Aircraft engine nacelle having a fan ramp with hinged flaps

Abstract

An engine nacelle (100) for an aircraft (10) has a fan housing; a wind shield that can be moved between an advanced position and a retracted position, the retracted position opening an opening between a bypass duct and the outside; a deflector fixed to the mobile wind shield, wherein in the advanced position the deflector surrounds the fan housing, and wherein in the retracted position the deflector spans the opening; and a fan ramp (120) having a mounting base (122) and flaps (124), the flaps being movable on the mounting base (122) between a stowed position and an extended position, wherein for each flap (124), the fan ramp (120) has a reset element (312) that urges the flap (124) into the extended position, and the deflector has a stop that contacts the flap (124) when the mobile wind shield passes from the retracted position into the advanced position. Thus, in the advanced position, the flaps are folded back and their volume is reduced.

Description

Technical Field

[0001] The invention relates to an aircraft nacelle having a fan ramp with hinged flaps, and to an aircraft having at least one such nacelle. Background Art

[0002] Figure 4 A nacelle 400 of a prior art aircraft is shown, in particular a nacelle for a turbofan engine 400. Such a nacelle 400 surrounds the engine by its engine case 402, and the nacelle 400 and the engine case 402 together define a bypass duct 404 in which an air flow 406 flows from front to rear.

[0003] The bypass duct 404 is located at the rear of the fan driving the air flow 406 and is located inside a fan casing 408 which has the general shape of a cylinder and is fastened to a fixed structure of the nacelle 400 .

[0004] The engine nacelle 400 also has a fixed wind shield 410 fixed to a fixed structure and a movable wind shield 412 installed to be able to move translationally on the fixed structure. The fixed wind shield 410 and the movable wind shield 412 are generally cylindrical. The fixed wind shield 410 surrounds the fan housing 408.

[0005] The mobile wind shield 412 is capable of moving between an advanced position and a retracted position, in which the mobile wind shield 412 is extended rearwardly relative to the fixed wind shield 410, and in the retracted position, the mobile wind shield 412 moves away from the fixed wind shield 410 to open an opening 414 therebetween, which establishes fluid communication between the bypass duct 404 and the outside of the engine nacelle 400.

[0006] The turbofan engine also has a plurality of reversing doors 416, each of which can be in a stowed position and an extended position ( Figure 4 ) moves between the bypass duct 404, thereby directing the air flow 406 to the opening 414 and thus ensuring the thrust reversal of the turbofan engine; in the stowed position, the reverse door does not block the bypass duct 404, and in the deployed position, the reverse door blocks the bypass duct 404.

[0007] To better direct the air flow 406 into the opening 414 and to the exterior, a flow director 418 is disposed across the opening 414 .

[0008] To direct the air flow 406 toward the deflector 418, the nacelle 400 has a fan ramp 420, which is an aerodynamic structure fastened to the fan housing 408 just upstream of the opening 414. The fan ramp 420 has a dome-shaped area 422 fastened to the rear of the fan housing 408 and oriented toward the opening 414, and a vertical area 424 fastened to the rear of the dome-shaped area 422 and oriented generally radially toward the front of the deflector 418.

[0009] Although this installation provides good results, the specific shape of the fan ramp 420, and in particular the presence of the vertical area 424, makes it necessary to increase the diameter of the engine nacelle 400 to surround the fan ramp 420, which may cause significant drag in flight. Summary of the invention

[0010] The object of the invention is to propose a nacelle having a fan ramp equipped with hinged flaps which are retracted when the rear cowl is pushed forward and which make it possible to reduce the thickness of the fairing layer.

[0011] To this end, an engine nacelle for an aircraft is proposed, the engine nacelle having:

[0012] - a fan casing defining a bypass duct,

[0013] - a fixed fan shield arranged around the fan housing,

[0014] a mobile wind shield capable of movement between an advanced position in which the mobile wind shield is extended rearwardly relative to the fixed wind shield and a retracted position in which the mobile wind shield is moved away from the fixed wind shield so as to open an opening therebetween, the opening establishing fluid communication between the bypass duct and the outside of the engine nacelle,

[0015] a deflector fixed to the mobile fan shield, wherein, in the advanced position, the deflector surrounds the fan housing, and wherein, in the retracted position, the deflector is arranged across the opening, and

[0016] - a fan ramp having a mounting base and flaps, wherein the mounting base is in the form of a ring fastened to the rear of the fan housing, and wherein each flap has a downstream edge and an upstream edge opposite the downstream edge and is rotatable on the mounting base between a stowed position, in which the upstream edge then projects toward the front of the nacelle, and a deployed position, in which the upstream edge then projects through the opening toward the outside of the nacelle and upstream of the deflector in the retracted position.

[0017] wherein, for each flap, the fan ramp has a return element urging the flap into the deployed position, and wherein, for each flap, the deflector has a stopper contacting the rear of the flap when the mobile wind shield passes from the retracted position into the advanced position.

