| 摘要 |
2098099 9213339 PCTABS00014 A noise attenuation panel (10) for an aero engine comprises a cellular component (12) having an open-celled structure and presenting a front face for exposure to sound to be attenuated. The component has a frontal region which includes the front face and in which the cell structure provides intercommunicating cells of a predetermined first size and density effective to offer low resistance to the passage of gaseous flow across the front face and to prevent normal ingress of liquids into the component through the front face and a base region in which the cell structure provides intercommunicating cells of a predetermined second size and density effective for sound energy absorption. The frontal region is provided by a facing sheet formed from a porous permeable thermoplastics material produced by powder sintering the material and the base region is formed from an open celled plastics foam. Alternatively, the component is wholly in the form of a plastics foam or is made wholly from a porous permeable thermoplastics material produced by powder sintering the material.
|
