Research on the effects of diluents and dilution ratios on laminar burning velocities and flame instabilities of hydrogen flame

Laminar burning velocities and flame instabilities of H2/O2/diluents mixture were studied at initial pressure of 0.3 MPa, initial temperature of 373 K and equivalence ratio of 1.0. The He diluted mixtures have the largest laminar burning velocities and the N2 diluted mixtures have the smallest, while He diluted mixtures have the largest mole fraction of H and OH radical and N2 diluted mixtures have the smallest. And laminar burning velocities fall when the dilution ratio rises, due to the mole fractions of H and OH radical fall with increasing dilution ratio. The cellular structure appeared on both N2 and Ar diluted mixture, while only wrinkles grew on He diluted mixtures. When dilution ratio rose, the appearance of cellular structure deferred. Thus, He diluted mixtures are more stable than N2 and Ar diluted mixtures, and higher dilution ratios restrain the flame instabilities.