Combustion of nano-aluminum and liquid water

Abstract

An experimental investigation on the combustion behavior of nano-aluminum (nAl) and liquid water has been conducted. In particular, linear and mass-burning rates of quasi-homogeneous mixtures of nAl and liquid water as a function of pressure, mixture composition, particle size, and oxide layer thickness were measured. This study is the first reported self-deflagration on nAl and liquid water without the use of any additional gelling agent. Steady-state burning rates were obtained at room temperature (∼25 °C) using a windowed vessel for a pressure range of 0.1–4.2 MPa in an argon atmosphere, particle diameters of 38–130 nm, and overall mixture equivalence ratios ( ϕ) from 0.5 to 1.25. At the highest pressure studied, the linear burning rate was found to be 8.6 ± 0.4 cm/s, corresponding to a mass-burning rate per unit area of 6.1 g/cm 2 s. The pressure exponent at room temperature was 0.47, which was independent of the overall mixture equivalence ratio for all of the cases considered. The mass-burning rate per unit area increased from ∼1.0 to 5.8 g/cm 2 s for an equivalence ratio range of 0.5–1.25. It varied inversely to particle diameter, increasing by 157% when the particle diameter was decreased from 130 to 50 nm at ϕ = 1.0.