DYNAMICS OF ALUMINUM COMBUSTION

A study has been performed modeling both steady and unsteady combustion of aluminum, Law's steady-state aluminum combustion model has been expanded to include the effects of multiple oxidizers and their products, oxide accumulation on the surface of the burning aluminum particle, and convection, Both transport and thermodynamic properties are calculated internally for varying temperatures, relaxing the normal assumption of unity Lewis number, The aluminum combustion model has been compared to experimental data from burners, laser-ignited particles, and propellant under a variety of conditions, showing a reasonable degree of agreement, Calculations with the model show that O-2 is a stronger oxidizer than H2O, which in turn is stronger than CO2. The aluminum combustion model was incorporated into a computer model for predicting acoustic effects in a Rijke burner. Calculations have shown that a significant part of the increase in acoustic growth due to the addition of aluminum is due strictly to the change in the gas temperature profile, The change in temperature profile apparently causes the location of the velocity antinode to shift relative to the Rijke hurner Flame and thereby cause an increase in the flame response. The acoustic model agrees reasonably well with available acoustic growth rates fur data where aluminum particles have been added to a propane Rijke burner.