阅读说明：本技术 用于航空器的推进系统
(Propulsion system for aircraft
) 是由 让-路易斯·罗伯特·盖伊·贝斯
叶-邦纳·卡琳娜·马尔多纳多 于 2020-04-10 设计创作，主要内容包括：本发明涉及一种用于航空器的推进系统和航空器。推进系统包括至少一个转子和发动机舱整流罩,所述发动机舱整流罩围绕所述至少一个转子相对于所述转子的旋转轴线延伸,所述发动机舱整流罩包括：前段,其形成所述发动机舱整流罩的入口截面；后段,其末端形成所述发动机舱整流罩的出口截面；以及中间段,其连接所述前段和所述后段；其特征在于,所述后段包括径向内壁和径向外壁,所述径向内壁和所述径向外壁是由可变形的形状记忆材料制成的,并且在于,所述航空推进系统包括至少一个千斤顶的至少一个驱动机构,所述千斤顶被配置为与嵌入在所述径向外壁的内表面中的装置配合以使所述出口截面的外直径在最小直径和最大直径之间变化。(The invention relates to a propulsion system for an aircraft and to an aircraft. The propulsion system includes at least one rotor and a nacelle fairing extending around an axis of rotation of the at least one rotor relative to the rotor, the nacelle fairing including: a forward section forming an inlet cross section of the nacelle fairing; a rear section, the end of which forms an outlet cross section of the nacelle fairing; and a middle section connecting the front section and the rear section; characterized in that said rear section comprises a radially inner wall and a radially outer wall, said radially inner wall and said radially outer wall being made of deformable shape memory material, and in that said aeronautical propulsion system comprises at least one drive mechanism of at least one jack configured to cooperate with means embedded in the inner surface of said radially outer wall to vary the outer diameter of said outlet section between a minimum diameter and a maximum diameter.)
1. A propulsion system (1, 1') for an aircraft comprising at least one rotor (2) and a nacelle fairing (3), said nacelle fairing (3) extending around a rotation axis (X) of said at least one rotor (2) with respect to said rotor (2), said nacelle fairing (3) comprising:
-a front section (10) forming an inlet section (BA) of the nacelle fairing (3);
-a rear section (20) whose end (21) forms an outlet section (BF) of the nacelle fairing (3); and
-a middle section (30) connecting the front section (10) and the rear section (20);
characterized in that said rear section (20) comprises a radially inner wall (20a) and a radially outer wall (20b), said radially inner wall (20a) and said radially outer wall (20b) being made of a deformable shape-memory material, and in that said aeronautical propulsion system (1, 1') comprises at least one drive mechanism of at least one jack (23), said jack (23) being configured to cooperate with means (24, 24') embedded in an inner surface (20b ') of said radially outer wall (20b) to bring about an outer diameter (D) of said outlet section (BF)BF) At the determined minimum diameter (D)BFc) And maximum diameter (D)BFd) To change between.
2. Propulsion system (1, 1') according to claim 1, wherein the means (24, 24') embedded in the inner surface of the radially outer wall (20b) comprise a plurality of prisms distributed in at least one annular row, driven by the at least one jack (23) through at least one annular element (25, 26).
3. Propulsion system (1, 1') according to any of the previous claims, further comprising a reinforcing cage (22), said reinforcing cage (22) connecting said radially inner wall (20a) and said radially outer wall (20b) of said rear section (20).
4. Propulsion system (1, 1') according to any of the previous claims, wherein the intermediate section (30) is rigid and connected to the engine (6) of the propulsion system (1, 1') by at least one arm (31).
5. Propulsion system (1, 1') according to any of the previous claims, wherein the front section (10) is made of deformable shape memory material, the front section (10) comprising an outer diameter (D) such that the inlet section (BA)BA) A variant arrangement.
6. Propulsion system (1, 1') according to the preceding claim, wherein the outer diameter (D) of the inlet section (BA)BA) Under the action of a pneumatic or hydraulic expansion device.
7. Propulsion system (1, 1') according to claim 5, wherein the outer diameter (D) of the inlet section (BA)BA) The front section (10) also has heat-shrink characteristics, varying under the action of an annular heat lining (13).
8. Propulsion system (1, 1') according to claim 5, wherein the outer diameter (D) of the inlet section (BA)BA) Is varied by the action of a jack-driving mechanism (230), said jack-driving mechanism (230) being configured to cooperate with means (240) fixed on an inner surface (12b') of a radially outer wall (12b) of said front section (10).
9. Propulsion system (1, 1') according to claim 5, wherein the outer diameter (D) of the inlet section (BA)BA) Is varied by a pneumatic or hydraulic annular actuator (40), said pneumatic or hydraulic annular actuator (40) being configured to deform radially under a predetermined operating pressure.
10. Propulsion system (1, 1') according to any of the previous claims, wherein the front section (10) comprises a plurality of stiffeners (14) connected by a buckling-resistant device (15).
11. An aircraft, characterized in that it comprises at least one propulsion system (1, 1') according to any one of claims 1 to 9, said propulsion system (1, 1') being pivotally mounted on the aircraft by means of a pivot axis (4, 4'), said pivot axis (4, 4') being eccentric or through-disposed with respect to the rotor (2).
Technical Field
The present invention relates to the field of aircraft propulsion systems. In particular, the present invention relates to a propulsion system employing a variable section nacelle fairing.
Background
In particular, the background art comprises the document WO-A1-2008/045081.
An aircraft propulsion system includes at least one rotor or propeller comprising a plurality of blades mounted on a rotating shaft.
Aircraft, particularly Vertical Take-Off and landing aircraft (ADAV or VTOL in english), are simple rotor propulsion systems when only a single rotor is included, or counter-rotor propulsion systems when a pair of counter-rotating rotors is included.
These propulsion systems employ a streamlined rotor (which is then surrounded by an annular nacelle fairing) or a free rotor on which the propulsion system, in particular the rotor (free or streamlined rotor) can be mounted, which enables the propulsion system and the rotor to be oriented between a vertical position and a horizontal position, for example in the vertical direction for vertical take-off and landing, and in the horizontal direction for forward flight or for flight mode.
Streamlined rotors have several advantages, such as:
the acoustic signature directly emitted by the rotor is greatly reduced;
-protecting the blades of the rotor from interference by surrounding obstacles;
improving the performance of the rotor, in particular for hovering or low-speed advancing aircraft.
