Characteristics of multiphase detonations and phase transitions in solid-particle fueled continuous rotating detonation ramjet engines

Solid fuels possess great potential for hypersonic flight due to their high energy density and resistance to high-temperature dissociation. However, traditional idealized chemical reaction assumptions fail to accurately describe the complex multiphase detonation and phase transition mechanisms in reactive flows. To address this, a multiphase chemical equilibrium framework is established to systematically investigate the thermodynamic evolution of boron or aluminum fuels within a continuous rotating detonation ramjet engine (CRDRE) physical testbed. Results indicate that the irreversible complete reaction assumption fails completely across Mach 3–7, as it neglects the dissociation effects at high temperatures and pressures. On the other hand, because the gaseous chemical equilibrium assumption fails to capture the condensation phase transitions when products cross their saturated vapor pressures, the assumption is partially invalid for boron at high equivalence ratios, while it exhibits a global failure for aluminum. Consequently, a condition of Mach 7 and 26 km altitude, presenting the most severe dissociation, is selected as the test condition. Using the irreversible complete reaction assumption for boron leads to an overestimation. Conversely, for aluminum, this assumption does not always overestimate engine performance, which is the result of a balance among the combustor heat release, and the heat release/phase transition losses within the nozzle. Furthermore, results indicate that aluminum yields a higher specific thrust compared to boron, whereas boron exhibits a superior specific impulse. This study enables the rapid calculation of solid-particle fueled detonation parameters and solid-particle fueled CRDRE performance, providing reference for multiphase detonation and phase transitions of solid fuels.