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Process and device for reducing the spectral line noise inside an aircraft, especially a rotating-wing aircraft, in particular a helicopter

  • US 20010005814A1
  • Filed: 12/07/2000
  • Published: 06/28/2001
  • Est. Priority Date: 12/10/1999
  • Status: Active Grant
First Claim
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1. A process for reducing the spectral line noise inside a rotating-wing aircraft, in particular a helicopter, according to which process the following operations are carried out repetitively and automatically:

  • a) for each of I points Mi, i varying form 1 to I, situated on said rotating-wing aircraft, the value P2mi of a vibratory and/or acoustic parameter which exists at said point Mi is measured, said vibratory and/or acoustic parameter being representative of a vibratory and/or acoustic effect of at least one source of noise of said aircraft;

    b) for each of said I points Mi, a value P1i corresponding to the relation;

    P





    1





    i
    =P





    2





    i
    +

    j=1j=J






    (Tj,i.P





    3





    j
    )


    is measured in real time, in which relation;

    P2i is representative of the value P2mi measured in the absence of active control;

    Tj,i is a value for transferring between the value of a vibratory and/or acoustic parameter existing at the level of a controllable mechanical element (A), and the corresponding value existing at said point Mi; and

    P3j is a value of said vibratory and/or acoustic parameter, due to the action of said mechanical element (A) and dependent on the control of the latter; and

    c) on the basis of the values P1i measured in real time for all the I points Mi, a sum S is calculated, satisfying the relation;

    S=

    i=1i=I






    |P





    1





    i


    |2
    d) said sum S is minimized so as to deduce therefrom control commands for said mechanical elements (A); and

    e) the control commands thus deduced are applied to said mechanical elements (A), wherein, repetitively and automatically, in a preliminary step, the value of at least one reference parameter which is correlated with the noise from said source of noise is measured and, on the basis of said measured value of the reference parameter, a reference signal is determined, and in step d), said sum S is minimized by carrying out filtering with respect to said reference signal determined in said preliminary step.

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