A unified approach is used to derive many of the current formulations for calculation of discrete frequency noise for helicopter rotors and propellers. Both compact and noncompact source formulations are derived. The compact formulations are obtained as the limit of noncompact source results. In particular, the linearized acoustic equations by Hawkings and Lowson, Farassat, Hanson, Woan and Gregorek, Succi, and Jou are derived in this paper. An interesting thickness noise formula by Isom and its recent extension to the near field by Ffowcs Williams are also presented. The paper includes some comparisons of measured and calculated acoustic pressure signatures and spectra for an advanced propeller. The theoretical results are obtained using a computer program developed by the author and P.A. Nystrom. (Wassmann)


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    Title :

    A collection of formulas for calculation of rotating blade noise - compact and noncompact source results


    Additional title:

    Eine Formelsammlung zur Berechnung des Geraeusches rotierender Schaufelblaetter - Ergebnisse kompakter und nichtkompakter Quellen


    Contributors:

    Published in:

    Publication date :

    1980


    Size :

    13 Seiten, 4 Bilder, 23 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English