Study of Combustion Characteristics of Magnesium/Sodium Nitrate Pyrotechnics Under Sub-Atmospheric Pressure.

In order to study the combustion characteristics and reaction mechanism of luminescent pyrotechnics under sub-atmospheric pressure conditions, low-pressure combustion tests and thermal analysis were performed for magnesium/sodium nitrate pyrotechnics with zero oxygen equilibrium in the pressure range of 1 kPa~101 kPa. The results reveal that when the pressure drops, the flame height rises, and the flame transitions from a steady-state convergent to a turbulent evanescent flame. Reduced oxygen concentration at low pressure reduces the flame's high temperature response zone, as well as burning speed and luminous intensity. Furthermore, both the light intensity and the burning rate comply with Vier's law. The weight loss increased from 16.3% to 36.7% when the pressure was reduced from atmospheric pressure to 1 kPa, the enthalpy change of reaction decreased from 6.75 kJ/g to 2.45 kJ/g, and the characteristic peak of magnesium oxide at 500 nm in the flame spectrum disappeared at 1 kPa, indicating that the reduction of pressure would affect the degree of reaction of pyrotechnics, leading to the decrease of magnesium oxide content and the decrease of heat release. These scientific findings provide useful insights into the low-pressure combustion behavior of pyrotechnics and support the growing demands for military and civilian applications. [ABSTRACT FROM AUTHOR]