In fact, at low speeds of forward travel or take-off associated with the action of the streamlined nacelle on the airflow in front of the rotor, the streamlined nacelle provides the rotor with additional hovering thrust (i.e. the aircraft is stationary in the air, maintaining lift without support or support), referred to as airflow duct (tube) with reference to the direction of flow of the airflow over the streamlined nacelle. More specifically, when there is no fairing, the airflow behind the rotor is naturally constricted inwardly by the free rotor. In other words, the diameter of the gas flow tube decreases gradually in the backward direction until the diameter is equal to half the cross section of the rotor.
In contrast, for a streamlined rotor, the outlet cross-section of the nacelle fairing defines the shape of the airflow duct, i.e. cylindrical at the outlet of the nacelle fairing, which has a substantially constant cross-section, thus hindering the natural contraction of the airflow.
The propulsion depends on the outlet cross section of the nacelle fairing, so that the larger the outlet cross section of the nacelle fairing, the greater the propulsion. In fact, the local pressure caused by the deformation of the nacelle fairing caused by the flowing air flow, the thrust increased by the presence of the nacelle fairing, is generated at the leading edge of the nacelle fairing. The greater the air flow permitted in the propulsion system, i.e. the greater the outlet section of the nacelle fairing, the greater this pressure and therefore the greater the thrust produced.
However, the faster the speed, the less efficient the propulsion of the rotor. In fact, as the forward speed of the aircraft increases, the faster the frontal drag due to the presence of the nacelle fairing increases, the lower the performance of the streamlined rotor. Thereby, the propulsive efficiency is reduced according to the rotation state and size of the rotor.
Thus, by employing a streamlined rotor, noise shielding and rotor perimeter safety are achieved by sacrificing propulsion efficiency while the aircraft is cruising (i.e., traveling at high speed).
Furthermore, depending on the flight conditions of the aircraft, in particular at takeoff or when the aircraft is flying vertically stationary (or VTOL mode) or at low speed near above a surface such as the ground, the direction of flow of the airflow around the aircraft, in particular around the nacelle cowling of the propulsion system of the aircraft. In fact, under these conditions, the air flow ejected behind the rotor can cause damage to the surface under the aircraft, which deviates the trajectory of the air flow and alters the direction of flow of the air flow around the aerodynamic profile that constitutes the nacelle fairing. Thus, depending on the position of cruising flight or flight away from obstacles, the aerodynamic characteristics of the nacelle cowling change. When an aircraft is flying vertically, at rest or at low speed, sufficiently close above a surface, the surface affects the airflow flow circulation around the aircraft, particularly around the nacelle fairing. This phenomenon is called the "ground effect".
For the desired aerodynamic performance, it is advantageously possible to adapt the shape of the aerodynamic profiles constituting the nacelle fairing in the respective flight conditions of the aircraft (in particular when the "ground effect" has a great influence).
Various solutions have been proposed in the prior art to adapt to the shape of the aerodynamic profile of an aircraft under various flight conditions, but most of these solutions are directed to the wing of the aircraft, which solutions cannot be transferred to or adapted to axisymmetric elements such as the nacelle fairing of a propulsion system (for example a turbojet or an electric impeller).
Dual-flow turbojet engines have been proposed which make it possible to locally vary the geometry of the secondary jet, or which have been proposed with variable inlet section of the nacelle cowls.
However, none of these proposed solutions proposes adapting the outlet or inlet section of the nacelle fairing of the propulsion system (in particular in rotor VTOL mode) to the flight conditions of the aircraft.
Therefore, in view of the above problems, it is desirable to provide a simple and efficient solution.
The invention aims to provide a scheme capable of simply and quickly adapting a propulsion system of an aircraft, so that the aerodynamic and acoustic properties of the propulsion system are improved, and the safety of a rotor is guaranteed at each flight phase of the aircraft.
Disclosure of Invention
To this end, the invention relates to a propulsion system for an aircraft comprising at least one rotor and a nacelle fairing extending around an axis of rotation of the at least one rotor with respect to the rotor, the nacelle fairing comprising:
-a front section forming an inlet section of the nacelle fairing;
-a rear section, the end of which forms an outlet section of the nacelle fairing; and
-a middle section connecting the front section and the rear section;
characterised in that the rear section comprises a radially inner wall and a radially outer wall, the radially inner wall and the radially outer wall being made of a shape memory material, and in that the aeronautical propulsion system comprises at least one drive mechanism of a jack configured to cooperate with means embedded in the inner surface of the radially outer wall to vary the outer diameter of the outlet section between the determined minimum diameter and maximum diameter.
The propulsion system of the invention thus makes it possible to obtain simply and quickly, according to the needs of the aircraft, a nacelle fairing shape adapted to the flight conditions of the aircraft, ensuring optimum propulsion efficiency, while minimizing the acoustic hazards posed by the rotor of the propulsion system, and the presence of the nacelle fairing ensuring the safety of this rotor. In other words, an advantage of the propulsion system is that the presence of the nacelle fairing enables the nacelle fairing to be adapted according to the flight conditions of the aircraft.
An inlet cross-section of an engine compartment fairing of the propulsion system may correspond to a leading edge of the fairing. The outlet cross section of the fairing may correspond to the trailing edge of said fairing. Thus, the outer diameter of the trailing edge may correspond to the outer diameter of the outlet cross section of the propulsion system.
According to another embodiment, the means embedded in the radially external wall comprise a plurality of prisms distributed in at least one annular row, the plurality of prisms being driven by at least one jack through at least one annular element.
Advantageously, the propulsion system further comprises a reinforcement shroud connecting the radially inner wall and the radially outer wall of the rear section and making it possible to ensure that the clearance between the radially inner wall and the radially outer wall of the rear section is substantially constant, in particular from a convergent position to a divergent position or vice versa of the rear section of the nacelle fairing of the propulsion system.
Advantageously, the intermediate section is rigid and connected to the engine of the propulsion system by at least one arm.
This gives the nacelle cowling of the propulsion system a rigid structure to ensure the screening function.
Preferably and advantageously, the front section is made of a deformable shape memory material and comprises means for varying the outer diameter of the inlet section of the propulsion system.
In this way, the nacelle fairing of the propulsion system of the invention can be easily adapted according to the flight phase of an aircraft equipped with this propulsion system.
According to one embodiment, the outer diameter of the inlet section is varied by a pneumatic or hydraulic expansion device.
