The response of an ethanol pool fire to transverse acoustic waves

Abstract

To investigate the response of a pool fire perturbed by acoustic waves to guide the technology for fire extinguishing by acoustic waves, combustion tests on an ethanol pool fire perturbed by acoustic waves were conducted at acoustic frequencies of 20–100 Hz and acoustic pressures of up to 1.2585 Pa. Firstly, acoustic parameters at the position of the pool flame perturbed by acoustic waves were tested. Secondly, the mass loss rate of the fuel, shape characteristics and oscillation characteristics of the area and height of the pool flames under acoustic perturbance were studied. A modified model of the flame height of the pool fire correlated with mass loss and acoustic parameters was established. The results indicate that, in comparison with situations without acoustic perturbance, the acoustic perturbance suppresses and promotes the dimensionless consumption rate of fuel for the pool fire, while the shape of flames is in stable or disordered state. The dimensionless combustion rate of fuel for the pool fire increases quasi-linearly with the amplitude of sound–induced local periodic displacement. The instability of the pool fire perturbed by acoustic waves is mainly caused by suppressing the dominant frequency and promoting the secondary frequency of flame pulsation.