Low-Frequency Acoustic Shielding by the Silent Aircraft Airframe
2007; American Institute of Aeronautics and Astronautics; Volume: 45; Issue: 2 Linguagem: Inglês
10.2514/1.19351
ISSN1533-385X
AutoresAnurag Agarwal, Ann P. Dowling,
Tópico(s)Computational Fluid Dynamics and Aerodynamics
ResumoThe 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, boundaryelement 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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