Surface temperature of agglomerated aluminum particles in a reaction zone

摘要

Aluminum particles are used as a metal fuel to increase the propulsion performance of composite propellants in solid rockets. As such, the combustion mechanism of aluminum has received considerable research attention. Aluminum gas reacts with surrounding oxidizers and creates the diffusion flame. The evaporation time is proportional to the square of the particle diameter, with a constant of proportionality that depends on the temperature difference between the luminous flame and the agglomerated aluminum particle surface. The luminous flame temperature is easily obtained theoretically, but the surface temperature is yet to be obtained experimentally. If the surface temperature could be obtained, the difference between the boiling temperature and the surface temperature of aluminum particles would be clarified. Therefore, it is necessary to study the agglomerated aluminum particle surface. In this study, the dependence of aluminum particle surface on the atmospheric pressure and on the particle diameter is investigated. It is established that the surface temperature is lower than the boiling temperature of aluminum. The mean surface temperature is a constant with respect to the particle diameter from 100 to 500 μm at 0.1 MPa. Also, it is clarified that the surface temperature is determined by energy balance at aluminum particle surface.