Modeling acoustic propagation in a compartment fire

Abstract

Firefighters unable to move and in need of rescue use an audible alarm to signal for help. Rescue teams can then follow this sound to the firefighter. This alarm is governed by NFPA 1982 : Standard on Personal Alert Safety System (PASS). Introduced in 1983, the PASS has saved many firefighter lives. However, a number of incidents have occurred where the PASS is less effective. There have been incidents where the PASS was heard sporadically on the fireground, or where localization of the alarm was difficult, leading to injury and loss of life. We hypothesized that the temperature field created by the fire is distorting the sound, making it difficult to recognize and localize. At ICA 2013, the authors presented experimental results showing changes in the room acoustic transfer function as the fire evolved. This paper will present efforts at modeling these effects. Using a combination of computational fluid dynamics and wave models, a comprehensive model will be presented capable of modeling sound propagation in the firefighting environment. The goal of this work is to develop a PASS signal more robust against distortion by the fire, and better able to serve the firefighting community. [Work supported by DHS/FEMA.]