Study on Thermophysical Properties and Electrical Conductivity Characteristics of Combustion Products from Propellants with Ionization Seeds

Detailed knowledge regarding the thermophysical properties and electrical conductivity of the combustion products derived from solid propellants is essential for the optimized design and operation of solid-fuel rocket engines employing magnetohydrodynamic drive technology. However, the high-temperature and high-pressure environment prevailing during rocket operation makes the experimental measurement of these characteristics extremely difficult, while the ionization reactions obtained by adding ionization seeds containing cesium to solid propellants for increasing the electrical conductivity of gaseous combustion products makes the theoretical calculation of these characteristics extremely problematic as well. The present work addresses these issues by constructing a minimum Gibbs free energy constraint function in conjunction with the Debye–Hückel correction under the condition of ionization to calculate the equilibrium components of combustion products. The obtained equilibrium components are then applied in conjunction with Lennard–Jones potential energy theory and the Champan–Enskog framework to approximately calculate the specific heat, viscosity coefficient, and thermal conductivity of propellant gases over a wide range of temperatures and pressures. The Kantrowitz model is proposed to solve the electrical conductivity of combustion products. Finally, the accuracy of the numerical calculations is validated through the Langmuir probe experiment. The discrepancy between calculated and measured electron density decreases with increasing temperature and remains within 5% when the combustion product temperature exceeds approximately 1800 K. The validity of the proposed framework is demonstrated by examining the effects of temperature, pressure, and ionization seed content on the thermophysical properties and electrical conductivity of the combustion products derived from tri-base solid propellant with cesium atoms employed as ionization seeds.