Ray tracing and finite element modeling of sound propagation in a compartment fire

TL;DR

This study compares experimental measurements and numerical models of sound propagation in a room with a fire, revealing how fire-induced temperature gradients affect acoustic wave behavior and frequency response.

Contribution

It introduces a combined modeling approach using FDS, COMSOL, and Bellhop to simulate fire-affected acoustics and validates it against experimental data.

Findings

Wave-fronts arrive earlier in fire conditions

High frequency modes are significantly attenuated

Model predictions align well with experimental observations

Abstract

A compartment fire (a fire in a room or building) creates temperature gradients and inhomogeneous time-varying temperature, density, and flow fields. This work compared experimental measurements of the room acoustic impulse/frequency response in a room with a fire to numerically modeled responses. The fire is modeled using Fire Dynamics Simulator (FDS). Acoustic modeling was performed using the temperature field computed by FDS. COMSOL Multiphysics was used for finite element acoustic modeling and Bellhop for ray-trace acoustics modeling. The results show that the fire causes wave-fronts to arrive earlier (due to the higher sound speed) and with more variation in the delay times (due to the sound speed perturbations). The frequency response shows that the modes are shifted up in frequency and high frequency (>2500 Hz) modes are significantly attenuated. Model results are compared with data and show good agreement in observed trends.