The advantage of this solution is that it does not require a large amount of energy for its implementation.
According to another embodiment, the outer diameter of the inlet section is varied by the annular thermal liner and the front section further has thermal contraction characteristics.
The technical scheme is simple to realize and has smaller volume and mass.
According to another embodiment, the outer diameter of the inlet section is varied under the action of a jack drive mechanism configured to cooperate with means fixed to the inner surface of the radially outer wall of the front section.
According to another embodiment, the outer diameter of the inlet section is varied under the action of a pneumatic or hydraulic annular actuator configured to deform radially under the action of a predetermined control pressure.
Advantageously, the front section comprises a plurality of stiffeners connected by a buckling-resistant device. This makes it possible to maintain a uniform aerodynamic profile of the inlet section of the nacelle fairing of the propulsion system of the invention.
The invention also relates to an aircraft characterised in that it comprises a propulsion system having at least one of the features described above, which is pivotally mounted on the aircraft by means of a pivot axis which is eccentric or through-disposed with respect to the rotor.
As mentioned above, the nacelle fairing of the propulsion system of the invention can be easily adapted according to the flight phase of the aircraft equipped with this propulsion system, and according to the translational or vertical flight mode of the aircraft.
Drawings
Other features and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings. In the drawings:
FIG. 1a is a perspective view of a first embodiment of a propulsion system having a nacelle mounted on an eccentric pivot shaft, the propulsion system being in a horizontal position;
FIG. 1b is a view similar to FIG. 1a and showing the propulsion system in a vertical position;
FIG. 1c is a perspective view of a second embodiment of a propulsion system having a nacelle mounted on a through pivot shaft, the propulsion system being in a horizontal position;
FIG. 2 is a cross-sectional view of the propulsion system of the present invention with the aft section of the nacelle fairing in a converging position;
FIG. 3 is a view similar to FIG. 2 and showing the propulsion system of the present invention with the aft section of the nacelle fairing in an intermediate position;
FIG. 4 is a view similar to FIG. 2 and showing the propulsion system of the present invention with the aft section of the nacelle fairing in a diverging position;
FIG. 5a is a partial cross-sectional view of a nacelle fairing with an aft section in a converging position;
FIG. 5b is a view similar to FIG. 5a and showing the aft section in a diverging position;
FIG. 5c is a longitudinal cross-sectional view of the aft section of the nacelle fairing shown in a converging position;
FIG. 5d is a longitudinal cross-sectional view of the aft section of the nacelle fairing shown in a diverging position;
FIG. 5e is a transverse cross-sectional view of the aft section of the nacelle fairing shown in a converging position;
FIG. 5f is a transverse cross-sectional view of the aft section of the nacelle fairing shown in a diverging position;
FIG. 6a is a partial cross-sectional view of the nacelle fairing of the propulsion system of the present invention and showing the inlet of the nacelle fairing in a neutral position;
FIG. 6b is a view similar to FIG. 6a and showing the inlet of the nacelle fairing in a converging position;
FIG. 6c is a longitudinal cross-sectional view of the forward section of the nacelle fairing shown in a converging position;
FIG. 7a is a cross-sectional view of an inlet of a nacelle fairing of the propulsion system, the inlet being in a neutral position;
FIG. 7b is a view similar to FIG. 7a and showing the inlet of the nacelle fairing of the propulsion system in a converging position;
FIG. 7c is a partial front view of an inlet of a nacelle fairing of the propulsion system;
FIG. 8a is a front view of one embodiment of the ring driver of the present invention;
FIG. 8b is a cross-sectional view of an embodiment of the ring drive of the present invention, shown in the rest position;
figure 8c is a cross-sectional view of an embodiment of the ring driver of the present invention shown in a converging position.
Detailed Description
The terms "axial", "inner" and "outer" are used herein with reference to the axis of rotation of the propulsion system of the present invention.
The propulsion system generally comprises:
-an engine compartment;
-an engine and its steering control system; and
in the case of propeller or rotor propulsion, a propeller or rotor.
The nacelle is an element that can be integrated with the engine of an aircraft, the nacelle comprising:
nacelle cowlings (enabling the engine to be inverted, streamlining the rotor, directing the air flow according to the operation of the aircraft, generating thrust actions, reversing the thrust of the propulsion system, etc.);
engine-mounted devices (e.g. Engine mounts for converged electric, hydraulic, pneumatic networks, i.e. Engine built-Up, EBU); and
-a suspension system (sysste d' accharge) suspended to the aircraft.
Fig. 1a and 1b show in a simplified manner a first embodiment of a propulsion system 1 of an aircraft according to the invention.
Here, the propulsion system 1 comprises at least one rotor 2 and a nacelle fairing 3, the nacelle fairing 3 extending around a rotation axis X of the at least one rotor 2 relative to the rotor 2. The propulsion system 1 may be fixedly mounted on an aircraft. The propulsion system 1 may also be mounted on the pivot shaft 4 and eccentric with respect to the rotation axis X of the rotor 2. The pivot axis 4 is fixed to the propulsion system 1 on the one hand and to the aircraft on the other hand by any means and enables the orientation of the propulsion system on the aircraft, allowing the propulsion system 1 to be steered by means of known actuators about the pivot axis 4 between a horizontal position as indicated by the arrow F1 in fig. 1a and a vertical direction as indicated in fig. 1 b. This steering enables the aircraft to be converted from a typical mode of the aircraft to a VTOL or helicopter mode.
The rotor 2 of the propulsion system 1 is connected to the aircraft by means of a strut 5 supporting an engine 6 (for example an electric motor), so that the rotor 2 is driven in rotation by a power shaft in a known manner. According to the non-limiting example shown, each rotor 2 comprises two blades 7.
Fig. 1c shows a second embodiment of the propulsion system 1' of the aircraft of the invention, wherein the propulsion system ' may be mounted on a pivot axis 4' extending through the rotor 2 perpendicular to the axis of rotation X of the rotor 2. The rotor 2 of the propulsion system 1' is connected to the aircraft by means of a strut 5 supporting an engine 6 (for example an electric motor), so that the rotor 2 is driven in rotation by a power shaft in a known manner. According to the embodiment shown, the strut 5 of the rotor 2 is the same element (confondu) as the pivot axis 4'.
