Analysis of Overpressure in Bore Caused by Fragmentation of High Energy Gun Propellants

At the initial stage of launch, the propellants may break up in advance under the impact of the gas in the chamber, resulting in a sharp increase in the burning surface, which is an important reason for the formation of overpressure in the chamber and the initiation of the chamber explosion. In order to study this problem, the fracture model of high-energy propellants in bore under different shape parameters, material properties and initial temperatures was established. Then several kinds of propellant samples were tested by means of dynamic impact crushing equipment of propellants. And the experimental results were used to compare and correct the theoretical model. The modified model was coupled with the internal ballistic model to obtain the influence law of different degree of fragmentation of propellants on chamber pressure. Based on the above studies, the coupling model can simulate the overpressure in bore caused by the fragmentation of propellants and be used to analyze the conditions for the occurrence of overpressure. The results provide a basis for the design of new charging structure and the bore safety evaluation of ammunition.