Launch sound level characterisation and mitigation: numerical modelling framework and metamaterial proof of concept.
Escartí-Guillem, Mara Salut,
Requena-Plens, José M.,
Feijoo, Pablo Barriuso,
Cebrecos, Alejandro,
Manguán, Marcos Chimeno,
Parra, Pedro Cobo,
Raffi, Luis Miguel García,
Groby, Jean-Philippe,
Calvo, Sergio Hoyas,
Jiménez, Noé,
Navarro, Mario Lázaro,
Leng, Julien,
Mocholí, José Nieto,
Millán, Elena Roibás,
Romero-García, Vicente,
Picó, Rubén,
Sánchez-Morcillo, Víctor J.,
Hidalgo, F. Simón, and Ngan, I. C.S.
In 16th European Conference on Spacecraft structures, Materials & Environmental Testing. Oct 2021
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.