Research on deflagration characteristics and thermodynamic mechanism of micron aluminum powders

Abstract

AbstractTaking three kinds of micron aluminum powder as the research object, taking the deflagration characteristics and dynamic mechanism of aluminum dust as the main line of research, using high‐speed camera system and temperature measurement system to study the dust cloud of three kinds of aluminum powder with different concentration in the transparent pipe dust flame The flame shape, propagation speed, and temperature change law of the propagation device, the flame propagation speed and temperature increase with the increase of dust cloud concentration, and decrease with the increase of particle size; through the experiment of 20 L spherical explosive device, the empirical regression equation of maximum explosion pressure Pmax and maximum pressure rise rate (dP/dt)max is obtained, the explosion pressure (Pmax) will first increase and then decrease with the dust concentration, (dP/dt)max increases with the increase of dust concentration, while Pmax and (dP/dt)max increase with the decrease of particle size; The explosion products of aluminum powder were analyzed by XPS and surface energy spectrum, and the main substances of the explosion products were Al2O3, Al(OH)3, and unburned Al, and the deflagration mechanism model of micron aluminum powder was obtained; at the same time, the simultaneous thermal analyzer (TG‐DSC) was used to conduct microscopic thermal analysis kinetics experimental research on micron aluminum powder with different particle sizes. The combustion process of aluminum powder in the air was divided into three stages. Fit the curve by analyzing and calculate the reaction kinetic parameters of the aluminum dust combustion process. The smaller the particle size of the micron aluminum powder, the more aluminum particles involved in the oxidation reaction, the more intense the combustion reaction, the faster the flame propagation speed, the greater the height of the flame front, the greater the explosion pressure, the exothermic phenomenon is significant, and the activation energy required for the oxidation reaction to occur is smaller.