Conjugate heat transfer and thermal stress characteristics of scramjet ceramic regenerative cooling channels at different aspect ratios

Regenerative cooling structures based on new high-performance ceramics hold promise for addressing thermal protection challenges in high-Mach-number scramjet engines. However, due to the inherent mechanical weaknesses of ceramics, it is crucial to consider coupled thermal-mechanical effects in research. To accurately simulate the thermal load on the ceramic cooling structure, this study developed a three-dimensional conjugate heat transfer numerical model coupling a simplified supersonic combustor with a kerosene regenerative cooling channel. The results show that appropriately increasing the channel aspect ratio ( κ ) can simultaneously reduce the peak temperature of the inner and outer walls by more than 200 K. Comparative analysis of six aspect ratios ( κ =1∼12) indicates that under Ma 8 flight conditions, optimal heat transfer performance for the ceramic cooling structure is achieved at κ =6. However, further thermoelasticity calculations reveal that increasing the aspect ratio significantly raises thermal stress, making the ceramic structure highly susceptible to thermal stress damage. To resolve the prominent conflict between enhanced heat transfer and structural safety, this study proposes an optimization strategy that simultaneously accounts for the synergistic variation of the aspect ratio and ceramic thermal conductivity, achieving a dual reduction in peak kerosene temperature and maximum thermal stress.