Internal structure of a nacelle for a turbine

Abstract

The internal structure (22) of a nacelle (18) for a turbine (10), the internal structure being designed to surround at least a part of a chamber that can receive a gas generator (14) of the turbine (10), the internal structure (22) including a ventilation cavity (30) of the chamber, the ventilation cavity (30) being provided with a main ventilation outlet (32) and an auxiliary ventilation outlet (34) separate from the main ventilation outlet (32), the internal structure (22) including a closing member (40) that is movable relative to the ventilation cavity (30) between a flow position and a closed position, in the closed position, the closing member (40) closing the auxiliary ventilation outlet (34) to a greater extent than in the flow position.

Description

Field of the Invention

[0001] The present invention relates, for example, to the field of nacelles of turbines installed on aircraft, and more particularly to improvements made to the internal structure of nacelles for turbines. Background Art

[0002] The turbines of aircraft are generally installed in nacelles that structurally support them while contributing to auxiliary functions for operating the aircraft, such as a mechanical thrust reverser system.

[0003] Document FR 2 966 435 A1 discloses a nacelle, the rear part of which exhibits a ventilation structure for the engine. This ventilation structure has a single annular outlet, the cross-section of which is selectively closed by a movable element so that it can adapt to contingencies that may cause pressure variations in the ventilation structure at all rated speeds during flight.

[0004] Although such nacelles are satisfactory, performance improvements are a constant concern in aeronautics. Therefore, a new type of internal structure for nacelles of turbines is needed. Summary of the Invention

[0005] To this end, the present invention relates to an internal structure for a nacelle of a turbine, which is intended to surround at least a part of a chamber capable of receiving a gas generator of the turbine, said internal structure including a ventilation cavity of said chamber, the ventilation cavity being provided with a main ventilation outlet and an auxiliary ventilation outlet separate from the main ventilation outlet, the internal structure including a closing member, said closing member being movable relative to the ventilation cavity between a flow position and a closing position, in which closing position, said closing member closes the auxiliary ventilation outlet to a greater extent than in said flow position.

[0006] A chamber (also called a core chamber) capable of receiving a gas generator of the turbine is provided to receive at least a part of the turbine that generates combustion gases, the energy of which combustion gases is then converted into mechanical energy intended to move the aircraft.

[0007] Thus, the internal structure can be annular and is intended to be arranged around the core chamber and the gas generator.

[0008] The ventilation cavity can be formed between a fairing of the core chamber and a nozzle. The ventilation cavity can include openings for the ventilation air flow to enter and exit the core chamber. In other words, the ventilation cavity receives the circulation of the ventilation flow of the gas generator. For this reason, the flow circulating in the cavity is sometimes called the "core vent".

[0009] The main ventilation outlet, or more simply the main outlet, includes one or more openings. Without loss of generality, one opening will be referred to herein from now on. The opening can be positioned such that in the normal operating mode, pressure guides air to pass through the opening in a direction starting from the interior of the cavity towards the exterior of the cavity. In other words, in normal operation, the air in the ventilation cavity can flow out via the opening, preferably outside the core compartment.

[0010] The auxiliary ventilation outlet, or more simply the auxiliary outlet, includes one or more orifices. Without loss of generality, several orifices will be referred to herein from now on. These orifices can be positioned such that in the normal operating mode, pressure guides air to pass through the orifices in a direction starting from the interior of the cavity towards the exterior of the cavity. In other words, apart from the closing member described below, the air from the ventilation cavity can flow out via these orifices, preferably discharged outside the core compartment.

[0011] The closing member is arranged to more or less close the auxiliary outlet in order to adjust its flow cross-section. In this way, the auxiliary outlet has a first flow cross-section when the closing member is in the flow position, and a second flow cross-section reduced relative to the first flow cross-section when the closing member is in the closed position. In this way, the displacement of the closing member changes the degree of blockage of the auxiliary outlet. The change in the flow cross-section of the auxiliary outlet according to the position of the closing member adapts the air outlet flow rate of the ventilation cavity during different operating modes and potential contingencies (such as a pressurized pipeline burst). It should be understood that there is no internal sealed separation between the main outlet and the auxiliary outlet in the cavity: the main outlet and the auxiliary outlet terminate in the same flow space inside the cavity. In other words, the flow that can flow out via the main outlet enters the cavity through the same inlet as the flow that can flow out via the auxiliary outlet.

