Influence of compressibility on propagation of curved flames

The nonlinear problem of propagation of a curved stationary flame in a compressible flow is studied by means of two-dimensional numerical simulations of the complete set of equations of flame dynamics including chemical kinetics, thermal conduction, and fuel diffusion. It is shown that curved shape of a flame in a compressible fuel mixture leads to stronger increase of the flame velocity than in the case of isobaric flames. It is found that acceleration of a flame due to the development of the curved shape generates a shock of noticeable intensity ahead of the flame front. The shock compresses the fresh fuel and, in turn, changes parameters of the flame. As a result, strongly curved flames in compressible flows can be observed in tubes much narrower than in the case of isobaric flows. Additional amplification of the flame velocity is obtained due to the development of asymmetrical structures at the flame fronts in wide tubes.