Fig. 1. Schematic diagram of nuclear ramjet system

Fig. 2. Schematic diagram of densely packed single hole hexagonal prism fuel element (color online)

Fig. 3. Diagram of the code calculation logic

Fig. 4. Calculation of physical properties of composite material by Periodic-unit method (color online)(a) Thermal conductivity calculations, (b) Mechanical property calculations

Fig. 5. Main physical properties of co-sintered fuel about UO₂ volume fraction (color online)(a) Thermal conductivity, (b) Young's modulus, (c) Thermal expansion coefficients

Fig. 6. Schematic diagram of module coupling in the code (color online)

Fig. 7. Schematic diagram for boundary conditions for thermal hydraulic and mechanical mechanic solutions (color online)

Fig. 8. Comparison of pressure and temperature changes along the element (color online)(a) Coolant Pressure, (b) Coolant total, static temperature and wall temperature

Fig. 9. Comparison of coolant static pressure along the way at t=0 s (a), t=0.387 s (b), t=0.787 s (c), t=1 s (d)

Fig. 10. Comparison of coolant static temperature along the way at t=0 s (a), t=0.387 s (b), t=0.787 s (c), t=1 s (d)

Fig. 11. Transient heat transfer verification with RELAP5

Fig. 12. Initial relative acceleration (left) and reactivity (right) under small area blockage

Fig. 13. Maximum temperature and maximum von-Mises stress on the inner wall under small area blockage

Fig. 14. The self stabilization process with K_fd of 10 (8%)(a) Relative power, (b) Relative thrust, (c) Relative acceleration, (d) Air-breathing velocity

Fig. 15. The self stabilization and instability processes (20%) with K_fd of 4.0 and 4.1(a) Relative power, (b) Relative thrust, (c) Relative acceleration, (d) Air-breathing velocity

Fig. 16. Variations of initial state parameters with blockage position under small area blockage conditions (color online)

Fig. 17. Variations of initial state parameters with blockage position under global blockage conditions (color online)

Fig. 18. Propulsion acceleration at different initial speeds