The acoustic analogy is used to derive far field noise radiation equations for high speed propellers in flight via a helicoidal surface representation. Quadrupole terms are included and discussed but only the linear sources are studied in detail. The frequency domain results clarify the role of acoustic noncompactness (noise cancellation due to finite chord and span effects). Nondimensional parameters arising from the analysis give design guidance by showing the potential for noise reduction due to changes in airfoil section and blade sweep, twist and taper as functions of operating conditions. Conventional propellers are shown to be relatively insensitive to variations in blade design. However, advanced turbo-propellers (Prop-Fans) currently under development are decidedly noncompact because of their high solidity and speed. Examples of chordwise and spanwise cancellation are given illustrating substantial benefits of sweep. (DePo)


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    Title :

    The influence of propeller design parameters on far field harmonic noise in forward flight


    Additional title:

    Der Einfluss der Propellerauslegung auf die Entwicklung der Oberwellenschwingungsgeraeusche beim Vorwaertsflug


    Contributors:

    Published in:

    Publication date :

    1979


    Size :

    17 Seiten, 23 Bilder, 11 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English