Combustion of a single carbon or char particle in the presence of high-intensity acoustic fields

The two-dimensional, unsteady, laminar conservation equations for mass, momentum, energy, and species transport in the gas phase are solved numerically in spherical coordinates in order to study the effects of high-intensity acoustic fields on heat and mass transfer, and combustion around a single spherical particle. The particle mass, momentum, and energy equations are solved simultaneously with the gas-phase equations. Since the particle is entrained in an oscillating flow during combustion, the effects of particle entrainment are also investigated. The numerical solution for the case of single particle combustion gives the particle temperature and diameter variation as well as the gas-phase velocity, temperature, and species concentrations as a function of time. The results show that the combustion time decreases with increasing acoustic Reynolds numbers (increasing sound pressure levels) compared with that in a quiescent environment. The combustion time with and without particle entrainment is almost the same at 1000 Hz, but the particle combustion with particle entrainment at 50 Hz takes slightly longer (∼ 3.9% for 100-μm particles) than without entrainment.