Nano-Aluminum Aerosol Characterization With Application To Heterogeneous Shock-Tube Combustion

Since typical solid propellant ingredients such as aluminum have the capacity to be produced as nano-particles, there is a need for the combustion characteristics of this common solid fuel and other metals to be revisited. However, quantitative combustion measurements of nanopowders are complicated due to factors such as particle agglomeration, concentration, and size distribution. The results are often controversial and are not always repeatable. In the current study, an aerosol of nano-aluminum powder in air is created using a particle injector and sampled with a scanning mobility particle sizer to determine how the mean particle size and number concentration change with time. For all cases studied, the mean particle diameter grew with increasing time, and the number concentration of particles in the aerosol decreased from the time of injection. Although these trends are to be expected from general aerosol theory, this study shows that typical monoand polydisperse theories of coagulation are not sufficient to predict the exact nature of the suspended particles. From the results of this study, future heterogeneous shock-tube experiments utilizing these nano-aluminum particles will be more quantitative in nature than previous studies, where relatively little was known of the particles contained within the aerosol