Flow velocity and temperature distributions in a spherically expanding flame

The flow velocity and temperature distributions during spherical flame propagation in a closed vessel are studied theoretically and numerically. In theoretical analysis, a simplified model that assumes zero flame thickness and a linear reaction rate model that looks into the detailed flame structure are presented. Comparison between results from theoretical analysis and simulation indicates that the temperature of burned gas is over-predicted by the theoretical model since the chemical-equilibrium shift in burned gas is not considered for the compression process. The flow velocity and temperature can be accurately predicted when a modified specific heat ratio is used for the burned gas. It is also found that chemical equilibrium is not immediately reached in the burned gas close to the flame front.