Abstract: The influence of the initial conditions on the water landing performance of an amphibious aircraft is investigated by solving the unsteady Reynolds-averaged Navier-Stokes equations coupled with the standard k-ω turbulence model. During simulation, the relationship among the aircraft, the mesh and the air-water interface is managed by the Arbitrary Lagrangian-Eulerian method with an improved computational mesh generation strategy. Based on this, the effects of the initial conditions including the incident angle, the descent velocity and the horizontal velocity on the landing performance are explored, meanwhile considering changes in parameters such as the overloads on the cockpit and the center of gravity, aerodynamics, hydrodynamics, the pitching angle and vertical displacement for the aircraft water landing process. Numerical results show that the amphibious aircraft experiences a relatively moderated load due to the increase of the initial incident angle. The cockpit experiences a much larger vertical overload value compared with that of others when the extreme value of pitching moments occurs. Furthermore, the overload of the aircraft reduces significantly as the descent velocity decreases. A linear relationship can be clearly established between the overloads on the center of gravity and the square of the downward velocities. Moreover, to obtain better landing performance on water, the aerodynamic lift caused by the horizontal flight velocity should be slightly larger than the aircraft gravity before landing.

Key words: amphibious aircraft, finite volume method, volume of fluid models, arbitrary Lagrangian-Eulerian method, overload of cockpits