In the context of airborne-noise transmission through an aircraft fuselage, a mathematical model is presented for sound transmission into a stiffened cylindrical shell. The stiffening effect of the ring frames and stringers is approximated by a 'smeared'-stiffener theory which includes the eccentricity of the stiffeners. Numerical results are presented for a typical narrow-bodied jet in cruising flight. A comparison is made between noise transmission into a monococque shell and into a stiffened shell. The stiffeners are shown to greatly increase TL for small incidence angles, so that the effective 'window' for noise transmission is restricted to the neighborhood of normal incidence. Flow is shown to increase TL for sound waves propagating 'upstream' against the flow. Stiffeners are also shown to raise the ring frequency at which a dip in cylinder TL occurs. Limitations of the 'smeared'-stiffener theory are also discussed.


    Access

    Access via TIB

    Check availability in my library


    Export, share and cite



    Title :

    On sound transmission into a stiffened cylindrical shell under flight conditions


    Contributors:

    Conference:

    Aero-Acoustics Conference ; 1976 ; Palo Alto, CA


    Publication date :

    1976-07-01


    Type of media :

    Conference paper


    Type of material :

    No indication


    Language :

    English


    Keywords :