A possible way to decrease interaction tone noise of a contra-rotating open rotor is through the application of trailing-edge blowing by reducing the momentum deficit of the front rotor wake, and therefore its interaction with the aft rotor. In this contribution, an assessment of front-rotor trailing-edge blowing is presented for the reduction of contra-rotating open-rotor interaction noise. For this purpose, the German Aerospace Center designed a generic contra-rotating open rotor that has been modified to include trailing-edge blowing at the front rotor blades. With the German Aerospace Center computational fluid dynamics code TAU, unsteady Reynolds-averaged Navier–Stokes simulations have been made of the baseline and the trailing-edge blowing configuration. Subsequently, an aeroacoustic analysis has been performed with the Ffowcs-Williams/Hawkings tool APSIM+ for both configurations. The results show negligible differences of the aerodynamic performance, with significantly lower unsteady loading of the aft rotor when the trailing-edge blowing technique is active. The aeroacoustic results illustrate that the interaction tones are notably ameliorated; that is, a reduction over almost the complete polar angle is seen when trailing-edge blowing is active. With respect to the A-weighted overall sound pressure level, a reduction of approximately 2.5 dBA in the maximum level for the trailing-edge blowing configuration is achieved for the considered geometry. Noise reductions up to 5 dBA are displayed in the up- and downstream directions, which mainly arise from reduced interaction tones caused by the trailing-edge blowing technique. The decreased noise radiation with trailing-edge blowing mainly stems from a reduction in the first two interaction tones.


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    Title :

    Active Flow Control for Interaction Noise Reduction of Contra-Rotating Open Rotors



    Published in:

    Publication date :

    2016




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English



    Classification :

    BKL:    55.50 Luftfahrzeugtechnik / 55.60 Raumfahrttechnik / 55.60 / 50.93 / 55.50 / 50.93 Weltraumforschung
    Local classification TIB:    770/7040