Grating for the formation of a reverse flow of an aircraft turbofan engine
A grating for the formation of a reverse flow of a turbofan engine and comprising fins of a first type having a curved profile whose rounding is oriented aft and whose center of curvature is forward relative to the fin of the first type, fins of a second type having a curved profile whose rounding is oriented aft and whose center of curvature is forward relative to the fin of the second type. In this grating, each fin of one of the two types is inserted between two fins of the other type moving from forward to aft and the cord of the fins of the second type is smaller than the cord of the fins of the first type.
1. A grating for forming a reverse flow of a turbofan engine having a forward longitudinal end and an aft longitudinal end and a lateral width, the grating comprising:
fins of a first type having a curved profile when viewed in a lateral direction relative to the grating, a rounding of the curved profile being configured to be oriented aft and whose center of curvature is forward relative to the fin of the first type,
fins of a second type, wherein a chord of the fins of the second type is smaller than a chord of the fins of the first type,
wherein the fins of the first type and the fins of the second type are disposed in an alternating arrangement along the grating, and
wherein each fin of the second type has a curved profile when viewed in a lateral direction relative to the grating, a rounding of the curved profile being configured to be oriented aft and whose center of curvature is forward relative to the fin of the second type.
2. The grating according to claim 1 , wherein the trailing edges of the fins of the first type and the trailing edges of the fins of the second type are in one and the same output plane.
3. The grating according to claim 2 , wherein the leading edges of the fins of the first type are in one and the same input plane parallel to the output plane, and wherein the leading edge of each fin of the second type is in an intermediate plane between the input plane and the output plane and at a distance from each of the input and output planes.
4. The grating according to claim 1 , wherein:
0.2
×
s
≤
s
′
≤
0.8
×
s
;
0.2
×
h
≤
h
′
≤
0.8
×
h
;
with
30
mm
≤
h
≤
70
mm
;
-
1.5
×
θ
1
≤
θ
1
′
≤
1.5
×
θ
1
;
with
-
10
°
≤
θ
1
≤
70
°
;
-
1.5
×
θ
2
≤
θ
2
′
≤
1.5
×
θ
2
;
with
0
°
≤
θ
2
≤
50
°
;
c
′
=
h
′
cos
(
st
′
)
with
0
°
≤
st
′
≤
θ
2
′
;
and
0.5
≤
c
s
≤
2
;
with
c
=
h
cos
(
st
)
and
0
°
≤
st
≤
θ
2
;
where “c” is the chord of the fins of the first type,
“c′” is the chord of the fins of the second type,
“s” is a distance between two consecutive fins of the first type,
“s′” is a distance between a fin of the first type and a consecutive fin of the second type,
“h” is a height of the fins of the first type,
“h′” is a height of the fins of the second type,
“θ 1 ” is an input angle between a tangent to a curvature of the leading edge of the fins of the first type and a vertical axis,
“θ 1 ′” is an input angle between s tangent to a curvature of the leading edge of the fins of the second type and the vertical axis,
“θ 2 ” is an output angle between a tangent to a curvature of the trailing edge of the fins of the first type and the vertical axis,
“θ 2 ′” is an output angle between a tangent to a curvature of the trailing edge of the fins of the second type and the vertical axis,
“st” is an offset angle of the fins of the first type, and
“st′” is an offset angle of the fins of the second type.
5. The grating according to claim 1 , wherein heights of the fins of the second type vary from one fin of the second type to another fin of the second type.
6. The grating according to claim 1 , wherein a distance between a fin of the first type and a consecutive fin of the second type in a forward to aft direction, is different from a distance between another fin of the first type and a consecutive fin of the second type in the forward to aft direction to this other fin of the first type.
7. The grating according to claim 1 , wherein input angles of the fins of the second type vary from one fin of the second type to another fin of the second type.
8. A turbofan engine comprising at least one grating for forming a reverse flow according to claim 1 .
9. An aircraft comprising at least one turbofan engine according to claim 8 .
10. A grating for forming a reverse flow of a turbofan engine having a forward longitudinal end and an aft longitudinal end and a lateral width, the grating comprising:
fins of a first type having a curved profile when viewed in a lateral direction relative to the grating, a rounding of the curved profile being configured to be oriented aft and whose center of curvature is forward relative to the fin of the first type,
fins of a second type, wherein a chord of the fins of the second type is smaller than a chord of the fins of the first type,
wherein the fins of the first type and the fins of the second type are disposed in an alternating arrangement along the grating.