Modélisation temporelle des sources acoustiques d'un bâtiment marin ou sous-marin en mouvement dans le champ lointain

National audienceLes sources acoustiques sous-marines de bâtiment marin sont actuellement étudiées de façon individuelle au moyen de modèles numériques pour caractériser finement leur comportement. Cette approche ne répond pas aux problématiques des études acoustiques de champ lointain d'un bâtiment marin entier mobile qui nécessiteraient une modélisation numérique complète. Une démarche de modélisation analytique est proposée dans ce papier pour traiter ces problématiques. Des sources de nature spectrale différente sont modélisées analytiquement pour prédire le champ lointain de pression acoustique d'un bâtiment marin. À partir de ces données, les sources mobiles sont propagées par la théorie des rayons. Enfin, des simulations permettent de valider ces modèles

Localization and Contribution of Underwater Acoustical Sources of a Moving Surface Ship

International audienceWith the advent of new standards for the regulation of acoustic radiation from ships, the measurement of the underwater acoustical radiation of surface ships has become a new concern. This paper proposes array signal-processing methods for loca-lization and estimation of the spectral contributions of underwater acoustic-noise sources of moving surface ships. Beamforming for moving sources is used for localization of the acoustic-noise sources. Then, deconvolution of the point-spread function in the beamforming is performed to estimate the noise-source contributions in this underwater application. Among the classical methods of deconvolution in an aerial environment, the source density modeling method is chosen. However, weighting of the beamform-ing for moving sources is not adapted to the study of large vessels such as ships, which induces the localization of nonphysical sources. A new beamforming weighting strategy is proposed to deal with this issue. In addition, as beamforming for moving sources suffers from poor resolution at low frequencies, a passive synthetic aperture array algorithm is proposed here to successfully improve the resolution. A unique experiment was performed to validate the proposed methods, on Castillon Lake, Alpes-de-Haute-Provence, France, with a towed surface ship and controlled noise sources. In these experiments, the localization performance of the beam-forming for moving sources is improved by the synthetic aperture algorithm. Moreover, the new weighting strategy provides better estimation of the contribution of the sources from the deconvolu-tion results. Index Terms-Beamforming, noise mapping, pass-by noise, underwater acoustics

Acoustic trajectory correction to improve mapping of moving sources

International audienc

Passive synthetic aperture array to improve noise mapping of a moving ship

International audienc

A theoretical and experimental comparison of the deconvolution methods for moving sources

International audienc

WENEMOR: Wind tunnel tests for the evaluation of the installation effects of noise emissions of an open rotor advanced regional aircraft

This paper presents the key objectives from an European Union funded collaborative project investigating the noise installation effects for novel regional advanced aircraft concepts using Open Rotor (OR) propulsion systems. The consortium for the project:WENEMOR, will address the topic by carrying out aero-acoustic measurements in the open test section of a large low speed wind tunnel using a complete reduced scale modular model of different configurations of an aircraft with installed counter rotating open rotor systems operating in both pusher and tractor modes. The principal goal of the project is to assess experimentally the noise shielding effectiveness of classic airframe components for different Open Rotor aircraft configurations. A complete 1/7th scale aircraft has been designed and built for installation in the Pininfarina Aerodynamic and Aeroacoustic Research Center Wind Tunnel. The model has two Open Rotors with a contra-rotating fan at the same scale as the airframe. Various positions of the ORs with respect to the airframe will be tested with noise measurements being performed both in the near and the far field. The test campaign will provide, for the first time in Europe, a comprehensive database on noise installation effects for novel regional advanced aircraft concepts using OR propulsion systems. Two accompanying conference papers present preliminary result