Burning Rates of Nanoaluminum–Water Solid Propellants at Various Pressures

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Burning Rates of Nanoaluminum–Water Solid Propellants at Various Pressures

Wollmark, Shahar / Yavor, Yinon

The burning rates of solid propellants comprising different nanoaluminum powders and distilled water were examined at pressurized conditions up to $P = 7.5 MPa$ . Several aluminum powders were tested using a strand burner technique: uncoated nanopowder (ALEX), stearic-acid coated nanopowder (L-ALEX), Viton-coated nanopowder (V-ALEX) with two different particle sizes, and bimodal mixture of V-ALEX and micrometer-size powders. Propellants containing ALEX, L-ALEX, and bimodal compositions followed the power law relation throughout the pressure range, with pressure exponents of $n = 0.34$ , 0.5, and 0.28, respectively. Propellants containing V-ALEX powder demonstrated two different regimes: at pressures lower than 1.8 MPa, the burning rates were constant with respect to pressure; whereas for higher pressures, the burning rates followed the power law relation with $n = 0.68$ and $n = 0.81$ for powder diameters of 60 and 100 nm, respectively. The combustion efficiency, defined as the fraction of aluminum that oxidized during combustion, showed high values (90–95%) for all tested compositions.