Modelling reaction propagation for Al/CuO nanothermite pellet combustion

Abstract

A continuum-scale model for the combustion of consolidated nanothermite pellets is introduced. A simplified chemical kinetics model is used for the solid state nanothermite reaction while a two-phase porous media flow accounts for the mass and heat transfer within the consolidated pellet under an equilibrium thermodynamic assumption. The thermophysical and chemical kinetic properties of the Al/CuO nanothermite pellets are determined from the literature. A sensitivity analysis reveals the relative importance of these modelling parameters for both the advection and conduction-dominated combustion regimes. Based on the governing equations, we propose a thermodynamically consistent non-dimensionalization of the global Peclet and Damköhler numbers which are based on the characteristic Darcy velocity within the porous pellet. The non-dimensionalization results in a linear scaling between the normalized burn rate and Peclet number, which allows a collapse of the numerical results with published experimental data. We identify a transition between the conduction- and advection-dominated combustion based on the transient burn rate of the nanothermite pellet combustion.