Simulation & emergency ditching in the SARAH project

Watch the video to see these steps in action, including the wave tank testing phase

 

• SARAH project presentation video

Development and improvement of numerical tools in this project

This project aims to improve the digital tools used to simulate emergency ditching, by proposing fast and accurate simulation tools for the engineers. These tools are crucial for the design phase of aircrafts (fixed-wing aircrafts as well as helicopters), guaranteeing increased safety while preserving flight performance.

Specifically, two types of numerical tools are required:

• The so-called "low-fidelity" models delivering results with moderate accuracy but allowing very short computational times, which represents an significant advantage for the designers.
• The so-called "high-fidelity" tools proposing a much more accurate prediction of the different physical phenomena involved, but which may require significant computational times.

Within the SARAH project, it was decided to calibrate the low-fidelity models through the results obtained using the high-fidelity tools.

Contribution of the simulations to the design of experiments

Another important part of the project concerns the experiments involving free surface impacts of fixed-wing aircrafts (carried out at the CNR-INM in Rome) and helicopters (carried out in the large wave tank at Centrale Nantes). The high fidelity tools are also used to design the experimental devices (to size the structures and the sensors, and to provide the expected kinematics of the aircraft mockups during the experiments).

In return, to ensure the validity of the numerical models, the simulation results are systematically compared with the experimental ones (impact forces, local pressure, trajectories etc).

Among the high-fidelity tools selected for this project, the SPH-flow software - jointly developed by LHEEA at Centrale Nantes, CNR-INM in Rome and NextFlow Software - is used to simulate these violent free surface impacts. This innovative software is based on the meshless Lagrangian method “Smoothed Particle Hydrodynamics” (SPH). The above video example presents the SPH simulation of a helicopter impact in regular waves, reproducing one of the various experimental impacts performed in the wave tank at  Centrale Nantes during the project.

The research leading to these results has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 724139.