Aircraft equipped with an exhaust duct coupled to a stabilization system

Abstract

The present invention relates to an aircraft (1) equipped with at least one exhaust duct (30) for ejecting gases from an engine (10), the exhaust duct (30) being partially housed in an internal housing (25) of the aircraft (1), the housing (25) being separated from an external environment (EXT) located outside the aircraft (1) by at least one cowling (35) movable relative to a supporting structure (3) of the aircraft (1), the exhaust duct (30) comprising an ejection section (32) passing through a passage (40) of the cowling (35) without touching the cowling (35), a space (41) separating the ejection section (32) from the cowling (35). The aircraft (1) comprises at least one stabilization system (50) coupled to the exhaust duct (30), the stabilization system (50) comprising a stiffening ring (55) attached to the exhaust duct (30) and at least one fastener (60) connecting the exhaust duct (30) to the cowling (35). Abbreviated figure: Figure 1

Description

Title of the invention: Aircraft equipped with an exhaust duct coupled to a stabilization system

[0001] The present invention relates to an aircraft having an exhaust duct coupled to a stabilization system which is configured to stabilize the exhaust duct.

[0002] An aircraft, and for example a rotorcraft, may comprise an engine which expels combustion gases through an exhaust nozzle.

[0003] The engine is usually housed in a compartment of the aircraft called the "engine compartment". The engine compartment may be delimited by one or more firewalls and / or at least one hood.

[0004] The aircraft may then comprise an exhaust duct which is open to the engine compartment and to an environment external to the aircraft. The exhaust duct may be fixed and arranged in a housing delimited by a movable cowl, or even a firewall for example. This exhaust duct locally surrounds the exhaust nozzle. This exhaust duct may allow the combustion gases from the exhaust nozzle of an engine to be mixed with fresh air from the engine compartment and / or the gases to be directed towards preferential zones. The exhaust nozzle may be described as a primary or main nozzle, the exhaust duct being able to be described as a secondary nozzle.

[0005] Furthermore, the development of an exhaust duct is complex due in particular to the high temperature of the ejected gases, of the order of several hundred degrees Celsius, the pressure exerted by these gases on the exhaust duct as well as the vibration phenomena.

[0006] For example, the rotation of a main rotor of a helicopter, the operation of an engine and a structure supporting the exhaust duct are sources of vibrations likely to excite an exhaust duct. The movement of air near the exhaust duct is also a source of vibrations for this exhaust duct.

[0007] Therefore, an exhaust duct is likely to deform in flight due to these various constraints, in particular due to thermal constraints as well as its vibratory and dynamic behavior and the setting of its natural frequency with respect to the frequencies of the excitations undergone.

[0008] Modifying the exhaust duct to limit these deformations can be relatively tricky, in terms of financial cost, time, and even mass. In addition, modifying an exhaust duct can have an impact on its environment. operation, and for example on the supporting structure which must carry the exhaust duct.

[0009] Document EP3575219 describes a rotorcraft having at least one engine associated with an exhaust duct. The exhaust duct is attached to a fixed structure of the rotorcraft by a mechanism to be stabilized statically as well as following thermal expansion.

[0010] Document EP2894099 describes a method of manufacturing an exhaust duct provided with fixing rings.

[0011] The present invention therefore aims to propose an aircraft equipped with an exhaust duct cooperating with an innovative stabilization system.

[0012] The invention relates to an aircraft provided with at least one exhaust duct for ejecting gases from an engine, the exhaust duct being partially housed in an internal housing of the aircraft, the housing being separated from an external environment located outside the aircraft by at least one cowl, this cowl being movable relative to a supporting structure of the aircraft, the exhaust duct comprising an ejector section passing through a passage of the cowl without touching the cowl, a space separating the ejector section from the cowl.

[0013] This aircraft comprises at least one stabilization system coupled to the exhaust duct, the stabilization system comprising a stiffening ring secured to the exhaust duct and at least one attachment connecting the exhaust duct to the cowl.

[0014] Thus, the stabilization system comprises two dissimilar devices which operate in synergy to improve, in use, the behavior of the exhaust duct with regard to the stresses undergone.

