Oparin A. Сombustion of hybrid mixtures

Thesis for the physical and mathematical sciences candidate degree on specialty 01.04.17 - chemical physics, physics of combustion and explosion – I. I. Mechnikov Odessa National University, Ministry of Education and Science of Ukraine, Odessa, 2020. An analytical model for estimating the extreme characteristics of dust explosiveness - maximum pressure and minimum pressure growth rate - depending on the physicochemical characteristics of dust, the particles of which burn in diffusion mode, has been developed. An experimental method of dust generation was proposed, which provides the reaction volume sufficient disaggregation and dusting. Experimental research of aluminum dust explosive characteristics dependence on the concentration and dispersed specifications allowed to conform the experimental data obtained in the conditions of Ukrainian, European and American methods. It was shown that the maximum growth rate critical value has the initial turbulence level due to the pneumatic impulse creation method. Different methods data matching is possible only if this level tends to zero. In experiment this was achieved by varying the ignition delay time. Experimental data processing allowed us to assume that the finely dispersed aluminum particles (ASD-4) burn in combustion wave in the kinetic mode, and coarse - in diffusion mode. Laminar flame in hybrid systems such as polydisperse dust (aluminum) was experimentally studied under isobaric conditions; dust containing solid and gaseous components (aluminum hydride) in fuel; coal dust - methane - air. The normal flame velocity decreases with the particle size distribution function growth, due to a decrease in the specific reaction surface. Critical flash point values for aluminum hydride dust are much lower than those for aluminum, and the flame velocity is much higher. It was shown for the first time that the two-front nature of combustion wave propagation takes place for the aluminum hydride particles air suspension - the primary fast wave is caused by the combustion of hydrogen, formed during hydride decomposition, and the secondary slow wave is caused by the aluminum residue combustion. Comparative experiments on the flame propagation in coal dust - methane - air mixtures, inert component - methane - air and methane – air, have revealed the intensifying role of fine coal in these hybrid mixtures. The results of conducted theoretical and experimental researches allow us to consider aluminum hydride as the most promising high-energy additive to solid rocket fuels.