The semi empirical scaling law by Nelson and Morfey [1] predicts the noise generation from constrictions in ducts with low Mach number flows. The results presented here demonstrate that the original model loose accuracy for constrictions of high pressure loss. An extension based on a momentum flux assumption of the dipole forces is suggested and is evaluated against measurement results for orifice geometries of higher pressure loss than earlier evaluated. A prediction model including constrictions at flow duct terminations is also suggested. Improved accuracy for the predictions of the new model are found for orifice geometries of both high and low pressure loss inside and at end of ducts. The extended model is finally evaluated by measurementson a regular ventilation air terminal device.


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    Title :

    Revisiting the Nelson–Morfey scaling law for flow noise from duct constrictions



    Published in:

    Publication date :

    2015




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English



    Classification :

    BKL:    33.12 Akustik / 50.36 Technische Akustik / 53.79 Elektroakustik, Tonstudiotechnik / 58.56 Lärmschutz, Erschütterungsdämpfung / 50.32 Dynamik, Schwingungslehre
    Local classification TIB:    275/3425



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