[0015] A stiffening ring is positioned around the exhaust duct, and against this exhaust duct. In particular, the stiffening ring makes it possible to modify the natural frequency of the exhaust duct to move it away from an excitation frequency. The stiffening ring also makes it possible to locally constrain the exhaust duct to prevent its deformation, for example by avoiding ovalization of the exhaust duct. This stiffening ring can be arranged so as to have an acceptable impact on the aerodynamics of the aircraft, or even on the ventilation of the housing.

[0016] The fastener(s) make it possible to fix the exhaust duct to the cowl in order to stabilize this exhaust duct in flight. The fastener(s) may be defined so as not to hinder the thermal expansion of the exhaust duct in operation while constraining its movement in the reference frame of the aircraft. The fastener(s) may further be defined to allow rapid detachment of the exhaust duct and the cowl, and thus to allow the cowl to be opened.

[0017] This stabilization system can have a low mass impact, has no impact on the environment of the exhaust duct with the exception of the cowling and can be installed on an existing aircraft during a so-called "retrofit" campaign in English.

[0018] The aircraft may further comprise one or more of the following characteristics, taken alone or in combination.

[0019] Thus, the stiffening ring can surround the exhaust duct.

[0020] The stiffening ring may surround a section of the exhaust duct, namely completely and therefore 360 ​​degrees around an internal volume of the exhaust duct.

[0021] Alternatively, the stiffening ring may extend over an angle of less than 360 degrees from a geometric axis, and therefore from the internal volume. The stiffening ring then only partially surrounds the exhaust duct.

[0022] According to a possibility compatible with the previous ones, the stiffening ring can be arranged around the ejector section.

[0023] The stiffening ring generates pressure on the exhaust duct when this exhaust duct expands under the effect of the temperature of the gases. The pressure generated by the stiffening ring on the exhaust duct can be optimized when the stiffening ring is arranged on the ejector section which is likely to undergo less thermal expansion than an inlet section of the exhaust duct for example. In addition, the stiffening ring tends to stiffen the ejector section which is likely to deform within a conventional exhaust duct.

[0024] According to a possibility compatible with the previous ones, the stiffening ring can be arranged at least partially in the external environment.

[0025] The impact on the aerodynamics of the aircraft is thus limited. The stiffening ring remains arranged as close as possible, or even on the section of the exhaust duct which is likely to deform within a conventional exhaust duct.

[0026] Alternatively and depending on requirements, the stiffening ring can be arranged entirely in the external environment.

[0027] According to a possibility compatible with the previous ones, the stiffening ring may comprise an L-shaped, T-shaped, C-shaped or omega-shaped profile. The omega-shaped shape may comprise a substantially flat branch, followed by a substantially rounded or non-rounded C-shaped shape tilted 90 degrees to the right, then another substantially flat branch.

[0028] Such a profile may be sufficient to adequately modify the behavior of the exhaust duct.

[0029] According to a possibility compatible with the previous ones, the stiffening ring can be fixed to the exhaust duct by detachable stiffening fasteners.

[0030] The term “dissociable” refers to fasteners that can be removed without damaging the stiffening ring and / or the exhaust duct during a maintenance campaign.

[0031] For example, the stiffening fasteners include rivets or the like.

[0032] According to a possibility compatible with the previous ones, said at least one attachment may comprise a first support secured to the exhaust duct and a second support secured to the hood, said at least one attachment comprising a connecting clip fixing the first support to the second support.

[0033] The connecting fastener may be a so-called quick fastener. According to examples given for illustration purposes, the connecting fastener may comprise a quarter-turn fastener or even a fastener known under the brand name dzus® for example. An operator can then easily separate the exhaust duct and the hood.

[0034] According to a possibility compatible with the previous ones, said at least one fixing can be arranged at least partially in said housing.

[0035] The fastener may be entirely housed within the housing or may extend outside the housing. For example, the aforementioned fastener may be located in the external environment.

[0036] According to a possibility compatible with the previous ones, said at least one fixing can be accessible via said space separating the ejector section from the hood.

