MIE and flame velocity of partially oxidised aluminium dust

This work presents experimental tools for the determination of Minimum Ignition Energy (MIE) and results concerning the influence of an initial oxidation state on ignition threshold energies and flame velocity. These studies are carried out with micrometric aluminium particles which are oxidised using an anodising process. The first part of this work concerns the description of the experimental devices (Hartmann tube, for MIE measurements, and constant volume combustion chamber for flame velocity measurement with using high speed recording shadowgraphy). In the second part, a review of some results obtained for the sensitivity (MIE) of aluminium particle evolution versus particle diameter, air-fuel equivalence ratio and oxide content is presented. The effect of the oxide content is demonstrated: the MIE increases with the initial oxide content. The sensitivity of oxidised dust remains relatively high for high oxide contents (17.1wt%). The flame velocity is also modified and decreases as the oxide content increases. The most important result seems to be the role of the water content contained in the oxide shell which increases the reactivity of the oxidised aluminium dust.

► We measure the MIE of partially oxidized aluminium dust.
► We measure the flame velocity of partially oxidized aluminium dust.
► We show that water contains in the oxide layer modifies the MIE.
► We show that water contains in the oxide layer modifies the flame velocity.