Investigation of metallized and nonmetallized hydroxyl terminated polybutadiene/hydrogen peroxide hybrid rockets

Results from 15 static test firings of lab scale hybrid rocket motors using 90% concentrated unstabilized hydrogen peroxide as an oxidizer with hydroxyl terminated polybutadiene fuel are presented. Thirteen of those tests used aluminum or aluminum/magnesium alloy additive in the fuel. The performance characteristics of the propellant combinations were determined. The experimental results indicated combustion efficiencies of 0.72-0.89 and regression rates of 0.5-1.3 mm/s for the metallized fuel combinations. A correlation of the regression rate data for the metallized propellants deviated from that which was derived for turbulent convective heat transfer dominated behavior. A numerical model of the hydrogen peroxide/nonmetallized hydroxyl terminated polybutadiene motor was built using a commercial computational fluid dynamics code. The model was combined with an in-house code to predict the regression rate of the propellant combination, and the flowfield characteristics at the initial operating conditions for two of the experimental tests. The results of the model indicated that the proposed numerical model is a promising tool for mapping the temporal and spatial variation of the regression rate in hybrid motors operating with homogeneous hydrocarbon fuels.