A model of burning rate characteristics for heterogeneous propellants over a wide range of pressure

The variation of steady burning rate for heterogeneous propellants over a wide range of pressures is studied by experimental methods and theoretical analysis. Two kinds of heterogeneous propellants, GATo-1 composite modified double-base (CMDB) propellant and 86 series composite propellant are selected. An explanation that two inflection points observed in burning rate-pressure curve is presented. It is concluded that condensed phase reaction dominates the burning process in low pressure region which presents a small pressure exponent, while heat feedback from gas phase predominates in high pressure region with a large pressure exponent. In medium pressure region, these two factors influence the burning process cooperatively and pressure exponent exhibits the trend of reducing and then rising. Results calculated from the model show good agreement with experimental data. Thermal parameters analysis indicates that burning rate is more sensitive to the thermal conductivity of condensed phase, activation energy of condensed phase, specific heat capacity and delay time of heat release of condensed phase reaction in high pressures. Insights and guideline of burning rate characteristics in high pressures and interior ballistic properties for solid propellant impulsive microthruster are provided by our model.