Far-field acoustic data for a model helicopter rotor have been gathered in a large open-jet, acoustically treated wind tunnel with the rotor operating in hover and out of ground-effect. The four-bladed Boeing 360 model rotor with advanced airfoils, planform, and tip shape was run over a range of conditions typical of today's modern helicopter main rotor. Near in-plane acoustic measurements were compared with two independent implementations of classical linear theory. Measured steady thrust and torque were used together with a free-wake analysis (to predict the thrust and drag distributions along the rotor radius) as input to this first-principles theoretical approach. Good agreement between theory and experiment was shown for both amplitude and phase for measurements made in those positions that minimized distortion of the radiated acoustic signature at low-frequencies.


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    Title :

    Prediction and measurement of low-frequency harmonic noise of a hovering model helicopter rotor


    Contributors:

    Conference:

    AHS Annual Forum ; 1989 ; Boston, MA, United States


    Publication date :

    1989-01-01


    Type of media :

    Conference paper


    Type of material :

    No indication


    Language :

    English


    Keywords :




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