Highly Flexible Aircraft Flight Dynamics using CFD

ifasd2024 Tracking Number 62

The present study has been carried out in collaboration with Airbus, in the frame of the French DGAC funded project MAJESTIC. This project is devoted to the study of the civil aircraft high aspect ratio adaptive wing (HAR). Today, the typical aspect ratio value of a civil aircraft wing is about 9. In MAJESTIC, several versions of the XRF1 Airbus model of aspect ratio 12 and 14 are evaluated. For such configurations, wing flexibility becomes prominent and aeroelastic effects have to be taken into account in order to properly analyse the aerodynamic performances of the aircraft. Moreover, structural integrity due to strong aeroelastic effects has to be assessed, in such cases as flutter, control surfaces reversal and gust response. Aeroelastic design is crucial in order to deliver a configuration fully satisfying the multi-disciplinary constraints and global performances needed to meet drastic climate impact reductions objectives. In addition, due to the large wing span, the coupling of structural modes of low frequency and flight dynamics modes comes in the scope of the study. The present paper focuses on the development of a numerical CFD methodology for the simulation of the flight dynamics of the flexible aircraft, in open loop and in closed loop as well (Figure 1). To do so, a modular environment is developed to couple the ONERA CFD solver elsA with python modules implementing several simulation capabilities: prescribed complex trajectory, 6 DoFs flight dynamics, structural linear dynamics, control surfaces actuations, control laws. The basic assumptions and numerical features of the developed environment are presented along with a reminder of the unsteady deformable capabilities of the elsA code, and several applications performed in the frame of the MAJESTIC project on the HAR XRF1 configurations are shown. In particular the topic of the simulation of active Gust Load Alleviation is examined. Perspectives are given on the future extension of the approach to the accounting for non-linear structural behaviour, and the possible use of other CFD solver such as CODA or the ONERA next generation solver SoNICS.