Aerothermodynamic Parametric Analysis of Hypersonic Re-entry Capsules with Passive Decelerators

This study investigates the aerothermodynamic optimization of the Orion Crew Exploration Vehicle (CEV) re-entry capsule through Computational Fluid Dynamics (CFD) to enhance drag reduction and stability while evaluating thermal trade-offs, decreasing the re-entry speed at minimal cost. Three configurations (Baseline, 2-Duct, and 4-Duct) were analyzed across supersonic to hypersonic regimes (Mach 1.4–6). The SST k-ω turbulence model and Two-Temperature (TT) formulation, validated against experimental AEDC Tunnel 9 data and DSMC benchmarks, demonstrated heat flux predictions within 5% accuracy. Results revealed that duct integration reduced drag coefficients by an average of 2.07% (2-Duct) and 2.86% (4-Duct), peaking at 3.55% for the 4-Duct model at Mach 1.4. However, hypersonic conditions (Mach 6) amplified surface heat flux by 69% for the 4-Duct configuration, averaging 28.6% across all cases, attributed to intensified shock interactions and turbulent wakes. Notably, at Mach 1.4, heat flux decreased by 29.4% (2-Duct) and 17.7% (4-Duct), highlighting regime-dependent trade-offs. The findings underscore a critical design paradox: passive drag reduction exacerbates thermal loads in hypersonic flows. This work advances the understanding of ducted geometries for re-entry capsules. The validated framework provides a foundation for optimizing next-generation re-entry vehicles, balancing aerodynamic efficiency with thermal resilience for safer crewed missions.