Research on the cavitating vortex structures and attitude stability of a bionic manta-ray vehicle during trans-media motion

To clarify the coupling mechanism between attack angle and cavitation dynamics, this study systematically investigates the cavitation behavior, and attitude characteristics of a bionic manta-ray vehicle during water-exit using numerical simulation. Improved delayed detached eddy model and energy equation, the volume of fluid, schnerr-sauer cavitation model, and overlapping grid technique are adopted to capture the multiphase flow details, while the hydrodynamic coefficients and attitude parameters are quantified. The cavity undergoes a complete nucleation at α ≤ 10°, growth and collapse phenomenon, and the momentum exchange between the vehicle and flow field remains steady. The flow field features three distinct vortex structures—a continuous spanwise wingtip vortex at the wingtip, a coherent hairpin vortex on the lower-middle wing surface, and a dispersed, chaotic shattered vortex further downstream. In contrast, the cavity collapse is advanced with α ≥ 15°, the vorticity intensity in the tail region increases. The pressure disparity across the vehicle cross-section is amplified with increasing α, inducing a localized high-pressure impingement zone on the cavity wall that accelerates cavitation disintegration. This study reveals the regulatory effect of attack angle on cavitation-vehicle interaction, providing a quantitative basis for the attitude control and structural optimization of bionic trans-media vehicles.