[0037] The space may have dimensions greater than the dimensions of a human hand or a tool capable of opening the fastener.

[0038] For illustration purposes, the space may have a dimension at least greater than 5 centimeters.

[0039] The arrangement of the exhaust duct in a passage of the hood having larger dimensions makes it possible to provide a space which can be crossed by a tool and / or a hand. An operator can introduce a hand into the space to detach the exhaust duct from the hood, in order to open the hood for example.

[0040] According to a possibility compatible with the previous ones, said at least one fixing can be adjacent to the stiffening ring.

[0041] The fixing(s) are as close as possible to the stiffening ring to provide fixing points and stiffness substantially in the same location.

[0042] Optionally, at least one fastener may be attached to the stiffening ring.

[0043] The attachment thus connects the exhaust duct to the hood via the stiffening ring.

[0044] Alternatively, the attachment may be attached directly to the exhaust duct.

[0045] According to a possibility compatible with the previous ones, said at least one fixing may comprise several fixings arranged around the exhaust duct.

[0046] The fasteners are then distributed, in an iso-distributed or non-iso-distributed manner, around the exhaust duct to stabilize the exhaust duct in several zones and along several geometric axes.

[0047] The invention and its advantages will appear in more detail in the context of the description which follows with examples given for illustrative purposes with reference to the appended figures which represent:

[0048] [Fig.l], a couple diagram illustrating an aircraft according to the invention,

[0049] [Fig.2], a sectional diagram illustrating an aircraft according to the invention, and

[0050] [Fig.3], a view partially showing an aircraft according to the invention.

[0051] Elements present in several distinct figures are assigned a single reference.

[0052] [Fig.l] shows an aircraft 1 according to the invention.

[0053] Such an aircraft 1 comprises a supporting structure 3 carrying at least one engine 10. The engine 10 is in particular arranged in an engine compartment 5.

[0054] The engine compartment 5 is delimited by at least one wall 6, 7, 8 and 9. The wall(s) 6, 7, 8 and 9 may be fire-resistant walls, for example fireproof. For example, the engine compartment 5 is delimited along a longitudinal axis by at least one longitudinal wall 6, 8. For example, the engine compartment 5 is delimited along a transverse axis by at least one transverse wall 7 and a cowling, and vertically at least by a bottom wall 9.

[0055] The engine(s) 10 may be thermal engines capable of burning fuel to drive each power shaft. According to one possibility, the engine(s) 10 may be turboshaft engines. Alternatively, the engine(s) 10 may be piston engines for example.

[0056] Regardless of the nature of the engine(s) 10 and their arrangement, each engine 10 comprises an ejection nozzle 20 for at least ejecting, along the arrow F1, gases resulting from the combustion of the fuel in the engine 10 in question. For example, the ejection nozzle 20 passes through a longitudinal wall 6.

[0057] Therefore, an exhaust duct 30 according to the invention at least partially surrounds the ejection nozzle 20, namely the entire ejection nozzle 20 or a section of the ejection nozzle 20 and for example at least one ejection portion of the ejection nozzle 20 through which gases are expelled. For example, the exhaust duct 30 surrounds at least a portion of the ejection nozzle 20 located outside the engine compartment 5.

[0058] The exhaust duct 30 may comprise a peripheral wall. The peripheral wall delimits an internal volume located inside the exhaust duct 30 and accommodating at least one section of the ejection nozzle 20.

[0059] Furthermore, the exhaust duct 30 extends from an inlet section 301, possibly opening onto the engine compartment 5, to an outlet section 302, possibly opening onto an environment EXT located outside the aircraft 1. Therefore, air present in the compartment 5 can be sucked into the duct exhaust 30, then is expelled outside the vehicle with gases from the exhaust nozzle 20 through the outlet section 302.

[0060] In particular, the exhaust duct may comprise an inlet section 31 comprising the inlet section 301, then an ejector section 32 comprising the outlet section 302.

[0061] Furthermore, the exhaust duct 30 is partially housed in an internal housing 25 of the aircraft 1.

