Acoustic panel with non-linear variable percentage of open area

1 . An acoustic panel, comprising:

a first skin comprising an array including a plurality of perforations configured to provide the first skin with a percentage of open area that changes according to a non-linear function as the first skin extends in a first direction, and sizes of at least some of the plurality of perforations varying as the first skin extends in the first direction;

a second skin; and

a cellular core arranged between and connected to the first skin and the second skin, the cellular core comprising a plurality of chambers, each of the plurality of chambers extending between the first skin and the second skin, and each of the plurality of chambers fluidly coupled with the array of plurality of perforations,

wherein the plurality of perforations extend along respective centerlines through the first skin from a first side of the first skin to a second side of the first skin, and respective angles between the centerlines and the first side of the first skin change based on the non-linear function as the first skin extends in the first direction;

wherein a first of the plurality of chambers is arranged between the first skin and of the second skin;

wherein the first of the plurality of chambers includes a first corrugated sidewall;

wherein a second of the plurality of chambers includes a second corrugated sidewall;

wherein the first of the plurality of chambers and the second of the plurality of chambers are neighboring;

wherein the first corrugated sidewall and the second corrugated sidewall separate the first of the plurality of chambers and the second of the plurality of chambers; and

wherein inter-perforation distances between respective neighboring pairs of the at least some of the plurality perforations of the array increase as the array extends in the first direction.

2 . The acoustic panel of claim 1 , wherein

the sizes of the at least some of the plurality of perforations change according to the non-linear function as the array extends in the first direction.

3 . The acoustic panel of claim 1 , wherein the non-linear function is a logarithmic function.

4 . The acoustic panel of claim 1 , wherein the non-linear function is a parabolic function.

5 . The acoustic panel of claim 1 , wherein the non-linear function is a power function.

6 . The acoustic panel of claim 1 , wherein the non-linear function is an exponential function.

7 . The acoustic panel of claim 1 , wherein

the first skin extends axially along and circumferentially about an axis; and

the first direction comprises a component along the axis.

8 . The acoustic panel of claim 1 , wherein

the first direction is a direction of airflow along the first skin during operation of the acoustic panel; and

the percentage of open area decreases as the first skin extends in the first direction.

9 . The acoustic panel of claim 1 , wherein a first of the plurality of perforations has a circular geometry.

10 . The acoustic panel of claim 1 , wherein a first of the plurality of perforations has a non-circular geometry.

11 . The acoustic panel of claim 1 , wherein

a first of the plurality of perforations extends along a centerline through the first skin; and

the centerline is perpendicular to the first side of the first skin.

12 . The acoustic panel of claim 1 , wherein

a first of the plurality of perforations extends along a centerline through the first skin; and

the centerline is angularly offset from the first side of the first skin by an acute angle.

13 . The acoustic panel of claim 1 , wherein the first of the plurality of chambers extends un-interrupted through the cellular core from the second skin to the first skin.

14 . The acoustic panel of claim 1 , wherein the cellular core comprises a septum dividing the first of the plurality of chambers into a plurality of fluidly coupled sub-chambers.

15 . The acoustic panel of claim 1 , wherein at least the first skin, the second skin and the cellular core form a component of an aircraft propulsion system.

16 . An acoustic panel, comprising:

a first skin comprising a plurality of perforations arranged in an array, wherein widths of the plurality of perforations decrease according to a non-linear function as the array extends in a first direction, and wherein inter-perforation distances between respective neighboring pairs of at least some of the plurality perforations increase as the array extends in the first direction;

a second skin; and

a cellular core arranged between and connected to the first skin and the second skin, the cellular core comprising a plurality of chambers, each of the plurality of chambers extending between the first skin and the second skin, and each of the plurality of chambers fluidly coupled with the plurality of perforations;

wherein the plurality of perforations extend along respective centerlines through the first skin from a first side of the first skin to a second side of the first skin, and respective angles between the centerlines and the first side of the first skin change based on the non-linear function as the array extends in the first direction.

17 . An acoustic panel, comprising:

a first skin comprising a plurality of perforations, the plurality of perforations configured to provide the first skin with a percentage of open area that varies according to a non-linear function as the first skin extends in a first direction, and inter-perforation distances between respective neighboring pairs of at least some of the plurality perforations increase as the first skin extends in the first direction;

a second skin; and

a cellular core arranged between and connected to the first skin and the second skin, the cellular core comprising a plurality of chambers, each of the plurality of chambers extending between the first skin and the second skin, and each of the plurality of chambers fluidly coupled with a respective one or more of the plurality of perforations;

wherein the plurality of perforations extend along respective centerlines through the first skin from a first side of the first skin to a second side of the first skin, and respective angles between the centerlines and the first side of the first skin change based on the non-linear function as the first skin extends in the first direction;

wherein a first of the plurality of chambers is arranged between a first portion of the first skin and a second portion of the second skin;

wherein the first of the plurality of chambers includes a first corrugated sidewall;

wherein a second of the plurality of chambers includes a second corrugated sidewall;

wherein the first of the plurality of chambers and the second of the plurality of chambers are neighboring; and

wherein the first corrugated sidewall and the second corrugated sidewall separate the first of the plurality of chambers and the second of the plurality of chambers.