Numerical Investigation of Regression Rate and Combustion Characteristics of Fuel-Rich Propellant in Ramjet Combustor under Varying Inlet Conditions

The regression rate of solid fuel is a critical performance parameter in solid-fuel ramjets, directly influencing thrust, specific impulse, and range.Therefore, accurate prediction of regression rate is essential for the design and optimization of solid-fuel ramjet propulsion systems.In this study, a coupled numerical framework combining condensed-phase pyrolysis and gas-phase combustion was developed to predict the regression rate and combustion characteristics of a fuel-rich propellant for solid-fuel ramjet applications.The regression rate was computed based on convective heat transfer from the flame and the Arrhenius-type pyrolysis relationship.Systematic analysis was conducted to examine the effects of inlet air mass flux and temperature on fuel regression and combustion performance.The predicted regression rate showed good agreement with experimental data, validating the proposed model.The results revealed that the local regression rate peaked near the reattachment point and gradually decreased downstream.Furthermore, increasing the air mass flux and temperature led to a higher regression rate.A regression rate correlation was derived, demonstrating that both air temperature and mass flux significantly influence the fuel regression rate.