Referring to fig. 2 to 6, the nacelle fairing 3 of the propulsion system 1, 1' of the invention comprises:
-a front section 10;
-a rear section 20; and
an intermediate section 30 connecting the front section 10 and the rear section 20.
The forward section 10 forms the leading edge or air inlet section BA of the nacelle fairing 3. Preferably and advantageously, the front section 10 is made of deformable shape memory material and comprises an outer diameter D such as to give the inlet section BA of the propulsion system an inlet section BABAA variant arrangement.
The material comprising the front section 10 is both rigid to give the front section 10 a structural shape, and flexible to give the front section 10 the possibility of deformation, and is therefore referred to as "semi-rigid". Thus, the front section 10 is made of a material that is capable of reacting to the action of the actuator as described below. When the driver excites the front section 10, the front section 10 is in a structurally convergent shape; and when the activation constraint of the driver ceases, the front section 10 reverts to the original shape. Thus, the material comprising the front section 10 may be an alloy, compound or organic material that enables the front section 10 to operate in the elastic range. For example, the anterior segment 10 employs a nickel titanium alloy (also known as "Kiokalloy"), such as NiTiNol or NiTiCu.
More precisely, with reference to fig. 6a to 7c, the front section 10 comprises an annular front wing 11 and an annular rear portion 12. The annular rear portion 12 includes a radially inner wall 12a and a radially outer wall 12 b. The radially inner wall 12a and the radially outer wall 12b are connected at the front to the wings 11 and at the rear to the intermediate section 30.
The object of the invention is to make available an air inlet section of the nacelle fairing 3 of a propulsion system 1, 1', in particular a nacelleThe shape of the aerodynamic profile of the fairing can vary. In other words, the outer diameter D of the inlet cross-section BABACan vary and thus the aerodynamic shape of the front section 10 can vary between a convergent configuration and a neutral configuration. In the convergent configuration, the airflow duct at the inlet of the nacelle fairing 3 has a convergent shape; in the neutral configuration, the airflow duct at the inlet of the nacelle fairing 3 has a substantially cylindrical neutral shape.
FIGS. 6a and 6b schematically show the outer diameter D of the inlet section BABAChange between a neutral position (fig. 6a) and a convergent position (fig. 6 b). The outer diameter DBA has a minimum value D at the neutral positionBAminAnd has a maximum value D at the convergence positionBAmax. Thus, the outside diameter D at the convergent positionBAmaxGreater than the outside diameter D at neutral positionBAminAnd the inlet of the nacelle fairing 3 (otherwise known as the forward section 10) is said to be convergent. In other words, the jet air flow is varied so that the radial dimension of the air inlet section is greater than the radial dimension of the air outlet section. Thus, fluid rather than geometric definition is used herein for convergence.
According to a first advantageous embodiment, in order to obtain the outside diameter D of the inlet section BABAVarying between the neutral position and the convergent position or vice versa, the front section 10, more precisely the radially inner wall 12a and the radially outer wall 12b of the annular rear portion 12 of the front section 10, are made of a material having heat-shrink properties, which is capable of deforming, i.e. shrinking, when heated. To this end, the radially outer wall 12b of the annular rear portion 12 also comprises an annular thermal coating 13, the annular thermal coating 13 being intended to provide heat to deform, more precisely to shrink, the radially outer wall 12b of the front section. Thus, in the neutral position, as shown in fig. 6a, the radially inner wall 12a and the radially outer wall 12b have substantially the same axial dimension. Conversely, under the effect of the heat generated by the thermal coating 13, the radially outer wall 12b contracts, i.e. its axial dimension is reduced with respect to its neutral axial dimension, which drives the radially inner wall 12a to elongate, i.e. its axial dimension is increased with respect to its neutral axial dimension. As will be described below, the intermediate section 30 is rigid such that the forward section 10 passes through the radially inner wall 12a and radiallyThe outer wall 12b is fixed to the intermediate section 30 and the inlet section BA is free, so that the radially outer wall 12b is retracted and the radially inner wall 12a is extended, the actuating wing 11 (or the inlet section BA) being moved in the outer radial direction, indicated by the arrow F2 in fig. 6b, thereby actuating the outer diameter DBAAnd is increased.
The annular thermal coating 13 is heated in a known manner, for example by means of a resistive circuit arranged in the coating 13.
The radially inner wall 12a and the radially outer wall 12b of the annular rear portion 12 of the front section 10 are made of materials having the same shape memory characteristics, so that when the thermal coating 13 is not heated, the radially inner wall 12a and the radially outer wall 12b can recover the shape and the neutral axial dimension, and therefore the inlet section BA can also recover the neutral dimension DBAmin。
According to a second advantageous embodiment, shown in fig. 6c, in order to obtain the outer diameter D of the inlet section BABAVarying between a neutral position and a convergent position, and vice versa, the front section 10 comprises at least two jack-actuating mechanisms 230 arranged diametrically at equal distances, the jack-actuating mechanisms 230 being configured to cooperate with means 240 fixed on the inner surface 12b' of the radially outer wall 12b to cause the outer diameter D of the inlet section BA to be greater than the outer diameter D of the inlet section BABAVarying between a minimum diameter and a maximum diameter.
More precisely, the jack arm 230 'of the jack-actuating mechanism 230 is configured to be extended or retracted under a predetermined manipulation to act on the device 240 and to radially move the device 240, exerting a pressure on the radially inner surface 12b' of the radially outer wall 12b and thus causing the outer diameter D of the inlet section BABAAnd (4) changing. The jack drive mechanism 230 may be an electric, hydraulic, pneumatic, or screw-nut system.
For example, the device 240 is embedded in the radially inner surface 12b' of the radially outer wall 12b (e.g. by vulcanization) and is moved radially under the action of the jack drive mechanism 230.
According to an embodiment, the device 240 comprises a plurality of prisms (for example triangular in section) distributed in at least one annular column, driven by at least one jack through at least one annular element 250.
Prism 240 and ring member 250 are formed of a rigid material, such as a metal material.
In fig. 6c, the forward section 10 of the nacelle fairing 3 is in a convergent position with the jack arm 230' of the jack drive mechanism 230 fully extended.
