Aircraft side wall with improved low-frequency sound insulation using a lining panel with Helmholtz resonators

The continuous development of aircraft engines aims to reduce fuel consumption by increasing the bypass ratio. However, an increased bypass ratio changes the sound emission of the engine, such that the sound spectrum inside the cabin can be dominated by low frequency tones with high sound pressure levels, penetrating more efficiently the current cabin wall than sound of higher frequencies. Thus, the comfort level of the passengers could be adversely affected. This contribution presents a new side wall panel design that is capable to significantly increase the transmission loss of low frequency tones. The rear side of the lining is fully covered by a resonator system of a cantilever integrated into a Helmholtz resonator. With this approach, the lining with resonators can be tuned with respect to two resonance frequencies to improve the sound transmission loss of the cabin wall. A transfer matrix for the Helmholtz resonator panel is derived and the transmission loss of the proposed side wall design is determined. The analytically calculated transmission loss is compared to numerical and experimental results obtained under diffuse field conditions

Subjects

Bandwidth

Double wall

Helmholtz resonators

Transmission loss

Vibration resonators

More Funding Information

Bundesministerium für Wirtschaft und Energie, grand number: 20K1511D

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Aircraft side wall with improved low-frequency sound insulation using a lining panel with Helmholtz resonators