COMBUSTION MODELS FOR BURNING MULTICOMPONENT PYROTECHNIC NITRATE-METALLIZED MIXTURES

The combustion mechanism of compacted mixtures of metallized fuel powders (Mg, Al, etc.), nitrate-containing oxidizers (NaNO3, KNO3, etc.), organic additives (paraffin, stearin, etc.) and inorganic substances (metal fluorides, metal oxides, etc.) was established under conditions of external thermal influences, according to which the process of transformation of the initial mixture into combustion products is, on average, stationary and proceeds in three spatially separated zones: condensed phase, where decomposition and high-temperature oxidation of components take place; the interface of phases (burning surface), on which the complete decomposition of components and the ignition of metal particles, which then pass into the flame zone, take place; gas phase (zone of heat release in the flame), in which metal particles burn in a diffusion mode, forming combustion products. Models of combustion of mixtures have been developed that take into account the kinetic characteristics of the thermal decomposition of the oxidizer, additives of organic and inorganic substances and high-temperature oxidation, ignition and combustion of metal particles in the decomposition products, as well as the results of thermodynamic calculations of the temperature of the combustion products of the mixtures and the content of high-temperature condensate (non-oxidized metal) in them, which allows with a relative error of 8...10 % to determine the critical ranges of change in the burning rate of mixtures under conditions of external thermal effects, exceeding which can lead both to the acceleration of the burning process of mixtures and fire-explosive destruction of pyrotechnic products, and to a sharp attenuation of their burning process and failure of products.