Actuation of the jack drive mechanism 230 drives the jack arms 230' to extend, thereby driving the annular member 250 to move axially (in the direction of arrow F5 in fig. 6 c) and thereby driving the prism columns 240 to move radially (in the direction of arrow F6). The annular element 250 moves on the face of the prism 240 between a neutral position of the front section of the nacelle fairing 3 (in a position flush with the inner surface 12b' of the inner wall 12b) and a convergent position of the front section 10 of the nacelle fairing 3 (in a position close to the apex of the prism 240). The prism 240 is embedded in the radially inner surface 12b' of the radially outer wall 12b and the annular element 250 is rigid, the diameter of the radially outer wall 12b and of the radially inner wall 12a increasing under the thrust action radially of the prism 240, driving the diameter of the inlet section BA to increase, thus shifting the front section 10 of the nacelle fairing 3 to the convergent configuration shown in fig. 6 c. Advantageously, the faces of the prisms 240 and of the annular element 250 are covered with an anti-friction coating.
When the jack drive mechanism 230 is actuated to retract the jack arm 230', the elements move in opposite directions to reduce the diameter of the entry section BA. The radially inner wall 12a and the radially outer wall 12b of the forward section 10 are of a shape memory material to return the forward section 10 of the nacelle fairing 3 to the neutral configuration shown in figure 6 a.
Advantageously but not limitatively, each annular row comprises at least four prisms 240, the four prisms 240 being equi-angularly distributed along the radially inner surface 12b' of the radially outer wall 12b of the front section 10. It is easily understood that an increased number of prisms allows a better distribution of the radial thrust and therefore a better axial symmetry of the front section 10 of the nacelle fairing 3 in the convergent position.
It is also conceivable that the propulsion system 1, 1' comprises a plurality of rows of prisms 240 and a jack drive mechanism 230 separate for each annular row of prisms 240.
According to another embodiment, not shown, the annular crown is directly connected to the jack arm 230' of each drive mechanism 230. Each annular crown then slides directly (converges to rest) on the inner surface 12b' of the outer wall 12 b. Advantageously, the inner surface 12b' of the outer wall 12b is then provided with an anti-friction coating.
The transition of the front section 10 of the nacelle fairing 3 from the convergent configuration to the neutral configuration (or vice versa) is continued in response to the extension or retraction of the jack arm 230' of the drive mechanism 230.
According to a third advantageous embodiment, not shown, in order to obtain the outside diameter D of the inlet section BABAVarying between the neutral position and the convergent position (or vice versa), the inlet section BA of the nacelle fairing 3 comprises a pneumatic or hydraulic annular actuator 40 extending around the rotation axis X of the rotor 2. The annular driver 40 is configured to deform radially under a predetermined operating pressure to cause the outer diameter D of the inlet section BABAVarying between a minimum diameter and a maximum diameter.
More precisely, annular actuator 40 is configured to deform radially under a predetermined operating pressure so as to cause outer diameter D of inlet section BABABetween a neutral position and a convergent position of the front section 10 of the nacelle fairing 3. For this purpose, the annular drive is connected to known pneumatic or hydraulic automation devices, so that by applying an operating pressure adapted to the required convergent or neutral position of the rear section 10 of the nacelle fairing 3, a fluid can be introduced into or withdrawn from the annular drive 40.
Preferably and advantageously, the annular actuator 40 is made of a radially reinforced elastomeric material, for example comprising fibers. For example, the annular drive 40 employs a polymeric material that contains external devices or inclusions to strengthen the polymeric material in a radial direction.
According to another embodiment shown in fig. 8a to 8c, the annular actuator 40 comprises an annular pocket 40a of flexible material (vesse) 40a inserted into a helical spring 40b, so as to limit the diametrical expansion of the section of the flexible pocket 40 a. Another embodiment can use an anisotropic (orthopipe) material having a greater elastic modulus in the radial direction relative to the azimuthal direction.
The ring driver 40 is configured such that, upon an increase in the pressure experienced, the inner cross-sectional diameter d of the ring driver40Is much smaller than the outer diameter D of the ring driver 4040The expansion of (2). In other words, the increased pressure inside the annular driver 40 (or flexible bag 40a) is expressed as having the outer diameter D of the annular driver 4040The increasing direction angle expands.
In fact, the gradual increase of the operating pressure generated by the pneumatic or hydraulic automatic means causes the outer diameter D of the annular actuator 40 to increase40Gradually changing so as to deform the radially inner wall 12a and the radially outer wall 12b of deformable shape-memory material of the front section 10 and thus the outer diameter D of the inlet section BABAFrom the minimum diameter D in the neutral configuration shown in FIG. 6aBAminTo the maximum diameter D in the convergent configuration of the forward section 10 of the nacelle fairing 3 shown in fig. 6bBAmax。
Likewise, the progressive reduction of the operating pressure generated by the pneumatic or hydraulic automatic means causes the progressive transformation of the front section 10 of the nacelle fairing 3 from the convergent configuration shown in fig. 6b to the neutral configuration shown in fig. 6 a.
The transition of the front section 10 of the nacelle fairing 3 from the neutral configuration to the convergent configuration (or vice versa) is carried out continuously according to the operating pressure generated by the pneumatic or hydraulic automatic means.
According to another embodiment, not shown, the outer diameter D of the inlet section BA is made such thatBAThe means capable of changing between a neutral position and a convergent position (or vice versa) comprise pneumatic expansion means. Thus, pressurized air is injected into the annular front wing 11 to move it in a radially outward direction, driving the retraction of the radially outer wall 12b and the extension of the radially inner wall 12a of the annular rear portion of the front section 10 and therefore the driving of the outer diameter D of the inlet section BABAAnd is increased. The walls 12a, 12b are made of deformable shape-memory material so as to restore the shape of the walls and the neutral axial dimension when the pneumatic expansion device takes the air out of the annular front wing 11, and therefore so as to restore the inlet section BA also to the neutral dimension DBAmin。
Thus, the outer diameter D of the inlet section BA of the nacelle cowl 3 can be easily adjustedBAThe possibility of making modifications makes it easy to adapt the inlet profile of the nacelle fairing 3 according to the various flight phases of the aircraft equipped with the propulsion system 1, 1 'of the invention, i.e. according to the aeromechanical and dynamic constraints in the operation of the propulsion system 1, 1'. Thus, during static flight phases close to the ground, for example, by converging the air into the nacelle cowling and thus having an outer diameter D of the inlet section BA as large as possibleBAThe lift generated by the nacelle fairing 3 is increased, in flight mode or in phases of flight away from the ground, obtaining a higher propulsive efficiency and therefore having an outer diameter D of the inlet section BA as small as possibleBA。
The front section 10 is made of a deformable material suitable to ensure a rigid structure, so as to avoid, when the propulsion system 1, 1' is operating, the presence of concavities at rest due to the action of the air flow, and thus to allow the nacelle fairing 3 to maintain a uniform aerodynamic profile of the inlet section BA. The front section 10 thus advantageously comprises a plurality of stiffeners 14, these stiffeners 14 being connected by a buckling-resistant device 15.
