Journal of the Brazilian Society of Mechanical Sciences and Engineering
Print version ISSN 1678-5878
PIRK, Rogerio and SOUTO, Carlos d'Andrade. Implementation of acoustic materials to the VLS-1 Fairing - a sensitivity analysis using SEA. J. Braz. Soc. Mech. Sci. & Eng. [online]. 2012, vol.34, n.1, pp. 82-88. ISSN 1678-5878. http://dx.doi.org/10.1590/S1678-58782012000100011.
Satellite launchers are submitted to severe acoustic loads mainly during lift-off where SPL achieve, at the upper parts, values within the range of 140-160 dB. Such an excitation can damage embedded elements, if energy attenuation measures are not adopted. In view of managing the PLF vibro-acoustic environment, numerical techniques are applied to predict elasto-acoustic behavior. This manuscript presents a numerical study on the design of acoustic insulation for the VLS-1 fairing compartment. An excitation profile based on the literature is applied on a SEA coupled model of this structural-acoustic system and absorbing materials are added to the model. Two parameters of the absorbing material layer are analyzed: thickness and covered area. Two NCT modeling approaches are used to simulate the effect of blanketing the VLS-1 fairing: acoustic materials Biot's parameters, given by the manufacturer, and material samples absorption coefficient, measured in a Kundt Tube. Results show that an increase in the blanket thickness from 7.62 to 12.7 cm results in a TL of 1.7 dB OSPL, while variations of up to 3.0 dB OSPL are calculated if the fairing cavity blanketed area varies from 30% to 100%.
Keywords : statistical energy analysis; acoustic materials; sound attenuation; launchers; fairing.