Numerical Investigation of Regression Rate and Combustion Characteristics of Solid Fuel Using Counterflow Combustion Simulations

This study investigates the regression rate and combustion characteristics of solid fuel using a simple one-dimensional counterflow diffusion flame analysis.A coupled computational framework was developed by integrating gas-phase and condensed-phase reaction models.Simulation results were validated using regression rates from counterflow combustion experiments.Furthermore, the effects of oxygen concentration, ambient pressure, and oxidizer momentum flux on the combustion behaviors of solid fuel were systematically examined.The predicted regression rates showed good agreement with experimental data across the range of conditions tested in this study, although discrepancies were observed at lower pressures.An increase in oxygen concentration, ambient pressure, and oxidizer momentum flux was found to enhance the regression rate.In particular, the increase in momentum flux and pressure shifts the peak temperature location closer to the fuel surface.This proximity intensifies heat feedback to the solid surface, thereby accelerating the pyrolysis process and increasing the regression rate.Furthermore, the correlation analysis identified the oxygen mass fraction as the most influential of the three examined parameters affecting the regression rate.These findings offer fundamental insight into the pyrolysis and combustion of solid fuel relevant to air-breathing solid fuel propulsion systems.