Referring to fig. 7a to 7c, a plurality of stiffeners 14 are provided in the annular front wing 11 of the front section 10 and are distributed angularly as shown in fig. 7 c.
These stiffeners (e.g., metal stiffeners) have an aerodynamic profile with a C-shaped cross section, corresponding to the aerodynamic shape of the inlet cross section BA of the nacelle fairing 3. A radially outer arm 14B of the reinforcement 14 opposite the radially inner arm 14a has a receiving groove 16 of the anti-buckling device 15, the receiving groove 16 being provided in the arm 14B and extending from the radially inner surface 14B' along the axis B.
According to the example shown, the anti-buckling device 15 comprises a rigid ring, for example a metal ring. The buckling-resistant device 15 thus inserted into the groove 16 of each stiffener 14 acts as a reinforcement to ensure that the stiffener 14 is connected into the annular front wing 11.
The slot 16 has a semi-elliptical shape inclined at an angle a relative to the longitudinal axis a of the reinforcing element 14.
Referring to FIG. 7a, currentlySegment 10 is in a neutral position such that the outer diameter D of inlet section BABAIs a minimum value DBAminAt the time, the stiffener 14 is in a rest position in which the longitudinal axis a of the stiffener 14 is substantially parallel to the rotation axis X of the rotor 2 of the propulsion system 1, 1', and the buckling-resistant ring 15 is placed against the bottom of the groove 16 of the stiffener 14.
Referring to FIG. 7b, the front section 10 converges to cause the outer diameter D of the inlet section BABAIncrease to a maximum value DBAmaxAt the time, the reinforcement 14 is in an inclined position in which the longitudinal axis a of the reinforcement 14 is inclined along an angle β with respect to the rotation axis X of the rotor 2 of the propulsion system 1, 1', and the buckling-resistant ring 15 is always engaged in the groove 16 and in a position not coming out of the radially inner surface 14b' of the radially outer arm 14b of the reinforcement 14.
However, in order to obtain the outer diameter D of the inlet section BABAIn a variant, such an anti-buckling device 15 is not necessary for embodiments employing a prism 240, a jack drive mechanism 230 and an annular element 250, which elements (230, 240, 250) already guarantee the anti-buckling function.
The front section 10, in particular the annular front wing 11, is still configured to ensure the anti-icing function of the inlet of the nacelle fairing 3. The material actually used for the front section 10 configures the front section 10 to be able to withstand a large temperature difference, so that the front section 10 can secure the anti-icing function when supplied with hot air.
The intermediate section 30 is rigid. For example, the front section 10 employs aluminum alloy, Ta6V, or a carbon-based fiber composite.
The intermediate section 30 is advantageously connected to the engine 6 of the propulsion system 1, 1 'by at least one arm 31, preferably two arms 31, so as to be mechanically fixed to the nacelle cowling 3 of the engine 6 of the propulsion system 1, 1'. The material and the configuration of the intermediate section 30 thus provide it with the function of shielding the propulsion system 1, 1'.
The end 21 of the rear section 20 forms the outlet cross section BF (or trailing edge BF) of the nacelle fairing 3.
The rear section 20 includes a radially inner wall 20a and a radially outer wall 20 b.
The radially inner wall 20a and the radially outer wall 20b of the rear section 20 ensure not only the structural function of the rear section 20 but also the aerodynamic function.
The radially inner wall 20a and the radially outer wall 20b of the posterior segment 20 are formed of a deformable, semi-rigid shape memory material. In other words, the material comprising the radially inner and outer walls 20a, 20b of the aft section 20 is both rigid to give the aft section 20a structural shape, and flexible to allow the aft section 20 to deform. The radially inner wall 20a and the radially outer wall 20b of the rear section 20 are therefore of a material which is capable of reacting to the action of the actuator as described hereinafter. When the radially inner wall 20a and the radially outer wall 20b of the rear section 20 are excited by the driver, the radially inner wall and the radially outer wall deform and have a structural shape (i.e. a neutral divergent shape and no convergent excitation), and when the excitation constraint of the driver ceases, the radially inner wall and the radially outer wall return to the original shape. The material constituting the radially inner wall 20a and the radially outer wall 20b may be an alloy, a compound, or an organic material that enables the radially inner wall 20a and the radially outer wall 20b to operate in an elastic range. For example, the radially inner wall 20a and the radially outer wall 20b are made of a nickel titanium alloy (also referred to as "Kiokalloy"), such as nitinoil or NiTiCu.
The shape memory material constituting the radially inner wall 20a and the radially outer wall 20b has an overall safety, that is to say the resting state of the material, i.e. when the actuator does not act on the deformed shape memory material, corresponds to the natural geometry of said material for storage or longer periods of use, i.e. in the case of the rear section 20 of the nacelle fairing 3 for the aircraft 1, 1', this corresponds to the convergent shape of the rear section 20. Thus, when the actuator fails, the shape memory material returns to the natural resting shape and the nacelle fairing 3 returns to the safety geometry to ensure the proper functioning of the aircraft's propulsion system 1, 1'.
The thickness of the radially inner wall 20a and the radially outer wall 20b varies axially and azimuthally in the vicinity of the reinforcing retainer 22, thereby locally changing the elasticity of the shape memory material constituting the radially inner wall 20a and the radially outer wall 20 b. The mechanical properties of the shape memory material forming the radially inner wall 20a and the radially outer wall 20b may also be locally optimized according to the desired local properties along the rear section 20. Thus, it is contemplated that the rear section 20 includes a plurality of sections made of different materials.
The rear section 20 is made of a semi-rigid material to ensure a rigid structure of the rear section 20, so as to avoid, when the propulsion system 1, 1' is operating, the presence of concavities at rest due to the action of the air flow and thus allow the nacelle fairing 3 to maintain a uniform aerodynamic profile of the outlet section BF. Advantageously, the rear end portion 21 of the rear section 20 is made of an anisotropic material having a suitable modulus of elasticity.
