Thermal Theory of Burning Rate

A schematic representation of the combustion wave structure of a typical energetic material is shown in Fig. 3-9, and the heat transfer process is shown in Fig. 3-10 as a function of the burning distance and temperature. In zone I (solid phase zone or condensed phase zone), no chemical reactions occur and temperature increases from the initial temperature (T0) to the decomposition temperature (T ). In zone II (condensed phase reaction zone), temperature increases from Tu to the burning surface temperature (Ts), where phase change from solid to liquid and/or to gas occurs 

The basic assumptions in the following description of the burning rate model are 

Radiative energy from the gas phase is absorbed at the burning surface. 

With reference to Figs. 3-9 and 3-10, the energy and the species equations are  

Several additional assumptions are applied to the above equations19,101 (1) no endothermic or exothermic reaction is involved within the condensed phase (below the burning surface), (2) the luminous flame zone does not contribute to the conductive heat feedback from the gas phase to the burning surface, and (3) no species diffusion occurs in the condensed phase or in the gas phase. Equations (3.39) and (3.40) are then simplified as follows  

---