RANS-Fidelity Modeling and Control of Solid Fuel Ramjets

Solid-fuel ramjets (SFRJs) are a promising propulsion technology for high-speed flight, but effective thrust modulation remains an active research challenge. This work investigates thrust control through an active bypass using Reynolds-Averaged Navier–Stokes (RANS) fidelity computations. The objective is to validate a computational fluid dynamics (CFD) framework that balances physical accuracy with computational efficiency, enabling future integration with control systems. Combustion is modeled as volumetric heat addition via a variable source term in the governing equations, with heating rates informed by NASA’s Chemical Equilibrium with Applications (CEA) program. This approach extends prior efforts that relied solely on analytical theory or wall-heating CFD models. Despite its reduced physical and chemical fidelity, the proposed method predicts thrust variations with bypass ratio that align closely with analytical results, which themselves agree with published experimental data. The outcome is a low-cost computational tool suitable for exploring realistic SFRJ thrust-control strategies.