Ditching Numerical Simulations: Recent Steps in Industrial Applications

Abstract

Ditching is an aircraft emergency condition that ends with planned impact of the aircraft on water. The high forward velocity in fixed-wing aircraft ditching affects the aircraft dynamics and its structural response due to complex hydrodynamic effects. Therefore, analysis of ditching impact is particularly relevant to satisfy the airworthiness regulations for modern aircraft. Numerical methods for simulating ditching take advantage of the computational capacity allowing industry to deal with complex models representing the physical phenomena which play a role in ditching. The work performed within this field by means of explicit Finite Element (FE) analysis coupled with Smoothed Particle Hydrodynamics (SPH) is presented. The paper focuses on the analysis of forces acting on the aircraft during ditching: hydrodynamic forces (overpressure and suction forces on the fuselage) and aerodynamic forces. Hydrodynamic loads are the most important forces acting on aircraft during the impact phase because they may affect the airplane’s structural integrity. The numerical models proposed take into account all these aspects to provide a suitable design tool for aircraft manufacturers. Two types of aircraft configurations are presented: a military configuration according to the Airbus Military CN235 aircraft and a civil transport aircraft based on a generic standard body transport aircraft model by the German Aerospace Center (DLR).