Numerical investigation of the fluid dynamic properties in ventilated cavitation around an underwater vehicle

Ventilated cavitation is a complex flow phenomenon that involves multi-phase flow, coupled vortex evolution, and turbulent pulsation. This paper employs the large eddy simulation method to systematically investigate the ventilated cavitation flow of an underwater vehicle equipped with a disk cavitator. The results indicate that the ventilation rate (Cq) significantly influences the cavity morphology and drag. It was observed that the closure mode of the ventilated cavity transitioned consistently with increasing Cq under Fr = 10.2, shifting from a reentrant jet to a twin vortex tube. Additionally, the key factors contributing to the formation of the twin vortex tube have been identified, which is the effects of gravity and local adverse pressure gradient. Furthermore, mechanical properties in twin vortex closure mode were analyzed, finding that the vehicle's drag and stability were influenced by the shedding of vortex structures and the dynamic deformation of the gas–liquid interface. Finally, the distribution characteristics of the modal vortex force were analyzed using the proper orthogonal decomposition method, providing a theoretical foundation for optimizing the lift and drag distribution of the vehicle.