The 'Silent Aircraft Initiative' is a project funded by the Cambridge-MIT Institute (CMI). Its aim is to discover ways of reducing aircraft noise to the point where it would be virtually imperceptible to people outside the airport perimeter in a typical urban environment. The Silent Aircraft airframe has a flying-wing design with a large wing planform and a propulsion system embedded in the rear of the airframe with intake on the upper surface of the wing. In the present paper, boundary-element calculations are presented to evaluate acoustic shielding at low frequencies. Besides the three-dimensional geometry of the Silent Aircraft airframe, a few two-dimensional problems are considered that provide some physical insight into the shielding calculations. Mean-flow refraction effects due to forward-flight motion are accounted for by a simple time transformation that decouples the mean-flow and acoustic-field calculations. It is shown that a significant amount of shielding can be obtained in the shadow region where there is no direct line of sight between the source and observer.


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    Title :

    Low-frequency acoustic shielding by the silent aircraft airframe


    Additional title:

    Abschirmung der niederfrequenten Schallemission durch den Körper eines geräuscharmen Flugzeugs


    Contributors:

    Published in:

    AIAA Journal (online) ; 45 , 2 ; 358-365


    Publication date :

    2007


    Size :

    8 Seiten, 12 Bilder, 15 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English







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