[0018] Thus, in the forward position, the flaps are folded back and their volume is reduced.

[0019] Advantageously, each flap is fastened to the mounting base by means of two hinges.

[0020] Advantageously, each hinge consists of a U-shaped clip fixed to the flap, a tang fixed to the mounting base and a pin passing through said U-shaped clip and said tang.

[0021] Advantageously, each return element is a torsion spring mounted to the pin, one end of which is urged against the flap and the other end of which is urged against the mounting base.

[0022] The invention also proposes an aircraft having an engine and a nacelle according to one of the aforementioned variants, wherein the engine is surrounded by the nacelle. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other features of the present invention will become more apparent upon reading the following description of exemplary embodiments given with reference to the accompanying drawings, in which:

[0024] Figure 1 is a side view of an aircraft having an engine nacelle of the present invention,

[0025] Figure 2 is a schematic cross-sectional view through an axial plane of an engine nacelle of the present invention,

[0026] Figure 3 is a three-dimensional diagram of the fan bevel of the present invention, and

[0027] Figure 4 is a schematic cross-sectional view through an axial plane of a prior art engine nacelle. DETAILED DESCRIPTION

[0028] Figure 1 An aircraft 10 is shown having an engine nacelle 100 supported by a pylon 16 secured beneath a wing 14 .

[0029] In the following description, position-related terms are given with reference to the aircraft being in a forward motion position, i.e. Figure 1 , wherein arrow F shows the direction of forward movement of the aircraft 10 .

[0030] In the following description, and by convention, X designates the longitudinal axis of the nacelle 100, which is parallel to the longitudinal axis of the aircraft 10 and is in the direction of forward motion of the aircraft 10; Y designates the lateral axis of the nacelle 100, which is horizontal when the aircraft 10 is on the ground; and Z designates the vertical axis or the vertical height when the aircraft 10 is on the ground; these three directions X, Y and Z are orthogonal to each other.

[0031] Figure 2 An axial cross section of an engine nacelle 100 of the present invention is shown, which is similar to the engine nacelle 400 of the prior art, except for the fan slope.

[0032] The nacelle 100 is implemented in the context of a turbofan engine and surrounds the engine, here illustrated by its engine case 102 .

[0033] The turbofan engine has a fan that drives the air flow from front to rear and is surrounded by a fan housing 108 that is fastened to a fixed structure of the nacelle 100 surrounding the engine case 102 .

[0034] The blower housing 108 and the engine housing 102 define a bypass duct 104 therebetween, in which an air flow 106 flows.

[0035] The nacelle 100 also has a fixed wind shield 110 fixed to a fixed structure and a mobile wind shield 112 mounted so as to be able to translate on the fixed structure. In the embodiment of the invention shown here, the fixed wind shield 110 surrounds the fan housing 108.

[0036] The bypass duct 104 extends at the rear of the fan housing 108 between the fan housings 110 and 112 and the engine housing 102.

[0037] The mobile air shield 112 is movable between an advanced position, in which the mobile air shield 110 is extended rearwardly relative to the fixed air shield 112, and a retracted position, in which the mobile air shield 110 is moved rearwardly away from the fixed air shield 110, thereby opening an opening 114 therebetween, which establishes fluid communication between the bypass duct 104 and the outside of the engine nacelle 100. As in the prior art, the mobile air shield 112 is made to move by any suitable means known to those skilled in the art, such as, for example, a slide, an actuator, a motor, etc.

[0038] The turbofan engine also has a plurality of reversing doors 116, each of which can be in a stowed position and an extended position ( Figure 2), in the stowed position, the reversing door does not block the bypass duct 104, and in the deployed position, the reversing door blocks the bypass duct 104, thereby directing the air flow 106 toward the opening 114 and then toward the outside, thus ensuring the thrust reversal of the turbofan engine. As in the prior art, the reversing door 116 is made to move by any suitable means known to those skilled in the art, such as, for example, a slide, an actuator, a motor, etc.

[0039] The nacelle 100 has a guide 118 (also called a “cascade”) that can be translated together with the mobile wind shield 112, wherein, in the advanced position, the guide 118 is positioned around the fan housing 108, located between the fan housing 108 and the fixed wind shield 108, and wherein, in the retracted position, the guide 118 is arranged across the opening 114, so as to better guide the air flow 106 into the opening 114 and toward the outside.

[0040] To direct the air 106 toward the opening 114 and the air guide 118 , the nacelle 100 has a fan ramp 120 having a mounting base 122 and flaps 124 and arranged just upstream of the opening 114 and just upstream of the air guide 118 when they are in the retracted position.

[0041] The mounting base 122 is in the form of a ring fastened to the rear of the fan housing 108 and in this case has a dome shape oriented towards the opening 114 and the bypass duct 104. This mounting base 122 makes it possible to widen the bypass duct 104 towards the opening 114. Of course, the mounting base 122 can be an integral part of the fan housing 108.

