The aerodynamic and subsequent acoustic effects of nonaxial inflow on wide-chord, advanced high-speed propellers are studied by means of a lifting surface theory. Starting from the flow equations for a perturbed, axially subsonic flow, expressions are derived for the pressure and velocity field of a propeller. By using a representation of Green's function in separated, cylindrical coordinates the boundary condition at the hub is naturally incorporated. Application of the boundary condition at the blade surfaces yields an integral equation for the unknown pressure jump distribution over the blades that is solved numerically. The method is applied to study the near-field acoustic effects of propellers in uniform upwash and downwash at low and high speeds. Typical examples show that, for moderate speed, substantial reductions of the side line peak level of the order of 5 dB are possible for the proper amount of downwash. At high speed, however (flight Mach number 0.75, helical tip speed supersonic), downwash does not yield any significant sound reduction.


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    Title :

    Effects of asymmetric inflow on near-field propeller noise


    Additional title:

    Auswirkungen einer asymmetrischen Einlaufströmung auf den Nahfeld-Propellerlärm


    Contributors:

    Published in:

    AIAA Journal ; 34 , 2 ; 251-258


    Publication date :

    1996


    Size :

    8 Seiten, 17 Bilder, 22 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English




    Effects of Asymmetric Inflow on Near-Field Propeller Noise

    Schulten, J.B.H.M. | Online Contents | 1996




    Effects of Asymmetric Inflow on Near-Field Propeller Noise

    Schulten, J. / Confederation of European Aerospace Societies| AIAA | British Library Conference Proceedings | 1995