Heat transfer and burning rate studies of B/AP mixture fuels in mini-tubes

As micro-propulsion system is the core component of the micro-spacecraft, ignition and combustion characteristics of propellant fuels directly affect the stabilization and efficiency of the micro-spacecraft. With the help of the infrared camera, the whole process of ignition and combustion of the mixture fuels of amorphous boron and ammonium perchlorate was recorded, and the internal heat transfer process was studied through the observation of mini-tube wall temperature changes. In addition, the moving speed of the burning surface in mini-tubes was calculated by means of the software of GRAFULA, and effect of diameter size, fuel/oxidant ratio and other factors on the burning rate was researched. The results show that for fuels with big reaction enthalpy, the burning rate increases with the decrease of tube diameter; for fuels with small reaction enthalpy, the burning rate decreases with decreasing tube diameter. There exists heat transfer in the axial direction for fuels in mini-tubes, and AP decomposition in the mixture controls the entire reaction process.