which is useful in investigating the various reaction pathways in PAC. Three operation schemes (I-III) were investigated to showcase the platform's capabilities. In Scheme I, the argon plasma was coupled to a premixed mixture of the fuel and oxidant. While in Schemes II and III, the argon microwave plasma was coupled to either the oxidizer stream or the fuel stream, with the resulting mixture subsequently joining the fuel and oxidizer streams, respectively. Images obtained for various fuel equivalence ratios in each operation scheme showed distinct differences in the flame structures despite keeping all experimental parameters' constant. The emission spectra obtained at different spatial locations in the combustion platform also depicted distinct emission features for each operation scheme. It is thus inferred that the mechanism through which the plasma assists the combustion in each of these operation schemes is different, highlighting the capability of the novel PAC platform in unraveling the various pathways through which the combustion enhancement is achieved. Hence, the results obtained demonstrate the versatility of the novel PAC platform in discriminating between the various reaction pathways in the PAC of the lean fuel/air mixture.