Simulation Study Aids Halon Replacement Effort for Combat Aircraft

Abstract

In cooperation with the Montreal Protocol to eliminate ozone depleting compounds, the Air Force is searching for feasible alternatives to halon fire suppressants. The effort reported here was the first step in developing an overall simulation model to help screen fire suppressant alternatives. A continuous simulation model was developed to predict fuel fire ignition in an aircraft dry bay and fuel tank caused by the detonation of a high explosive incendiary (HEI) projectile. The model, written in the SLAM II simulation language, predicts temperature and pressure conditions in the dry bay and fuel tank continuously by integrating a set of four simultaneous equations. The matrix of equations is based on the ideal gas law and conservation of inass, energy, and species equations. The simulation is unique in that it combines an HEI threat with continuously modeled dry bay and fuel tank environments. This simulation has been validated against available empirical data. Future enhancements are underway to better characterize the HEI fragmentation and blast wave pressures and also to add the fire suppression subroutines needed to evaluate the halon alternatives.