Dynamics of thermal explosion in the postinduction period

The dynamics of thermal self-acceleration of the reaction and heating is studied for gasless condensed compositions in the induction and postinduction periods up to complete transformation of the substance. It is shown that the propagation of the reaction over the sample is of a distinct frontal character in a broad range of values of the Biot criterion Bi and within the framework of the macrokinetics of “weak” deceleration. Two qualitatively different mechanisms of front propagation are revealed. This is the normal propagation of the combustion front initiated by the ignition zone for large values of Bi. For small values of Bi, propagation of the front is the apparent effect, which is due to subsequent adiabatic self-ignition of separate portions of the substance uniformly heated during the induction period. In the second case, by the propagation velocity, we mean the “phase” velocity.