| 主权项 |
1. An acoustic structure for reducing noise generated from a source, said acoustic structure comprising:
a honeycomb comprising a first edge to be located closest to said source and a second edge, said honeycomb comprising a plurality of honeycomb walls that extend between said first and second edges, said honeycomb walls defining a plurality of cells wherein each of said cells has a cross-sectional area measured perpendicular to said honeycomb walls; an acoustic barrier located at the second edge of said honeycomb or within at least one of said cells to form an acoustic resonator wherein the depth of said acoustic resonator is equal to the distance between the first edge of said honeycomb and said acoustic barrier; a sound wave guide located in said acoustic resonator, said sound wave guide comprising a solid acoustic guide wall that is impermeable to sound waves, said solid acoustic guide wall having interior and exterior surfaces said solid acoustic guide wall comprising an inlet edge defining a wave guide inlet and outlet edge defining a wave guide outlet wherein said wave guide inlet is closer to said honeycomb first edge than said wave guide outlet and wherein said solid acoustic guide wall divides said honeycomb cell into an inner sound wave channel defined by the interior surface of said solid acoustic guide wall, said wave guide inlet, said wave guide outlet and the portion of said cell wall that extends between said wave guide inlet and the first edge of said honeycomb and an outer sound wave chamber defined by the exterior surface of said solid acoustic guide wall, said acoustic barrier, said wave, guide outlet and said honeycomb wall; a first acoustic septum attached to said wave guide outlet, said first acoustic septum having a top attached to said wave guide outlet and a bottom located nearest the second edge of said honeycomb, said first acoustic septum comprising a sound permeable wall that has a sound damping value and which extends between the top and the bottom of said first acoustic septum to provide a first septum resonator attached to said sound wave guide; and a second acoustic septum that is attached to the bottom of said first acoustic septum, said second acoustic septum having a top attached to the bottom of said first acoustic septum and a bottom located nearest the second edge of said honeycomb, said second acoustic septum comprising a sound permeable wall that has a sound damping value and which extends between the top and the bottom of said second acoustic septum to provide a second septum resonator wherein the acoustic damping value of the wall of said first acoustic septum is different from the acoustic damping value of the wall of said second acoustic septum. |
