Numerical study on the pulsation characteristics of tail cavities under vertical launching conditions

This study aimed to analyze the pulsation characteristics of tail cavities at different Froude numbers under vertical launching conditions. The improved delayed detached eddy simulation (IDDES), volume of fluid (VOF) model, adaptive mesh refinement (AMR), and overlapping grid technique were adopted to model the pulsation characteristics of the tail cavity. The feasibility of the model for predicting dynamic behaviors was verified by comparing the numerical and experimental results. The results demonstrated that the volume of the tail cavity pulsated periodically. However, the concurrent expansion and contraction in the integral tail cavity resulted in a relative state of cavity volume pulsation. When the expansion rate exceeded the contraction rate, the cavity volume increased, otherwise, decreased. In addition, four flow patterns were observed in the tail cavity: smooth, irregular, hybrid, and cavity-shedding regions. An increase in the Froude number augmented the tail cavity volume and proportion of irregular regions, and reduced the proportion of hybrid regions.