Structures and burning velocities of flames in iron aerosols

Abstract

The steady flame propagation through a non-volatile fuel suspension is studied. An Eulerian description is used for the gas-phase, while particles are tracked in a Lagrangian framework. The gas-phase model includes both species transport and energy conservation equations. Moreover, expansion of the gas-phase, including particle slip velocity, is taken into account. Gas-phase properties are realistically dependent on temperature and composition. The particle model includes both the transport of oxidizer and surface kinetics. Lastly, a consistent formulation is used for the exchange of mass between the phases. When the particle conversion rate is diffusion-limited, the burning velocity is found to be dependent on local oxygen concentration. Moreover, the effect is sufficiently strong, such that the maximum burning velocity is found at fuel-lean conditions. This demonstrates that both energy and species transport equations in the gas phase and dispersed phase equations must be solved together.