Abstract: Based on classical nucleation theory, temperature and solid volume fraction of Al₂O₃ droplet during solidification are investigated. The solidification rate under different conditions during nucleation and recalescence is calculated. On the basis of the above discussion, the solidification process of Al₂O₃ droplet in the secondary combustion chamber of solid rocket ramjet is analyzed. The result shows that initial particle size and ambient temperature have a great effect on solidification rate. The higher the ambient temperature is, the more slowly the droplet solidifies. We also find that Al₂O₃ has different states at different regions in the secondary combustion chamber of solid rocket ramjet. The state of Al₂O₃ is mostly liquid or solid-liquid mixture in the head-end of secondary combustion chamber, thus the solid volume fraction is smaller. Moreover, the state of Al₂O₃ is mostly solid or solid-liquid mixture, and the solid volume fraction is larger in the low temperature regions.

Key words: solid rocket ramjet, secondary combustion chamber, solidification, nucleation, recalescence