The interaction characteristics of shoulder-tail cavities under different pressure ratios and hole ratios

The formation and development of attached cavities on the surfaces of underwater moving vehicles involve complex multiphase flows, which are critical for determining the load characteristics and motion stability of the vehicles. This study utilized experimental methods to investigate the formation process and motion characteristics of these attached cavities. Pressure sensors mounted inside the acceleration tube captured the relationship between cavity evolution and transient pressures. High-speed cameras were employed to observe the shedding morphology of the ventilated shoulder cavity, analyzing the mechanism behind its gas cutoff. The findings reveal that the negative pressure impact during the vehicle's tail exit from the tube is crucial for the gas cutoff of the shoulder ventilated cavity. Additionally, increasing the internal cavity pressure ratio significantly influences the size development of the shoulder cavity. At a constant pressure ratio, different hole ratios have a negligible effect on the axial development of the shoulder cavity. When the number of holes increases and the hole ratio decreases, it promotes the circumferential fusion of the enlarged shoulder cavity and enhances the coverage of gas on the vehicle's surface.