[0062] This housing 25 is in particular separated from the external environment EXT at least by a cover 35. The cover 35 is movable relative to the supporting structure 3 of the aircraft 1. For this purpose, the cover 35 can be connected to the supporting structure 3 by at least one mobility system 38, 39 illustrated schematically. Such a mobility system 38, 39 can comprise at least one rail, at least one slider, at least one hinge for example.

[0063] The hood 35 may comprise a cowling panel 36. The hood 35 may comprise a protective casing 37 secured to the cowling panel 36 as illustrated in [Fig.2] described below.

[0064] Independently of the components of the cover 35 and the mobility systems 38, 39 making it movable relative to the supporting structure 3, the cover 35 comprises a passage 40. Such a passage 40 may comprise a cutout made in the cover panel 36, and where appropriate not blocked by the protective casing 37.

[0065] Therefore, the ejector section 32 of the exhaust duct 30 passes through the passage 40 of the cover 35 without touching this cover 35. A space 41 therefore separates the ejector section 32 from the cover 35. This space 41 is an annular space which surrounds the exhaust duct by separating it from an edge delimiting the passage 40.

[0066] According to another aspect, the aircraft 1 comprises at least one stabilization system 50 coupled to an exhaust duct 30. In the presence of several engines 10 and several respective exhaust ducts 30, each exhaust duct 30 is coupled to its own stabilization system 50.

[0067] Regardless of the number of stabilization systems 50, such a stabilization system 50 makes it possible to modify the dynamic and vibratory behavior of the exhaust duct 30, without stress on the supporting structure 3 or the engine compartment 5 for example.

[0068] Such a stabilization system 50 comprises a stiffening ring 55 which is attached to the exhaust duct 30. The stiffening ring can completely surround the exhaust duct, namely 360 degrees around a geometric axis, or can partially surround the exhaust duct.

[0069] This stiffening ring 55 is thus made integral with the exhaust duct 30.

[0070] For example, the stiffening ring 55 is arranged against the ejector section 32.

[0071] Optionally, the stiffening ring 55 may be arranged at least partially in the external environment EXT.

[0072] According to a variant, the stiffening ring 55 and the exhaust duct 30 form a single piece, the stiffening ring 55 and the exhaust duct 30 being inseparable without breakage. For example, the stiffening ring 55 is welded to the exhaust duct 30.

[0073] According to another variant, the stiffening ring 55 is fixed to the exhaust duct 30 by detachable stiffening fasteners 56. According to an illustration of this possibility, the stiffening fasteners 56 comprise rivets.

[0074] According to another characteristic, the stiffening ring 55 may have an L-shaped, T-shaped, C-shaped or omega-shaped profile. Such a stiffening ring 55 makes it possible to modify the natural frequency of the exhaust duct 30 relatively easily and at low cost.

[0075] Regardless of the way in which the stiffening ring 55 is produced, the stabilization system 50 also comprises one or more fasteners 60 connecting the exhaust duct 30 to the cover 35. At least one fastener 60 may in particular be fixed to the ejector section 32. According to the examples illustrated, the stabilization system 50 comprises several fasteners 60 arranged around the exhaust duct 30.

[0076] According to the example of [Fig.l], at least one fastener 60 can in particular be fixed to the cover panel 36 of the cover 35.

[0077] In a complementary or alternative manner and with reference to [Fig.2], at least one fixing 60 can in particular be fixed to the protective casing 37 of the cover 35.

[0078] Regardless of the member of the cover 35 fixed to a fixing 60, at least one fixing 60 is possibly positioned so as to be adjacent to the stiffening ring 55.

[0079] Optionally, at least one fastener 60 may be attached to the stiffening ring 55.

[0080] Whatever the positioning of a fixing 60, this fixing 60 may comprise a first support 61 and a second support 62 assembled to each other by a connecting fastener 63.

[0081] For example, the first support 61 is integral with the exhaust duct 30, directly or via the stiffening ring 55. The first support 61 can be fixed to the exhaust duct 30 or to the stiffening ring 55 by screwing, riveting, gluing, welding, etc.

[0082] For example, the second support 62 is integral with the cover 35. The second support 62 can be fixed to the cover 35 by screwing, riveting, gluing, welding, etc.

