Experimental measurements on a model scale helicopter in a wind tunnel have shown that the levels radiated in the direction of flight are strongly dependent on the fuselage angle to the mean flow. Here a theoretical model is derived to explain these measurements using unsteady thickness noise as the principle source mechanism. The model includes the effect of fuselage wake turbulence which is convected through only the lower sector of the rotor disk. This causes spectral peaks which do not occur at blade passing frequencies, but rather at frequencies associated with convected flow inhomogeneities. The results are compared with measurements and show good agreement over a range of fuselage angles and mean flow speeds.


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    Title :

    The prediction of helicopter tail rotor noise on the flight path


    Contributors:

    Publication date :

    1987-10-01


    Type of media :

    Conference paper


    Type of material :

    No indication


    Language :

    English


    Keywords :



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