Numerical simulation of flame propagation in constant volume chambers

Abstract

Combustion of premixed gases inside a closed chamber is computed using a thin flame model at high Damkohler number. The burning velocity is taken as a function of the thermodynamics of the reacting mixture and the flame front curvature. Gas motion due to expansion across the flame is computed assuming an inviscid flow at low Mach number. Results show that the flame is unstable, developing wrinkles which grow into deep indentation along the front. A stabilizing mechanism associated with curvature damps small scales and moderates the rate of growth of perturbation. However, long wavelength perturbations survive and affect the later stages of burning Numerical results are compared with experimental data on flame propagation in a quiescent mixture inside a circular chamber, initiated by central or side ignition sources. Using recent measurement of the Markstein length, good agreement is obtained for the first case. Some deviation is seen in the second case due to heat losse when the flame propagates close to the chamber walls. The model is applied to study the effect of swirl on the rate of burning and pressure rise.