In addition, to ensure a substantially constant gap between the radially inner and outer walls 20a, 20b of the aft section 20, reinforcing retainers 22 are distributed at fixed angular intervals between the radially inner and outer walls 20a, 20 b.
The rear section 20 further comprises an outer diameter D such that the outlet cross section BFBFAt the smallest outer diameter DBFcAnd a maximum outer diameter DBFdOf minimum outer diameter DBFcMaximum outside diameter D corresponding to the convergent position of the rear section 20 of the nacelle cowl 3BFdCorresponding to the divergent position of the rear section 20 of the nacelle fairing 3. Furthermore, the terms "converging" and "diverging" as used with reference to the posterior segment 20 are based on fluid rather than geometric considerations.
In fact, another object of the present invention is to enable the shape of the air outlet cross-section of the nacelle fairing 3 of the propulsion system 1, 1', in particular the aerodynamic profile of the nacelle fairing, to be varied. In other words, the outer diameter D of the outlet cross-section BFBFCan vary and thus the aerodynamic shape of the rear section 20 can vary between a convergent configuration and a neutral configuration. In the convergent configuration, the airflow duct at the outlet of the nacelle fairing 3 has a convergent shape; in the diverging configuration, the airflow duct at the outlet of the nacelle cowling 3 has a diverging shape.
In other words, for a streamlined rotor, the outlet air profile of the nacelle fairing 3 has a convergent shape, maximizing the thrust generated by the nacelle fairing 3 and therefore the efficiency of the thrust assembly, at each flight phase of the aircraft in which the ground effect can be neglected; for other phases, such as stationary flight of the aircraft in which there is a ground effect, the outlet air profile of the nacelle fairing 3 preferably has a divergent shape, since the thrust generated by the nacelle fairing 3 is maximized under this condition.
To this end, the rear section 20 has at least two jack-driving mechanisms 23 arranged diametrically equidistantly, the jack-driving mechanisms 23 being configured and fixed on the inner surface 20b' of the radially outer wall 20b such that the outer diameter D of the outlet section BF is suchBFVarying between a minimum diameter and a maximum diameter.
More precisely, the jack arm 23' of the jack-actuating mechanism 23 is configured to be extended or retracted under a predetermined manipulation so as to act on and radially move the device 24, 24', generating a thrust on the radially inner surface 20b ' of the radially outer wall 20b and causing the outer diameter D of the outlet section BFBFAt a convergent diameter DBFcAnd a divergent diameter DBFdChange in diameter D of convergenceBFcCorresponding to the convergent configuration of the rear section 20 of the nacelle fairing 3 with the jacks 23 retracted; divergent diameter DBFdCorresponding to the diverging configuration of the rear section 20 of the nacelle fairing 3 and with the jacks 23 fully extended. The jack drive mechanism 23 may be an electric, hydraulic, pneumatic, or screw-nut system.
Preferably, the rear section 20 comprises at least two means 24, 24', these two means 24, 24' being equally distributed (for example, in the angular positions of 6 o 'clock and 12 o' clock) in particular for pushing the annular elements 25, 26 and the connecting rod 27.
The devices 24, 24 'are embedded (for example by vulcanisation) in the radially internal surface 20b' of the radially external wall 20b and are radially moved by the jack drive mechanism 23.
According to an embodiment, the device 24, 24' comprises a plurality of prisms distributed in at least one annular row, driven by at least one jack through at least one annular element 25.
Referring to fig. 5a and 5b, the device 24 comprises a plurality of prisms (e.g. having a triangular cross-section) distributed in two annular columns. The first annular row of prisms 24 is connected to each jack arm 23' of the jack drive mechanism 23 by a first annular element 25. The prism 24' of the second annular row is connected to the prism 24 of the first annular row, more precisely to the first annular element 25, by means of a second annular element 26 and at least two rods 27, preferably a plurality of connecting rods 27, arranged in the 12 o ' clock and 6 o ' clock directions. The prisms 24, 24', the annular elements 25, 26 and the connecting rods 27 are made of a rigid material, for example a metallic material.
In fig. 5a, the rear section 20 of the nacelle fairing 3 is in a convergent position with the jack arms 23' of the jack drive mechanism 23 fully retracted. The radially inner wall 20a and the radially outer wall 20b are in an unexpanded state (i.e., the radially inner wall 20a and the radially outer wall 20b are stationary). The convergent arrangement of the rear section 20 of the nacelle fairing 3 is such that the diameter of the radially inner wall 20a gradually decreases in the direction towards the outlet cross-section BF.
Actuation of the jack drive mechanism 23 drives the jack arms 23 'to extend, driving the first annular element 25 to move axially (in the direction of arrow F3 in fig. 5 b), the first column of prisms 24 (in the direction of arrow F4) to move radially outwardly and the rods 27 and second annular element 26 (in the direction of arrow F3) to move axially, driving the second column of prisms 24' (in the direction of arrow F4) to move radially outwardly. The prisms 24, 24' are embedded in the radially inner surface 20b ' of the radially outer wall 20b and the annular elements 25, 26 are rigid, the diameter of the radially inner wall 20a increases under the radial thrust of the prisms 24, 24 '. The increase in diameter of the radially inner wall 20a leads to an increase in diameter of the outlet section BF. The radially inner wall 20a and the radially outer wall 20b of the rear section 20 are made of deformable material, and the change in geometry of the radially outer wall 20b causes the rear section of the nacelle fairing 3 to be shifted to the diverging configuration shown in fig. 5b, in particular by means of the retainer 22 driving the change in geometry of the radially inner wall 20a in the direction of the arrow F4.
Thus, as shown in fig. 5c to 5f, the annular elements 25, 26 move on the faces of the prisms 24, 24' between a convergent position of the rear section 20 of the nacelle fairing 3 (position flush with the inner surface 20b ' of the inner wall 20b) and a divergent position of the rear section 20 of the nacelle fairing 3 (position close to the apex of the prisms 24, 24 '). Advantageously, the faces of the prisms 24, 24' and of the annular elements 25, 26 are covered with an anti-friction coating.
