Study on unsteady combustion and propelling mechanism of modular charge based on Euler–Lagrange method

This work is focused on the unsteady combustion and propelling mechanism of an energetic propellant bed by establishing a coupling three-dimensional gas–solid two-phase turbulent flow model in cooperation with the combustion model of a high energetic particle swarm and the motion model of the projectile. In addition, the comparison of the breech pressure and the pressure difference between forcing cone and breech from the experiments and simulation are carried out to verify the accuracy of the numerical model. Based on this, the propulsive properties of the propellant bed and the spatial characteristics of pressure waves in the chamber were explored to explain the combustion mechanism of the modular propellant bed and, therefore, ensure the internal ballistic safety of the artillery. Furthermore, associated with the pressure wave effect and the motion behavior of the projectile, the combustion-gas and solid propellant particles exhibit a strong unsteady flow and combustion characteristic. In addition, therefore, the strong unsteady fluctuation of the pressure field in the combustion chamber is further promoted. In fact, this phenomenon is caused by the combined effects on the initial pressure gradient produced by the unsteady combustion of the non-uniformly distributed propellant bed, the end-face stagnation effect of the chamber, the interphase drag effect, before the projectile movement, as well as the competition mechanism between the unsteady combustion of the propellant bed and the projectile movement after the projectile movement.