Thermal-acoustic sections for an aircraft

摘要

Embodiments of thermal-acoustic sections for an aircraft for reducing noise along an acoustic path produced from an acoustic source are provided herein. The thermal-acoustic section comprises a first porous layer having a first characteristic acoustic impedance. A second porous layer is disposed adjacent to the first porous layer and has a second characteristic acoustic impedance that is greater than the first characteristic acoustic impedance. The thermal-acoustic section is configured to be positioned along the acoustic path such that at least a portion of the noise from the acoustic source is directed through the first porous layer to the second porous layer to promote absorption of the noise.

主权项

1. A thermal-acoustic section for an aircraft for reducing noise along an acoustic path produced from an acoustic source, the thermal-acoustic section comprising:
a plurality of juxtaposed porous layers forming a thermal-acoustic stack that has a first outermost portion, a second outermost portion, and a central portion that is disposed between the first and second outermost portions, wherein the thermal-acoustic stack is configured to be positioned along the acoustic path such that the noise from the acoustic source is incident to the first outermost portion, and wherein the first outermost portion has a first relatively high characteristic acoustic impedance that is effective to reflect a substantial portion of the noise away from the thermal-acoustic stack and to allow a transmitted portion of the noise to enter the thermal-acoustic stack, and wherein the thermal-acoustic stack has a gradually decreasing characteristic acoustic impedance from the first outermost portion to the central portion and a gradually increasing characteristic acoustic impedance from the central portion to the second outermost portion to promote transmission loss of the transmitted portion of the noise through the thermal-acoustic stack.