[0083] Furthermore, the first support 61 may comprise a male or female yoke comprising at least one first orifice. Similarly, the second support 62 may comprise a male or female yoke comprising at least one second orifice. The connecting fastener 63 then comprises in particular a connection passing through the first orifice(s) and the second orifice(s).

[0084] According to another aspect, a fastener 60 may be located at least partially in the housing 25. For example, the first support 61 of a fastener 60 may extend partly into the external environment EXT, and the second support 62 may be located in the housing 25. According to another aerodynamically optimized alternative, the entire fastener 60 is arranged in the housing 25. Alternatively, at least one fastener 60 may be entirely in the external environment EXT.

[0085] Optionally, at least one fastener 60 is accessible to an operator via the space 41.

[0086] In this context, [Fig. 3] illustrates an exemplary embodiment comprising several fasteners 60. The cover 35 is made locally transparent to allow the fasteners 60 to be viewed.

[0087] Each fastener 60 comprises a first support 61, a second support 62 and a connecting clip 63. Furthermore, each fastener 60, and in particular its connecting clip 63, is accessible to an operator via the space 41.

[0088] Naturally, the present invention is subject to numerous variations as to its implementation. Although several embodiments have been described, it is understood that it is not conceivable to exhaustively identify all possible modes. It is of course conceivable to replace a means described by an equivalent means without departing from the scope of the present invention and the claims.

Claims

Claims

1. Aircraft (1) provided with at least one exhaust duct (30) for ejecting gases from an engine (10), the exhaust duct (30) being partially housed in an internal housing (25) of the aircraft (1), the housing (25) being separated from an external environment (EXT) located outside the aircraft (1) by at least one cowl (35), the cowl (35) being movable relative to a supporting structure (3) of the aircraft (1), the exhaust duct (30) comprising an ejector section (32) passing through a passage (40) of the cowl (35) without touching the cowl (35), a space (41) separating the ejector section (32) from the cowl (35), characterized in that the aircraft (1) comprises at least one stabilization system (50) coupled to the exhaust duct (30), the stabilization system (50) comprising a stiffening ring (55) secured to the exhaust duct (30) and at least one fastener (60) connecting the exhaust duct (30) to the hood (35).

2. Aircraft according to claim 1, characterized in that said stiffening ring (55) surrounds the exhaust duct (30).

3. Aircraft according to claim 1, characterized in that said stiffening ring (55) extends over an angle of less than 360 degrees around a geometric axis.

4. Aircraft according to any one of claims 1 to 3, characterized in that said stiffening ring (55) is arranged around the ejector section (32).

5. Aircraft according to any one of claims 1 to 4, characterized in that said stiffening ring (55) is arranged at least partially in the external environment (EXT).

6. Aircraft according to any one of claims 1 to 5, characterized in that said stiffening ring (55) has an L-shaped, T-shaped, C-shaped or omega-shaped profile.

7. Aircraft according to any one of claims 1 to 6, characterized in that said stiffening ring (55) is fixed to the exhaust duct (30) by detachable stiffening fasteners (56).

8. Aircraft according to any one of claims 1 to 7, characterized in that said at least one attachment (60) comprises a first support (61) secured to the exhaust duct (30) and a second support (62) secured to the cowl (35), said at least one attachment (60) comprising a connecting clip (63) fixing the first support (61) to the second support (62).

9. Aircraft according to any one of claims 1 to 8, characterized in that said at least one fixing (60) is arranged at least partially in said housing (25).

10. Aircraft according to any one of claims 1 to 9, characterized in that said at least one fixing (60) is accessible via said space (41) separating the ejector section from the cowling.

11. Aircraft according to any one of claims 1 to 10, characterized in that said at least one fixing (60) is adjacent to the stiffening ring (55).

12. Aircraft according to any one of claims 1 to 11, characterized in that said attachment (60) is attached to the stiffening ring (55).

13. Aircraft according to any one of claims 1 to 12, characterized in that said at least one fixing (60) comprises several fixings (60) arranged around the exhaust duct (30).

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