Heat Release in Gas Phase Near Burning Surface of Composite Propellants -Ammonium perchlorate (AP) and Black powder (BP) propellant

To design the rocket motor, thrust and burning rate of propellant are important factors. The large range of burning rate makes the design criteria increase. The range of burning rate is expanded with catalyst or changing the size of oxidizers, however the range of burning rate of ammonium perchlorate composite propellants is small. Black powder has large range of burning rate. The burning rates of propellants are accelerated by conductive heat of reaction zone, therefore it is possible to increase burning rate by evaluating reaction zone. Reaction zone at burning surface of propellant is less than 1mm at 0.1MPa. It is difficult to observe the reaction zone with video camera and to evaluate gas reaction. We measured temperature histories in this reaction zone with small thermo-couple. The temperature fluctuation occurred near burning surface. We also analyzed the temperature vibration. The temperature fluctuation appeared by combustion of solid particles like aluminum or charcoal. Heat of reaction in gas phase is proportional to the partial derivative of the second order with respect to the distance (heat flow) at steady state. The heat flow fluctuated near the burning surface and heat of reaction generated, and the length, l l l l*, from burning surface to fluctuated heat flow, decreased with increasing the burning rate of black powder. The frequency of heat release vibration is 20Hz in the gas phase. The burning rate increases with decreasing the starting time of heat release and period of combustion in gas phase.