Turbomachine and method of assembly

1 . A turbomachine for an aircraft comprising:

an annular casing formed at least partially of a composite material; and

a fan disposed inside the annular casing and mounted for rotation about an axial centerline, the fan including fan blades that extend radially outwardly toward the annular casing;

wherein the fan includes an average fan chord width of the fan blades (“c”), a diameter of the fan (“D”), a fan pressure ratio (“FPR”), and a redline corrected fan tip Mach number

(

“

M

tip

,

c

(

RL

)

”

)

according to a First Performance Factor (“FPF”),

wherein

FPF

=

[

c

0.15

·

D

]

/

[

[

FPR

-

1

0.4

]

/

M

tip

,

c

(

RL

)

]

-

1.23

,

wherein

m

1

·

[

M

tip

,

c

(

RL

)

-

1.1

]

+

9.14

>

FPF

>

m

2

·

[

M

tip

,

c

(

RL

)

-

1.1

]

,

 and

wherein m 1 is equal to 9.43 when

M

tip

,

c

(

RL

)

is greater than or equal to 1.1 and is equal to tip,c 27.02 when

M

tip

,

c

(

RL

)

is less than 1.1, and

wherein m 2 is equal to 0.87 when

M

tip

,

c

(

RL

)

is greater than or equal to 1.1 and is equal to 3.34 when

M

tip

,

c

(

RL

)

is less than 1.1.

2 . The turbomachine of claim 1 , wherein:

FPF is within a range equal to or greater than −0.8 and equal to or less than 8.4;

M

tip

,

c

(

RL

)

is within a range equal to or greater than 0.8 and equal to or less than 1.5;

a ratio c/D is within a range equal to or greater than 0.1 and equal to or less than 0.3; and

FPR is within a range equal to or greater than 1.2 and equal to or less than 1.6.

3 . The turbomachine of claim 1 , wherein the turbomachine has a gear ratio within a range equal to or greater than 3.2 and equal to or less than 5.0.

4 . The turbomachine of claim 1 , wherein the fan blade includes an airfoil portion made from a polymer matrix composite (PMC) material, a metallic leading edge, a ratio c/D is between 0.16 and 0.21, and the fan has between 16 and 25 fan blades.

5 . The turbomachine of claim 1 , wherein:

the annular casing comprises an annular composite shell extending from a forward flange aft, or downstream, to an aft flange; and

a circumferentially varying thickness portion of the annular casing includes the composite shell.

6 . The turbomachine of claim 5 , further comprising annular forward and aft seams between the annular composite shell and a composite back sheet.

7 . The turbomachine of claim 6 , further comprising the circumferentially varying thickness portion of the annular casing including aftwardly, or downstream, extending lobes, or fingers, of the composite back sheet on the composite shell in the aft seam, wherein a first thickness of the lobes, or fingers, is thicker than a second thickness of the composite shell circumferentially between the lobes, or fingers.

8 . The turbomachine of claim 5 , further comprising an annular composite back sheet spaced radially outwardly of the annular composite shell and an annular filler layer disposed radially therebetween.

9 . The turbomachine of claim 8 , further comprising the filler layer including honeycomb.

10 . The turbomachine of claim 8 , further comprising annular forward and aft seams between the annular composite shell and composite back sheet axially trapping the filler layer between the forward and aft seams.

11 . The turbomachine of claim 10 , further comprising the circumferentially varying thickness portion of the annular casing including aftwardly, or downstream, extending lobes or fingers of the composite back sheet on the composite shell in the aft seam, wherein a first thickness of the lobes or fingers is thicker than a second thickness of the composite shell circumferentially between the lobes or fingers.

12 . The turbomachine of claim 5 , wherein the annular casing comprises a composite fan case, and the turbomachine further comprising a metallic fan casing aft, or downstream, of and bolted to the composite fan case, the metallic fan casing including a metallic fan casing flange bolted to the aft flange.

13 . A turbomachine comprising:

an annular casing formed at least partially of a composite material; and

a fan disposed inside the annular casing and mounted for rotation about an axial centerline, the fan including fan blades that extend radially outwardly toward the annular casing;

wherein the fan includes a fan hub-to-tip ratio (“HTR”), a fan blade count (“BC”), a fan pressure ratio (“FPR”), and a redline corrected fan tip Mach number

(

“

M

tip

,

c

(

RL

)

”

)

according to a Second Performance Factor (“SPF”),

wherein

SPF

=

π

4

⁢

(

1

-

HTR

2

)

/

(

BC

20

)

/

(

FPR

-

1

0.4

)

/

M

tip

,

c

(

RL

)

-

0.97

,

wherein

m

3

·

[

M

tip

,

c

(

RL

)

-

1.1

]

+

2.52

>

SPF

>

m

4

·

[

M

tip

,

c

(

RL

)

-

1.1

]

wherein m 3 is equal to 3.17, and

wherein m 4 is equal to 0.41 when

M

tip

,

c

(

RL

)

is greater than or equal to 1.1 and is equal to 0.55 when

M

tip

,

c

(

RL

)

is less than 1.1.

