Coupled Thermo-Structural Analysis of Uncooled Rocket Nozzle Metal Case

This study conducted a comprehensive coupled thermo-structural analysis of an uncooled rocket nozzle to investigate the temperature and stress distribution within the nozzle construction. The design of the nozzle incorporated isomolded graphite inserts from the convergent region to the throat, with a casing made of carbon steel JIS S45C. The simulation, accounting for maximum operating conditions, modeled pressures reaching 6 MPa and temperatures up to 2800 °C in the combustion chamber. Temperature-dependent material properties were integrated into the simulation to accurately define failure criteria. The results indicated that thermal stress, arising from temperature fluctuations across the casing's thickness, predominantly affects the outer wall of the nozzle casing. The highest temperature peak and corresponding thermal stress were observed in the diverging section of the nozzle. However, the stress in this region is secondary and can be mitigated due to the inherent resilience of steel to thermal stress. These findings suggest potential areas for improving the structural integrity and failure resistance of rocket nozzles, which could inform future design and material selection efforts.