For an over-the-wing/under-the-wing engine configuration on an airplane, the noise produced by the upper jet flow is partially reflected by the lower jet. An analysis has been performed which can be used to predict the distribution of perceived noise levels along the ground plane at take-off for an airplane which is designed to take advantage of the over/under shielding concept. Typical contours of PNL, the shielding benefit in the shadow zone, and the EPNL values at 3.5 nautical miles from brake release as well as EPNL values at sideline at 0.35 nautical miles have been calculated. This has been done for a range of flow parameters characteristic of engines producing inverted velocity profile jets suitable for use in a supersonic cruise vehicle. Reductions up to 6.0 EPNdB in community noise levels can be realized when the over engines are operated at higher thrust and the lower engines simultaneously operated with reduced thrust keeping the total thrust constant.


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    Title :

    Twin jet shielding


    Contributors:

    Conference:

    American Institute of Aeronautics and Astronautics, Aeroacoustics Conference ; 1979 ; Seattle, WA


    Publication date :

    1979-03-01


    Type of media :

    Conference paper


    Type of material :

    No indication


    Language :

    English




    Twin-Jet Shielding

    S. P. ParthaSarathy / R. F. Cuffel / P. F. Massie | AIAA | 1980




    Twin jet noise shielding for a supersonic cruise vehicle

    CLAUSS, JR., J. / WRIGHT, B. / BOWIE, G. | AIAA | 1979


    Twin-Jet Noise Shielding for a Supersonic Cruise Vehicle

    J. S. Clauss B. R. Wright / G. E. Bowie | AIAA | 1980