14 . The turbomachine of claim 13 , wherein:

SPF is within a range equal to or greater than 0.087 and equal to or less than 2.4;

M

tip

,

c

(

RL

)

is within a range equal to or greater than 0.8 and equal to or less than 1.5;

HTR is within a range equal to or greater than 0.2 and equal to or less than 0.4;

FPR is within a range equal to or greater than 1.2 and equal to or less than 1.6; and

BC is within a range equal to or greater than 3 and equal to or less than 18.

15 . The turbomachine of claim 13 , wherein the turbomachine has a gear ratio within a range equal to or greater than 3.2 and equal to or less than 5.0.

16 . The turbomachine of claim 13 , wherein the fan includes an average fan chord width of the fan blades (“c”) and a diameter of the fan (“D”), wherein the fan blade includes an airfoil portion made from a polymer matrix composite (PMC) material, a metallic leading edge, a ratio c/D is between 0.16 and 0.21, and the fan has between 16 and 25 fan blades.

17 . A turbomachine for an aircraft comprising:

an annular casing formed at least partially of a composite material; and

a fan disposed inside the annular casing and mounted for rotation about an axial centerline, the fan including fan blades that extend radially outwardly toward the annular casing;

wherein the fan includes an average fan chord width of the fan blades (“c”), a diameter of the fan (“D”), a fan pressure ratio (“FPR”), and a redline corrected fan tip Mach number

(

“

M

tip

,

c

(

RL

)

”

)

according to a First Performance Factor (“FPF”),

wherein

FPF

=

[

c

0.15

·

D

]

/

[

[

FPR

-

1

0.4

]

/

M

tip

,

c

(

RL

)

]

-

1.23

,

wherein

m

1

·

[

M

tip

,

c

(

RL

)

-

1.1

]

+

9.14

>

FPF

>

m

2

·

[

M

tip

,

c

(

RL

)

-

1.1

]

,

and

wherein m 1 is equal to 9.43 when

M

tip

,

c

(

RL

)

is greater than or equal to 1.1 and is equal to 27.02 when

M

tip

,

c

(

RL

)

is less than 1.1, and

wherein m 2 is equal to 0.87 when

M

tip

,

c

(

RL

)

is greater than or equal to 1.1 and is equal to 3.34 when

M

tip

,

c

(

RL

)

is less than 1.1;

wherein the fan includes a fan hub-to-tip ratio (“HTR”), a fan blade count (“BC”), the fan pressure ratio (“FPR”), and the redline corrected fan tip Mach number

(

“

M

tip

,

c

(

RL

)

”

)

according to a Second Performance Factor (“SPF”),

wherein

SPF

=

π

4

⁢

(

1

-

HTR

2

)

/

(

BC

20

)

/

(

FPR

-

1

0.4

)

/

M

tip

,

c

(

RL

)

-

0.97

,

wherein

m

3

·

[

M

tip

,

c

(

RL

)

-

1.1

]

+

2.52

>

SPF

>

m

4

·

[

M

tip

,

c

(

RL

)

-

1.1

]

wherein m 3 is equal to 3.17, and

wherein m 4 is equal to 0.41 when

M

tip

,

c

(

RL

)

is greater than or equal to 1.1 and is equal to 0.55 when

M

tip

,

c

(

RL

)

is less than 1.1.

18 . The turbomachine of claim 17 , wherein:

FPF is within a range equal to or greater than −0.8 and equal to or less than 8.4;

SPF is within a range equal to or greater than 0.087 and equal to or less than 2.4;

M

tip

,

c

(

RL

)

is within a range equal to or greater than 0.8 and equal to or less than 1.5;

a ratio c/D is within a range equal to or greater than 0.1 and equal to or less than 0.3;

HTR is within a range equal to or greater than 0.2 and equal to or less than 0.4;

FPR is within a range equal to or greater than 1.2 and equal to or less than 1.6; and

BC is within a range equal to or greater than 3 and equal to or less than 18.

19 . The turbomachine of claim 17 , wherein the turbomachine has a gear ratio within a range equal to or greater than 3.2 and equal to or less than 5.0.

20 . The turbomachine of claim 17 , wherein the fan blade includes an airfoil portion made from a polymer matrix composite (PMC) material, a metallic leading edge, a ratio c/D is between 0.16 and 0.21, and the fan has between 16 and 25 fan blades.