This paper describes a hybrid technique that combines Statistical Energy Analysis (SEA) predictions for structural vibration with acoustic modal summation techniques to predict interior noise levels in rotorcraft. The method was applied for predicting the sound field inside a mock-up of the interior panel system of the Sikorsky S-92 helicopter. The vibration amplitudes of the frame and panel systems were predicted using a detailed SEA model and these were used as inputs to the model of the interior acoustic space. The spatial distribution of the vibration field on individual panels, and their coupling to the acoustic space were modelled using stochastic techniques. Leakage and nonresonant transmission components were accounted for using space-averaged values obtained from a SEA model of the complete structural-acoustic system. Since the cabin geometry was quite simple, the modelling of the interior acoustic space was performed using a standard modal summation technique. Sound pressure levels predicted by this approach at specific microphone locations were compared with measured data. Agreement within 3 dB in one-third octave bands above 40 Hz was observed. A large discrepancy in the one-third octave band in which the first acoustic mode is resonant (31.5 Hz) was observed. Reasons for such a discrepancy are discussed in the paper. The developed technique provides a method for modelling helicopter cabin interior noise in the frequency mid-range where neither FEA nor SEA is individually effective or accurate.


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    Title :

    A hybrid SEA/modal technique for modeling structural-acoustic interior noise in rotorcraft


    Additional title:

    Eine hybride SEA/Modal-Technik zur meßtechnischen Erfassung struktur-akustischer Innengeräusche in Hubschrauberkabinen


    Contributors:

    Published in:

    Publication date :

    2003


    Size :

    7 Seiten, 10 Bilder, 19 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English




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