Numerical investigation on the engraving process of a pyrotechnic actuator with an improved two-phase flow model of interior ballistic

By combining with an improved model on engraving process, a two-phase flow interior ballistic model has been proposed to accurately predict the flow and energy conversion behaviors of pyrotechnic actuators. Using computational fluid dynamics (CFD), the two-phase flow and piston engraving characteristics of a pyrotechnic actuator are investigated. Initially, the current model was utilized to examine the intricate, multi-dimensional flow, and energy conversion characteristics of the propellant grains and combustion gas within the pyrotechnic actuator chamber. It was discovered that the combustion gas on the wall's constant transition from potential to kinetic energy, along with the combined effect of the propellant motion, are what create the pressure oscillation within the chamber. Additionally, a numerical analysis was conducted to determine the impact of various parameters on the pressure oscillation and piston motion, including pyrotechnic charge, pyrotechnic particle size, and chamber structural dimension. The findings show that decreasing the pyrotechnic charge will lower the terminal velocity, while increasing and decreasing the pyrotechnic particle size will reduce the pressure oscillation in the chamber. The pyrotechnic particle size has minimal bearing on the terminal velocity. The results of this investigation offer a trustworthy forecasting instrument for comprehending and creating pyrotechnic actuator designs.