Use of Coupled Euler Lagrange Computational Method to Simulate Ditching Problems

Presentation by Bertrand Langrand, ONERA.

The communication concerns advanced numerical simulations of the transient fluid structure-interaction occurring during aircraft ditching. While the structural model used the Finite Element method, the Arbitrary Lagrangian-Eulerian approach was considered for the fluid model.

This computational method was comprehensively compared using experimental data (local pressures, local strains, and global forces) of guided ditching tests. Numerical results were satisfactory enough to consider further applications to spacecraft and aircraft ditching problems in full scale.

The water impact of the Apollo Command Module was considered because experimental data were available for different impact conditions varying from purely vertical drop tests to oblique (with a high horizontal velocity component) ditching tests with different initial pitch angles and initial velocities.

Finally, the ditching of a generic transport aircraft was simulated. The generic aircraft model was typical of a short- to medium-range commercial passenger twin-engine jet. Different ditching configurations (initial pitch angle, initial horizontal and vertical velocities) were analyzed in terms of impact severity. Additionally, yaw angles were considered in the computations. The influence of the aerodynamic forces (i.e. lift in particular) was studied for some ditching configurations.