Static Equilibrium Characteristics of Full-Flow Staged Combustion Cycle Engine Under Different Propellants

Abstract

The full-flow staged combustion cycle (FFSC) engine is a promising liquid rocket propulsion system owing to its capacity for high specific impulse. The present study introduces an equilibrium model of the FFSC engine, utilizing the Raptor engine as a reference point and employing the discrete Newton iteration method to resolve the equilibrium equations in a fixed-point format. Under different propellants (LOX-LH2, LOX-LCH4, and LOX-kerosene), the static equilibrium characteristics of the FFSC engine were analyzed, and the following conclusions were drawn. The FFSC engine exhibited similar equilibrium results on the oxidizer side, with differences concentrated on the fuel side. Significant differences were identified between the three propellants in the regulation range of the FFSC engine. The regulation range of LOX-LH2 was wider than that of LOX-LCH4 primarily because of the variance in the molecular weight of the fuel-rich gas. Conversely, LOX-kerosene exhibited the narrowest regulatory range, which was attributed to the extremely low value of the oxidizer excess coefficient. The temperature management of preburners relies on regulating the oxidizer excess coefficient, necessitating adjustments to the valve components (main fuel valve (MFV), oxidizer preburner fuel valve (OPFV), and fuel preburner oxidizer valve). The differences among the three propellants were mainly concentrated on the MFV and OPFV.