Diffusion Flame Calculations for Composite Propellants Using a Vorticity-Velocity Formulation

摘要

A two-dimensional model has been developed to study the flame structure above composite propellants using a vorticity-velocity formulation of the transport equations. This formulation allows for a more stable, robust, accurate, and faster solution method compared with the compressible Navier-Stokes equations in the low Mach flow regime. The model includes mass and energy coupling between the condensed and gas phases. The condensed-phase model is based on previously reported one-dimensional models and includes distributed decomposition and multistep-reaction kinetics. The model uses a detailed gas-phase kinetic mechanism consisting of 37 species and 127 reactions. The kinetic mechanism and species diffusion determine the flame structure of the system; no assumptions are made beforehand, aside from appropriate boundary conditions. Numerical studies have been performed to examine the flame structure above an ammonium-perchlorate/hydroxy-terminated-polybutadiene propellant. The predicted flame structure was found to be qualitatively similar to the Beckstead-Derr-Price model with both premixed and diffusion flames present. Results present significant insight into ammonium perchlorate's ability to control a propellant's burning rate and illustrate the importance of the primary diffusion flame in composite propellant combustion.