Modeling and Simulation of Laser‐Induced Ignition of RDX Using Detailed Chemical Kinetics

Abstract

A laser‐induced ignition model of RDX is developed, in which a detailed chemical kinetics scheme, containing 45 species and 231 reactions, is employed to describe the reaction in the gas phase. The model is spatially one‐dimensional and includes the transient development of two regions: the condensed phase and the gas phase. The condensed phase is composed of solid RDX, liquid RDX, and some decomposition products. The main physicochemical processes include melting, decomposation, vaporization, and radiation absorption. The gas phase is composed of RDX vapor and reaction products and the main processes include convection, diffusion, heat conduction, chemical reaction, and radiation absorption. With interfacial boundary conditions, the governing parameters for the condensed phase are conservation equations of energy and species concentration, whereas those for the gas phase are the conservation equations of mass, momentum, energy, and species concentration. A finite difference program using FORTRAN is compiled and numerical simulation is carried out. The ignition process of RDX is discussed from the distribution and evolution of temperature and species concentration. The model can provide a reasonable prediction of the phenomenon that the flame moves towards the surface immediately after ignition, and then departed from the surface.

Study of the enhanced burning rate during the plasma-propellant interaction process

“…It is expected that the enhanced burning rate coefficient is much larger during the plasma action phase. The capillary plasma temperature is usually 10 000-15 000 K [34] and the flame temperature in the conventional ignition mode is usually 1500 K-3000 K [22]. According to the grey body radiation theory, the radiative heat transfer in the plasma ignition mode is about 625-10 000 times of that in the conventional model.…”

“…It is assumed that the ablation process dominates the PPI process, and the ablation rate is calculated based on the kinetic ablation model [19], which is widely used to model the interaction mechanisms [20,21]. However, the ablation-domination assumption might be reasonable in the pre-ignition PPI stage, but not appropriate for the plasma ignition process, because the chemical reactions including the decomposition of the propellant, the oxidation reaction and catalytic reaction, are essential to determine the temperature, pressure and species in the reaction zone [22]. In addition, due to the complex compositions of plasma, the species transportation is also very important [23].…”