Optimization of global kinetics parameters for heterogeneous propellant combustion using a genetic algorithm

Abstract

We examine the combustion of heterogeneous propellants for which, necessarily, the chemical kinetics is modelled using simple global schemes. Choosing the parameters for such schemes is a significant challenge, one that, in the past, has usually been met using hand-fitting of experimental data (target data) for global burning properties such as steady burning rates, burn-rate temperature sensitivity, and the like. This is an unsatisfactory strategy in many ways. It is not optimal; and if the target set is large and includes such things as stability criteria, or bounds, difficult to implement. Here we discuss the use of a general optimization strategy which can handle large data sets of a general nature. The key numerical tool is a genetic algorithm that uses MPI on a parallel platform. We use this strategy to determine parameters for HMX/HTPB propellants and AP/HTPB propellants. Only one-dimensional target data are used, corresponding to the burning of pure HMX (AP) or a homogenized blend of fine HMX (AP) and HTPB. The goal is to generate kinetics models that can be used in the numerical simulation of three-dimensional heterogeneous propellant combustion. The results of such simulations will be reported in a sequel.

Keywords:

• AP/HTPB
• Combustion
• Global-kinetics
• HMX/HTPB
• Optimization
• Propellants

Acknowledgments

This work was supported by the AFRL, the Air Force Office of Scientific Research and by the US Department of Energy through the University of California under subcontract B341494. We are grateful to R.Yetter for valuable discussions of chemical kinetics.