The noise pollution of aircraft cabins results in an unwanted limitation of the passengers comfort, and recurrent exposure to high noise levels can cause serious diseases. In order to reduce the noise exposure of these lightweight structures, passive as well as active methods can be applied. To achieve a noticeable improvement of the acoustic comfort the interior noise sources have to be identified. This proves to be difficult particularly at frequencies below 500 Hz. To localize acoustic hot spots, i.e. the main sources in the structure where sound is transmitted into the cabin, several techniques have been established, ranging from simple sound pressure or intensity measurements to more advanced methods such as Beamforming, Near-Field Acoustical Holography (NAH), Inverse Boundary Element Method (IBEM), or Least-Squares Method (LSM). An up to date overview can be found in the literature. Most of these techniques, however, are either highly ineffective or demand creating artificial free-field conditions to avoid standing waves. A new approach, based on the Inverse Finite Element Method (IFEM), reconstructs the spatial distribution of sound pressure and particle velocity from pressure measurements taken inside the cabin. This procedure has been validated in 2D and 3D simulation as well as a 2D experiment.
Noise source identification in a cross-section of a long-range airliner by means of the inverse finite element method
2009
4 Seiten, 5 Bilder, 9 Quellen
Aufsatz (Konferenz)
Englisch
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