Modeling of Heat and Mass Transfer in Thermoprotective Composite Materials Under Conditions of Phase Transformations at High Temperatures

A comprehensive physical and mathematical model is proposed, as well as a method of analytical solution for the processes of heat and mass transfer in thermoprotective composite materials during phase transformations of composite material binders with the formation of pyrolysis gases and a porous coke residue, through which gases are filtered to the outer boundary and blown into the high-temperature boundary layer. Mathematical simulation is carried out on the basis of the identified law of decomposition of composite material binders without using models of the hard to formalize chemical kinetics and therefore suitable for most thermoprotective composite materials. The comprehensive physical and mathematical modeling includes the formation of a pyrolysis zone, the speeds of its motion inside the composite material, determining the density of composite material and pyrolysis gases in the pyrolysis zone, the density and stagnation pressure of gases in this zone, their nonisothermal filtration through the porous residue with injection into the boundary layer, as well as heat transfer in the presence of nonstationarily moving boundaries of phase transformations. Based on the relations of the proposed model, calculations were carried out, and their results were analyzed.