The coupled influences of angle of attack and rotational motion on the cavitation flow around a cylinder vehicle

In this study, the detached eddy simulation (DES) turbulence model coupled with the Schnerr–Sauer cavitation model is employed to numerically investigate the cavity evolution of a rotating underwater vehicle at different rotational speeds and angles of attack. The results reveal the coupled influences of rotation and angle of attack (AOA) on the cavitation flow field characteristics surrounding the vehicle. Specifically, the angle of attack causes the fluid from the upper side of the vehicle to migrate gradually toward the lower side along the body surface, thereby generating two additional streamwise vortices of equal magnitude but opposite direction, leading to a symmetric twin-vortex (TV) structure in the wake. However, the rotation of the vehicle strengthens the vortex with the same rotation direction while weakening that with the opposite direction, thereby resulting in an asymmetric twin-vortex structure, or even a single-vortex structure. Therefore, the internal pressure distribution of the cavity is modified, which subsequently changes the phase transition process between liquid water and vapor. Moreover, cavity evolution analysis shows that the angle of attack predominantly affects the shape of the cavity along its upper and lower surfaces, whereas rotation primarily influences its lateral shape. By modifying the Savchenko empirical formula, a predictive model for the cavity profile under non-zero angle of attack conditions is derived. The analysis demonstrates that the critical wetted angle of attack is inversely proportional to both the cavitation number and the aspect ratio, thereby revealing the constraint relations among aspect ratio, cavitation number, and angle of attack on supercavitating conditions.