Investigation of Liquid Droplet Flow Behavior in a Vertical Nozzle Chamber

This study aims to better understand the aluminum oxide agglomerates breakup mechanism, consequently determining the best solution for the solid rocket motor (SRM) nozzle erosion problem. Two-phase air-water flow experimental investigation was conducted as a substitute for liquid aluminum agglomerates and exhaust combustion gases. The results show that increasing the exhaust air velocity enhances the droplet's breakup tendency to reduce the average diameter and increase droplet numbers per the testing channel volume. Numerical models were constructed and validated using the experimental results. The percentage error in the droplets’ average diameter and the number is between 6 and 15% and 8 and 18%, respectively. Furthermore, the effect of reducing the liquid surface tension was studied. The results showed that it facilitates water bodies’ separation from the interface surface, because of the reduced bounding forces between surface’s molecules, which enhances the breakup process (0.5–17% increase in the droplets’ average diameter and 4–100% increase in its number) and reduces the droplets impact on the nozzle walls, hence reducing the SRM nozzle erosion problem.