Numerical simulation of dynamic performance of trans-media unmanned vehicle during vertical take-off from water

  Objectives  This paper aims to study the kinetic and dynamic characteristics of an trans-media unmanned vehicle during vertical take-off from water.

  Methods  Its dynamic performance during the trans-media process from water to air is numerically simulated on the basis of the viscous computational fluid dynamics (CFD) approach combined with the overset grid technique, multiple degrees of freedom and dynamic fluid body interaction (DFBI) motion model.

  Results  The results show that in order to pull the vehicle up, the air propeller rotation speed should be higher than the speed at the same pull force provided by a single propeller. As the main movement of the vehicle is vertically upward, the coupling of the air propeller downwash flow velocity and the fuselage of the vehicle leads to the "quick bowing" phenomenon.

  Conclusions  To ensure smooth take-off, a manual or automatic control program should be added to adjust the tilt angle of the thrusters in real time during the take-off process. This study provides a powerful evaluation method for the optimal design and control of trans-media unmanned vehicle in the future.