Abstract
The instability of hydrogen-air premixed flames propagating in a narrow space is investigated using two-dimensional numerical simulations with the heat loss of Newtonian type. The numerical model contains detailed hydrogen-oxygen combustion with 17 elementary reactions of 8 reactive species and a nitrogen diluent, compressibility, viscosity, heat conduction, and molecular diffusion. A sufficiently small disturbance is superimposed on a planar flame to obtain the linearly most unstable wave number, i.e., the critical wave number. To investigate the characteristics of a cellular flame, a small disturbance with the critical wave number is superimposed. Owing to intrinsic instability, a cellular-flame front is formed. With an increase in the heat loss, the cell depth and burning velocity of a cellular flame becomes smaller, which is due to the decrease in thermal expansion.
