Effect of Inert Gas on Turbulent Burning Velocities

In our previous works, the preferential diffusion effect was found to play an important role in premixed turbulent combustion characteristics, where nitrogen was added as an inert gas to several fuel/oxygen mixtures. In this study, the inert gas is changed to Ar, He and CO₂, and the relationship between the turbulent burning velocity and the diffusion coefficient of each inert gas in the multi-component mixture is examined experimentally. As a result, Ar and CO₂ added mixtures show slightly larger turbulent burning velocities than that of nitrogen added mixtures. On the contrary, He added mixtures show very smaller turbulent burning velocities at the same equivalence ratio. These characteristics are discussed in connection with each diffusion coefficient of fuel, oxygen and inert gas in multi-component system.