MODELING OF HIGH PRESSURE WATER MIST SUPPRESSION SYSTEMS FOR THE PROTECTION OF AIRCRAFT HANGARS

Abstract

The U.S. Congress has mandated the phase out of foam suppression systems for the protection of aircraft hangars due to the toxic composition of fluorine foams. Water mist is one alternative proposed to replace foam systems. This study examines high pressure water mist systems in a ceiling configuration and a floor and ceiling combination layout on three fire scenarios in FDS. This work is split into three models- the fire model, the water mist model, and the extinction and evaporation model before combining each component in a final hangar configuration. Within the fuel model, three radiation modeling options were tested, and each fire was constructed. The water mist model tested the length scales of the jet stream and associated grid resolution. The evaporation model was verified to ensure accurate heat transfer between Lagrangian particles and the gas phase. Simulations in the final hangar configuration showed the high-pressure water mist systems were able to provide fire control, performing better at an earlier activation time. The floor and ceiling combination layout provided faster control compared to the ceiling nozzle only layout. A wind condition was added in a second round of testing, but minimally impacted the performance of the systems.