Computational studies on the effect of water impact on an unmanned air vehicle

Abstract

<p>Computational Fluid Dynamics (CFD) was used in conjunction with Finite Element Analysis (FEA) to simulate the water splashdown and effects thereof on an Unmanned Air Vehicle (UAV). The CFD simulation utilized time-accurate finite-volume code to model both "compressible" and "incompressible" ensemble averaged Navier-Stokes equations. The model also incorporated the volume of fluid method to track the air-water interface, and dynamic cell remeshing to move the UAV body through the computational domain. The model was verified by comparing pressure histories with experimental test data. There was good agreement in character and magnitude of these results, with some deviance in the inlet duct of the aircraft. Tests were performed for various drop heights, yielding different impact velocities. Finally, the CFD results were used to perform an FEA study of the effect on the inlet close-off door. As confirmed by experimental test hardware, the FEA model predicted that the door would permanently deform, requiring reinforcement to the support arm.</p>