Dynamics of gas combustion in closed vessels with various laws of flame-surface variation

Model problems regarding the combustion of homogeneous fuel mixtures in closed vessels usually consider the case of a divergent spherical flame. The resultant law of variation of the flame front area is of limited applicability, insofar as the area increases in proportion to the square of the radius. As the law of surface variation is of particular importance to the determination of the basic features of combustion kinetics, it may be chosen in the form of laws realized in the propagation of diverging or converging flames with spherical, cylindrical and plane symmetry. Such flames, more closely related to real processes, aid in studying the influence of flame curvature on combustion rate, and are used in analyses of combustion processes in internal combustion engines, rotating gases and tubes. Various fuel-oxidizer mixtures are examined under the different laws and the results are found to be in good agreement with experimental observations. The spatial velocity of a flame as a function of pressure is the same in all cases, usually decreasing in the course of the process. Under certain conditions there is the possibility of acceleration of the flame as a result of change in the normal velocity of the flame.