Ditching simulation of aircraft. A comparative analysis of different computational approaches

Kurzfassung

Aircraft manufacturers can apply diverse methods to demonstrate compliance with respect to ditching requirements. Nevertheless, computational numerical approaches in combination with detailed aircraft models allow for the analysis of the global kinematics of the aircraft, and for the investigation of the local airframe structural integrity. The numerical simulation of ditching is very challenging, because the fluid moves at considerably high velocity and the structure undergoes large nonlinear deformations due to high hydrodynamic loads. For this kind of coupled analysis, different numerical methods were used for comparisons, mainly mesh free Lagrangian methods such as the coupled Finite Element-Smoothed Particle Hydrodynamics on one hand or the Arbitrary Lagrangian Eulerian methods on the other hand. The coupling between the SPH and the structure is based on a node to surface contact interface, while the Coupled Euler-Lagrange computational approach uses an embedded contact interface between the fluid (ALE formulation) and the structure. A flexible reinforced bottom-aircraft panel made of a skin, frames and stringers in aluminium alloy and modelled with bi-linear quadrangular shell elements under guided ditching conditions was considered in previous work. Detailed results obtained for the different computational approaches are compared here in terms of global and local time histories.