As shown in fig. 5c and 5d, the prisms 24 of the first annular column (closer to the intermediate section 30) and the prisms 24' of the second annular column (closer to the exit cross-section BF) have different dimensions. In particular, the apex angle θ 'of prism 24' is less than the apex angle θ of prism 24. Indeed, it can be understood that, in order to transform the rear section 20 of the nacelle fairing 3 from a convergent position to a divergent position, the inner wall 20a and the outer wall 20b are displaced with a variable increase in amplitude as they approach the outlet section, the prisms 24, 24' being therefore configured so that the radial displacement of the inner wall 20a and of the outer wall 20b has a variable amplitude, so that the annular elements 25, 26 have the same axial displacement.
As described hereinbefore, the first element 25 is axially displaced as shown in fig. 5e and 5f, such that the inner diameter of the first annular element 25 changes. For example, the diameter Dc of the first annular element 25 is largest when the aft section of the fairing is in a convergent position (fig. 5e), and the diameter Dc of the first annular element 25 is smallest when the aft section of the fairing is in a divergent position (fig. 5 f). Thus, the first annular element 25 has a diameter Dc at the convergent position which is greater than the diameter Df of the first annular element 25 at the divergent position.
When the jack drive mechanism 23 is actuated to retract the jack arm 23', the elements move in opposite directions to reduce the diameter of the exit section BF. The radially inner wall 20a and the radially outer wall 20b of the rear section 20 are made of a shape memory material to restore the rear section 20 of the nacelle fairing 3 to the convergent configuration shown in figure 5 a.
Advantageously, but not in a limiting manner, each annular column comprises at least four prisms 24, 24', the four prisms 24, 24' being equi-azimuthally distributed along the radially inner surface 20b ' of the radially outer wall 20b of the rear section 20. It will be readily appreciated that an increased number of prisms allows a better distribution of the radial thrust and therefore a better axial symmetry of the rear section 20 of the nacelle fairing 3 in the divergent position.
It is also conceivable that the prisms 24, 24 'of each circumferential row are connected to a dedicated jack mechanism 23 by means of a ring element, the propulsion system 1, 1' then comprising the same number of jack drive mechanisms 23 independent of each other as the circumferential rows of prisms 24.
According to another embodiment, not shown, the annular crown is directly connected to the jack arm 23' of each drive mechanism 23. Each annular crown then slides (converges to rest) directly on the inner surface 20b' of the outer wall 20 b. Advantageously, the inner surface 20b' of the outer wall 20b is then provided with an anti-friction coating.
Fig. 2 shows a propulsion system 1, 1' according to the invention, the rear section 20 of the nacelle fairing 3 of the propulsion system 1, 1' being mounted in a convergent configuration corresponding to a position in which the jack arms 23' of the drive mechanism 23 are fully retracted.
Fig. 3 shows a propulsion system 1, 1' according to the invention, the rear section 20 of the nacelle fairing 3 of the propulsion system 1, 1' being mounted at an intermediate position between the convergent configuration and the divergent configuration, the intermediate position corresponding to a position in which the jack arm 23' of the drive mechanism 23 is extending.
Fig. 4 shows a propulsion system 1, 1' according to the invention, the rear section 20 of the nacelle fairing 3 of the propulsion system 1, 1' being mounted in a divergent configuration, the convergent configuration corresponding to a position in which the jack arms 23' of the drive mechanism 23 are fully extended.
In fact, the progressive extension movement of the jack arms 23' of the drive mechanism 23 drives the means 24, 24' embedded in the inner surface 20b ' of the radially outer wall 20b to progressively move radially outwards, so as to deform the radially inner wall 20a and the radially outer wall 20b of the rear section 20, made of deformable shape-memory material, and thus the outer diameter D of the outlet section BFBFFrom the minimum diameter D in the convergent configuration shown in FIG. 2BFcThrough the intermediate position shown in fig. 3 to the maximum diameter D in the diverging configuration of the rear section 20 of the nacelle fairing 3 shown in fig. 4BFd。
Likewise, the progressive contracting movement of the jack arms 23' of the drive mechanism 23 causes the nacelle fairing 3 to transition from the diverging configuration shown in fig. 4 to the converging configuration shown in fig. 2.
The transition of the rear section 20 of the nacelle fairing 3 from the convergent configuration to the divergent configuration (or vice versa) is continued in accordance with the extension or retraction of the jack arms 23' of the drive mechanism 23, the reinforcing guard ring 22 ensuring that, when the configuration of the outlet section BF (i.e. the trailing edge) of the nacelle fairing 3 is changed, there is a substantially constant clearance between the radially inner wall 20a and the radially outer wall 20b of the rear section 20.
The aerodynamic profiles of the inlet and outlet sections of the nacelle fairing 3 can therefore advantageously be optimized between a diverging configuration and a converging configuration according to the aerodynamic and mechanical constraints obtained during the working phase of the aircraft, so as to form a diverging or converging flow respectively around the nacelle fairing.
The propulsion system 1, 1' according to the invention thus makes it possible to achieve simply and rapidly the convergence or divergence of the rear section 20 of the nacelle fairing 3 of the rotor 2 according to the requirements of the aircraft. The shape, construction and material of the nacelle cowls 3 of the propulsion system 1, 1 'according to the present invention thus enable it to form a sound barrier against the noise generated by the rotation of the rotor 2, ensure more attenuation of the emitted sound while ensuring increased safety of the rotor against obstacles accidentally present around, and ensure the propulsion effect of the nacelle cowls 3 of the propulsion system 1, 1' in stationary or low-speed forward flight.
The advantage of the aircraft equipped with the propulsion system 1, 1' of the invention is therefore that the divergent or convergent rear section 20 of the nacelle fairing of the rotor is provided as required, as well as the section of the nacelle fairing 3 which varies according to the flight conditions of the aircraft and the propulsion efficiency requirements of the aircraft, so as to give the aircraft the best aerodynamic performance. The rear section 20 of the nacelle fairing 3 is in a convergent position when the aircraft is in a flight phase at relatively high forward speeds. The rear section 20 of the nacelle fairing 3 is in the diverging position when the aircraft is taking off or when the aircraft is in a vertical flight phase above the surface and the ground effect is large.
Furthermore, the outer diameter D of the inlet cross-section BA (otherwise known as the leading edge) of the nacelle fairing 3BACan also be changed between a neutral position and a convergent position, thereby further improving the aerodynamics of the aircraftAnd (4) performance.
In fact, the variation of the inlet section combined with the variation of the outlet section makes it possible to vary the jet flow of the rotor propulsion system and therefore to significantly improve the aerodynamic performance of the aircraft.
