Une méthode d'analyse des problèmes acoustiques externes et internes en aéronautique. Illustrations dans le cas du véhicule spatial Hermes

Abstract
To solve aeronautical and aerospace industrial vibro-acoustic problems (cabin noise, panel radiation, vibration environment, ...) Dassault Aviation has developed an attractive computation strategy. Actually, in the so-called 'Coupling Finite Element and Singularity method' (CFES), each field (structure dynamics, interior acoustics, exterior acoustics) is calculated independently from one another with the best suitable methods. As there is no reason to have coincidence between these optimized subsystems, elasto-acoustic couplings are performed via an original technique based upon the introduction of interfacing models both independent of structure and acoustic approximations. The effectiveness of this approach is fully illustrated through the studies undertaken for Hermes spacecraft project. Severe acoustic loadings were identified (engines noise at launch, take off transonic aeronoise, phases of maximum dynamic pressure during atmospheric reentry) which may have caused damage to the 'nose' of this glider. Thus, taking profit on our computational organisation, numerical simulations were done considering a mechanical model (of the nose) coupled with the inside acoustic cavity. This made possible numerous sensitivity analyses from the study of correlation length effect to the determination of equivalent loads for shaker tests on a scaled-down model.