Hot-Spot-Modelling to Simulate the Influence of Particle Properties on Ignition of Solid Propellants

Pyrotechnic ignition of solid propellants is a highly transitional process. Modelling such a process is challenging because the heat transport during the ignition occurs not only by heat conduction and convection but also by radiation and by particles. The jet of an ignitor usually consists of gas and some condensed material (particles, drops) impinging the propellant surface. Here, a few aspects of the influence of the impinging particles on the ignition of solid propellants are simulated and discussed. A large number of parameters influences the ignition of a solid propellant by particles. Beneath the material properties of the propellant, size, number, size distribution, distribution in space, temperature and energy content of the particles are some of the particle properties that have to be considered. A 3D-model is presented that uses hot spots in a reactive homogeneous material to simulate single particles impinging the propellant. As a simplification, heat feedback from the flame is not considered. Calculations result in temperature distributions, which allow the determination of ignition delay time, reaction progress and ignition energy.