A knowledge of the modal content prevailing in an engine inlet is of utmost importance for designing the optimum acoustic treatment. This paper describes results of in-flight measurements of circumferential modes as carried out in the untreated and treated inlet of a Fokker 100 aircraft. In order to determine the modes, the inlet was instrumented with a large number of microphones and accelerometers. In addition static pressures in the vicinity of each microphone were measured. It is found that for the untreated inlet the modal energy at 1 BPF is concentrated in a few scattered modes, the modes being adjacent to the mode of the rotor with 22 blades. For treated inlet broadband modal spectra are found which cannot be directly related to the Tyler and Sofrin rule.


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    Title :

    In-Flight Acoustic Mode Measurements in the Turbofan Engine Inlet of Fokker 100 Aircraft


    Contributors:

    Publication date :

    1993


    Size :

    16 pages


    Type of media :

    Report


    Type of material :

    No indication


    Language :

    English




    In-Flight Acoustic Mode Measurements in the Turbofan Engine Inlet of Fokker 100 Aircraft

    Sarin, S. L. / Rademaker, E. R. / American Institute of Aeronautics and Astronautics | British Library Conference Proceedings | 1993





    In-Flight Acoustic Measurements in the Engine Intake of a Fokker F28 Aircraft

    T. Zandbergen / J. N. Laan / H. J. Zeemans et al. | NTIS | 1983