[0042] like Figure 3 As shown, the plurality of flaps 124 are mounted so as to be rotatable on the mounting base 122 about a rotation axis 302 that is substantially tangential to the mounting base 122 .

[0043] In this case, each flap 124 is mounted so as to be hinged on the mounting base 122 via two hinge portions 304 .

[0044] The flaps 124 are arranged one after another around the mounting base 122 , and the number of flaps 124 and the angular extent of each flap 124 depend primarily on the diameter of the mounting base 122 .

[0045] Each flap 124 has a downstream edge 306 that is rotatable on the mounting base 122 , and an upstream edge 308 , which is the edge opposite the downstream edge 306 and is therefore the free edge of the flap 124 .

[0046] Each flap 124 is movable between a stowed position and a deployed position.

[0047] In the stowed position, the flaps 124 are folded downwardly toward the mounting base 122, in this case, toward the outer surface of the mounting base 122. Figure 2 Then, the upstream edge 308 projects toward the front of the engine nacelle 100. The stowed position allows the guide 118 to bypass the flap 124.

[0048] In the deployed position, the flap 124 is generally oriented in a plane perpendicular to the longitudinal axis X and is therefore lifted off the mounting base 122. Figure 2 Then, the upstream edge 308 protrudes toward the outside of the nacelle 100 through the opening 114, and the flap 124 then replaces the vertical area 424 of the prior art (assuming the position of the vertical area 424 of the prior art). By rotating the flap 124 toward the front of the nacelle 100, the passage from the deployed position to the stowed position is achieved.

[0049] For each flap 142 , the fan ramp 120 also has a return element 312 which urges the flap 124 into the deployed position.

[0050] For each flap 124 , when the mobile wind shield 112 is turned from the retracted position to the advanced position, the deflector 118 has a stop 130 that contacts the rear of each flap 124 and pushes each of them back toward its stowed position.

[0051] Thus, by placing the retractable flaps 124 in place, the diameter of the nacelle 100 , ie the diameter of the fixed cowl 110 and the movable cowl 112 , is reduced, while reducing the thickness of the streamlined layer, while maintaining the guidance of the air flow 104 towards the outside in the retracted position.

[0052] In this case, each hinge 304 is comprised of a clevis secured to the flap 124 , a tang secured to the mounting base 122 , and a pin passing through the clevis and the tang.

[0053] Each return element 312 is, for example, a torsion spring fitted to a pin, one end of the return element being urged against the flap 124 and the other end being urged against the mounting base 122. In this case, there is one return element 312 per hinge 304.

Claims

1. An engine nacelle (100) for an aircraft (10), the engine nacelle (100) comprising: - a fan housing (108) defining a bypass duct (104), - a fixed fan shield (110) arranged around the fan housing (108), a mobile air shield (112) movable between an advanced position in which the mobile air shield (112) is extended rearwardly relative to the fixed air shield (110) and a retracted position in which the mobile air shield (112) is moved away from the fixed air shield (110) so as to open an opening (114) therebetween, the opening establishing fluid communication between the bypass duct (104) and the outside of the nacelle (100), - a flow guide (118) fixed to the mobile wind shield (112), wherein: In the advanced position, the guide (118) surrounds the blower housing (108), and wherein in the retracted position, the guide (118) is disposed across the opening (114), and - a fan ramp (120) having a mounting base (122) and flaps (124), wherein the mounting base (122) is in the form of a ring fastened to the rear of the fan housing (108), and wherein each flap (124) has a downstream edge (306) and an upstream edge (308) opposite the downstream edge (306), wherein each flap (124) is rotatable on the mounting base (122) between a stowed position in which the upstream edge (308) subsequently projects toward the front of the nacelle (100) and a deployed position in which the upstream edge (308) subsequently projects through the opening (114) toward the outside of the nacelle (100) and upstream of the guide (118) in the retracted position, wherein, for each flap (124), the fan ramp (120) has a reset element (312) for urging the flap (124) into the deployed position, and wherein, for each flap (124), the guide (118) has a stopper (130) for contacting the rear of the flap (124) when the mobile wind shield (112) passes from the retracted position to the advanced position.

2. The engine nacelle (100) according to claim 1, characterized in that: Each of the flaps (124) is fastened to the mounting base (122) via two hinges (304).

3. The engine nacelle (100) according to claim 2, characterized in that: Each of the hinges (304) is composed of a U-shaped clip fixed to the flap (124), a tang fixed to the mounting base (122), and a pin passing through the U-shaped clip and the tang.

4. The engine nacelle (100) according to claim 3, characterized in that: Each of the return elements (312) is a torsion spring fitted to the pin, one end of the return element being urged against the flap (124) and the other end of the return element being urged against the mounting base (122).

5. An aircraft (10) having an engine (102) and an engine nacelle (100) according to claim 1, wherein: The engine (102) is surrounded by the nacelle (100).

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