? 2022 The Combustion InstituteA newly reported oxidizer, hydrogen peroxide encapsulated in silica xerogel (hydrogen peroxide gel), is prepared and applied to the combustion of aluminum particles in this study. Linear and mass burning rates of the highly viscous mixture of hydrogen peroxide gel and micron-aluminum (μAl) were measured as a function of mixture composition, pressure, and particle size. Steady-state burning rates were obtained at room temperature using an optical vessel for a pressure range of 3.6–12.0 MPa in argon, an oxidizer-to-fuel weight ratio (O/F) from 0.8 to 2.0, and particle diameters between 1 and 12 μm. The homogeneous mixture of hydrogen peroxide gel and μAl was able to be ignited over a wide O/F range of 0.8–2.0, even at low pressures (e.g., 3.6 MPa). At a nominal pressure of 3.6 MPa, mass burning rates ranged between 4.45 g·cm?2·s?1 (O/F = 0.8) and 1.26 g·cm?2·s?1 (O/F = 2.0), which corresponded to linear burning rates of 35.1 and 8.5 mm·s?1, respectively. In the pressure range of 3.6–10.0 MPa, linear burning rates of the oxidizer-rich mixture (O/F = 1.7) were linearly increased with pressure increasing and the pressure exponent (n) was 1.05. The combustion reaction was kinetically controlled within this pressure range. However, when the pressure beyond ～10 MPa, there was a transition in pressure dependence and the burning rate tended to be constant. In addition, burning rates of the mixture were inversely proportional to Al particle diameter, increasing by 3.06 times when the particle diameter was decreased from 11.02 to 1.84 μm at stoichiometric ratio.
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