Research on Aerodynamic and Hydrodynamic Performance and Exiting Water Process of a Morphing AquaUAV

The cross media UAV has the advantages of underwater concealment and aerial rapidity，it can achieve good performance both in water and in air. In this paper, a 5.12m long swept wing reconnaissance UAV is designed, which can be vertically launched from water, cruise at Ma number 0.6 in the air (max cruise speed 0.8Ma) and return back to water after completing the mission. A propeller was designed at rear to provide thrust underwater, and retracted inside the fuselage in the air. The conceptual design of AquaUAV is completed, including aerodynamic configuration, propulsion system and pumping-drainage system etc. Moreover, the zero-lift drag coefficient of the UAV was evaluated as 0.015 through CFD simulation at velocity 20m/s. Furthermore, the exiting water process of the simplified model was simulated via unsteady two-phase VOF model at various oblique and velocity. The free surface deformation of water and air were compared with experimental photos, it shows consistent results. Subsequently, drag and pitching moment variation of the model were obtained. Results show that water surface developed a lump obviously when the body’s head is out of water, both the drag and moment changed sharply during the short exiting water process.