The use of an Active Twist Rotor system to provide both vibration reduction and performance enhancement has been explored in recent analytical and experimental studies. Effects of active-twist control on rotor noise, however, bad not been determined. During a recent wind tunnel test of an active-twist rotor system, a set of acoustic measurements were obtained to assess the effects of active-twist control on noise produced by the rotor, especially blade-vortex interaction (BVI) noise. It was found that for rotor operating conditions where BVI noise is dominant, active-twist control provided a reduction in BVI noise level up to about 3 dB. However, low frequency noise was found to increase up to 7 dB and vibration levels were usually adversely affected, in some cases doubling the amplitude, for operating conditions favouring minimum BVI noise. Conversely, operating conditions favouring minimum vibration levels affected BVI noise levels, with both increases and reductions on the order of 3 dB, and also incurred low frequency noise increases up to 7 dB. Minimum vibration levels representing a 90 % reduction from baseline loads were observed.


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    Title :

    Acoustic aspects of active-twist rotor control


    Additional title:

    Akustische Aspekte der aktiven Rotorregelung


    Contributors:

    Published in:

    Publication date :

    2004


    Size :

    8 Seiten, 14 Bilder, 10 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English




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