Abstract
Due to the severe acoustic environment during space vehicle lift off the prediction and mitigation of acoustic levels becomes a vital issue. This paper conforms the engineering background needed to develop a new sound mitigation method for vehicle launchers. The sound propagation within a launch event has been analysed with dedicated CFD, identifying the shock waves and the evolution of the SPL generated. Data analysis of the pressure field surrounding the fairing demonstrates a vertical directivity. On the structural domain, a numerical modelling framework composed of an hybrid FEM/BEM/SEA model has been postulated. The results provide the basis to analyse the mitigation structures proposed. On the acoustic side, two different metamaterial structures are presented, both made of a periodic unit cell of Helmholtz resonators. On the launch pad, the metamaterial partially covers the exhaust channels and provides quasi-perfect broadband sound absorption. On the fairing the metamaterial is added to the existing wall and introduce an absorption peak. These findings provide a noise mitigation technique that has the potential to improve the attenuation efficiency, thus, reducing the acoustic loading and the risk of technical failure during the launch stage.
BibTeX citation
@inproceedings{MaraECSSMET2021,
author = {Mara S. Escartí-Guillem and José Manuel Requena-Plens and Pablo Barriuso Feijoo and Alejandro Cebrecos and Marcos Chimeno-Manguán and Pedro Cobo-Parra and Luis Miguel García-Raffi and Jean-Philippe Groby and Sergio Hoyas and Noé Jiménez and Mario Lázaro and Julien Leng and José Nieto Mocholí and Elena Roibás Millán and Vicent Romero-García and Rubén Picó and Víctor Sánchez-Morcillo and Francisco Simon and Ivan C.S. Ngan},
booktitle = {16th European Conference on Spacecraft structures, Materials \& Environmental Testing (ECSSMET 2021). Online, 23 - 25 March},
editor = {Europeean Space Agency},
isbn = {ISSN: -},
month = {03},
organization = {Europeean Space Agency},
pages = {1-2},
publisher = {Conference Proceedings},
series = {Poster},
title = {Launch sound level characterisation and mitigation: numerical modelling framework and metamaterial proof of concept},
year = {2021}
}