Numerical Analysis of Water-Exit Characteristics of Tandem Twin-Rotor Aerial-Aquatic Vehicle

Aerial-aquatic vehicles(AAV) have broad engineering application prospects due to their ability to perform cross-medium tasks between sea and air and have become a current research hotspot. The shape design of AAVs is crucial for balancing their adaptability in both water and air media, and it significantly affects their stability during cross-medium operations. This paper, considering the characteristics and application requirements of cross-medium navigation, proposes a AAV with a tandem twin-rotor aerial power configuration instead of the traditional quad-rotor or even hex-rotor, forming an elongated fuselage to achieve better hydrodynamic performance. Numerical analysis of the cross-medium dynamic water-exit process of this vehicle shows that the exit angle and speed have a significant impact on the water-exit trajectory and attitude. The exit angle should be around 20°, and the exit speed should be around 5 m/s to mitigate adverse outcomes, including water-exit failure due to a large wetted area from a lower speed or increased deflection angle and torque peak from a higher speed, as well as water-exit failure due to a lower exit angle or instability and improper attitude affecting timely switching between water and air modes from a higher exit angle.