Advances in numerical ditching simulation of flexible aircraft models

Abstract

This paper deals with explicit numerical simulation of fixed-wing aircraft ditching using a coupled approach of Smoothed Particle Hydrodynamics and Finite Elements. Particular focus is put on recent advances toward simulation of flexible full aircraft models, which comprises significant challenges with respect to the numerical efficiency as well as the model complexity. First, the pursued numerical approach is briefly presented. In order to deal with aforementioned challenges, an automated modular tool, which generates numerical models and launches ditching simulations, is presented. The paper provides a brief explanation of state-of-the-art aircraft as well as fluid modelling techniques used and furthermore presents an integrated model that computes aerodynamic loads during the simulation. The developed tool is used to conduct various numerical studies. First, the improved efficiency of such simulations over the state of the art is shown. Next, results of parameter studies are presented, demonstrating the effects of impact conditions on the aircraft motion. Finally, the structural deformation experienced during ditching of a detailed finite element aircraft model is analysed and its effects on the aircraft motion are discussed.

KEYWORDS:

• Aircraft ditching
• explicit numerical simulation
• fluid–structure interaction
• SPH-FE approach
• structural flexibility
• process chain

Acknowledgements

The authors would like to especially thank Dr Paul Groenenboom (ESI Group) for his continuous support regarding software developments and Luis Benítez Montañés (Airbus Defence and Space) for supporting the development of the aerodynamics sub-routine. Contributions by Maria Inês Costa Cadilha and Joel Gomes (Instituto Superior Técnico) are highly appreciated.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. Here the formulation of Monaghan [25,26] is adopted.

2. The tools involved to compute the aerodynamic coefficients are LIFTING_LINE and POLINT [20], which are based on Prandtl lifting line theory.

Additional information

Funding

Most of the work leading to the results presented has received funding from the European Commission's Seventh Framework Programme under grant agreement no FP7-266172 and was performed within the project SMAES – SMart Aircraft in Emergency Situations.