DEVELOPMENT OF FULL SCALE RAMJET NOZZLE WITH C/SiC CERAMIC MATRIX COMPOSITE

In order to fulfill the requirement, there exists challenging problems in the development of C/SiC Ceramic Matrix Composite for the ramjet nozzle due to its harsh thermal-chemical and mechanical working environment. Investigation has been performed to develop the full scale ramjet nozzle. Firstly, the low pressure failure of the hydraulic pressure for the C/SiC nozzle is due to both the low strength low density of throat and stress concentration of throat. Effective measures have been taken to solve this problem. Secondly, the three-dimensional needled C/SiC composite nozzle can work safely under the oxygen-rich combustion environment of the ramjet for long test duration. No obvious damage and ablation were observed in the entrance and divergent section of the composite nozzle. Thermochemical ablation is the dominated ablation mechanism for the nozzle throat. The severest ablation and damage was founded in the convergent section of the nozzle. Thermochemical ablation and thermal-mechanical erosion were suggested as ablation mechanism for the convergent section of the nozzle. Hence for the safety and reliability of the nozzle, design has been modified to accommodate different working conditions. Lastly, the convergent angle of nozzle has little effect on solid phase deposition property. Both the shock wave in the divergent section of nozzle, in which the gas of divergent section is under-expanded, and C/C-SiC composite of ramjet combustor have significant effects on solid phase deposition property under the current ramjet working conditions.