Factors affecting the measurement of the percentage of gaseous products from boron-based fuel-rich propellants

Acid-washed asbestos, carbon fibre, and MgO with carbon fibre were used as the filter media in order to compare their filtering qualities in the estimation of the percentage of gaseous products (PGP) arising from the combustion of singlebase propellants, double-base propellants, and boron-based fuel-rich propellants. The comparison was based on an analysis of the experimentally registered influence of the propellant formulation, the propellant load, the maximum chamber pressure and the thickness of the MgO filter layer on the PGP from the fuel-rich propellant, and in particular on the PGP produced by combustion of boron-based fuel-rich propellant. The results showed that the experimental values of the PGP were closer to the theoretically predicted values when carbon fibre mixed with MgO powder was used as the filter medium. The PGP of boron-based fuel-rich propellant increased when the AP was in part replaced by HMX, when the AP content was increased and when boron was in part replaced by magnesium-aluminum alloy. In terms of the apparatus used in these experiments, the propellant loading density was found to have little correspondence with the PGP for boron-based fuel-rich propellant. The optimal propellant loading density for the chamber volume of 85 cm³ was found to be 2-2.5 g, in view of the reliability and safety of the experiment. It is emphasised that the thickness of the MgO filter layer is very important for the accuracy and reliability of the experiment, and that the optimum should be determined by experiment.