[0012] Contrary to the devices of the prior art, where a single outlet is oversized to fit these different modes and cover contingency events, in the present invention, since the ventilation cavity has an auxiliary outlet separate from the main outlet and its flow cross-section can be adjusted, the size of the main outlet can be optimized without being oversized. The result is a potentially reduced diameter of the internal structure, and thus better compactness, reduced mass, and reduced resistance. The performance of the nacelle is accordingly improved.

[0013] In extreme cases, in the flow position, the closing member may not close the auxiliary outlet at all. Independently, in extreme cases, in the closed position, the closing member can completely close the auxiliary outlet. Each of these characteristics enables an expanded range of adjustment of the position of the closing member, and thus enables the benefits of freedom of size, precision, and performance to be obtained.

[0014] In some embodiments, the internal structure extends along a longitudinal axis, and the auxiliary ventilation outlet is offset relative to the main ventilation outlet, for example axially, radially, and / or tangentially. The auxiliary ventilation outlet can be in particular upstream of the main ventilation outlet, for example in the case where the main outlet is located at the downstream end of the ventilation cavity.

[0015] In some embodiments, the closing member is located inside the ventilation cavity. In this way, the closing member is located outside the core chamber and also outside the secondary flow path enclosing the internal structure. In this way, the closing member does not disrupt the most important flow for the aerodynamic performance of the turbine.

[0016] In some embodiments, the closing member includes a strip having a window, and in the flow position, the window faces at least partially towards the auxiliary ventilation outlet. In other words, by more or less aligning the window with the orifice of the auxiliary outlet, the auxiliary outlet allows more or less ventilation flow rate through. The window can be completely confined inside the strip, and / or as a cutout opening at the edge of the strip. The strip can be driven to slide. The strip can be flat, annular, or in a section of a ring, or of any shape.

[0017] In some embodiments, the closing member is rotatably movable, for example about the axis of the turbine (axis of the core chamber).

[0018] In some embodiments, the internal structure includes a control member configured to control the position of the closing member. The control member can be a passive member; the passive member can be automatically driven by a part of the turbine, or a part of the nacelle, or even by the flow circulating therein, without an active energy supply. Alternatively or additionally, the control member can be an active member; the active member can utilize an actuator powered by a dedicated energy source.

[0019] In some embodiments, the control member includes at least one profiled element configured to drive the closing member towards the flow position in the case of an increase in the ventilation flow in the ventilation cavity. The profiled element can be subjected to the ventilation flow in the ventilation cavity, or to a flow depending on the ventilation flow, and the force exerted by the flow on the profiled element drives the closing member towards the flow position. Such an embodiment is an example of a passive control member. In these embodiments, the control member automatically adapts the flow in the ventilation cavity by less obstructing the auxiliary outlet when a larger flow circulates in the ventilation cavity.

[0020] In some embodiments, the control member includes at least one return element configured to bias the closing member to return towards the closed position. The closed position can constitute the idle position of the closing member.

[0021] In some embodiments, the auxiliary ventilation outlet is arranged on one side of the ventilation cavity opposite to the chamber. In this way, the fact that the auxiliary outlet is more or less open does not disrupt the cooling of the core chamber. This "opposite side" can extend, in particular, in the radial direction of the turbine.

[0022] The invention also relates to a nacelle of a turbine comprising the internal structure as described above. Description of the Drawings

[0023] Other features and advantages of the object of the invention will become apparent from the following description of embodiments given by way of non-limiting examples with reference to the accompanying drawings.

[0024] Figure 1 is a longitudinal section of a turbine according to an embodiment.

[0025] Figure 2 is a perspective view of the internal structure according to an embodiment, with the closing member in the closed position.

[0026] Figure 3 is a perspective view of the internal structure according to an embodiment, with the closing member in the flow position.

[0027] Figure 4 is according to Figure 2 sectional view taken along plane IV-IV of

[0028] Figure 5 is according to Figure 3 sectional view taken along plane V-V of Detailed Description

[0029] Figure 1 The turbine 10 having a longitudinal axis X-X as shown in [specific reference] is of the turbofan type. The longitudinal axis X-X defines the axial direction. The radial direction is the direction perpendicular to and intersecting this axis. Similarly, the axial plane is the plane containing the longitudinal axis X-X, and the radial plane is the plane perpendicular to this axis. The circumference extends as a circle belonging to the radial plane, and the center of this circle belongs to the longitudinal axis X-X. The tangential or circumferential direction is the direction tangent to the circumference; it is perpendicular to the longitudinal axis X-X but does not pass through this axis.

[0030] As is known per se, the turbine 10 particularly includes a fan 12 driven by a gas generator 14 and an annular fan duct 16 externally delimited by a nacelle 18.

[0031] The turbine 10 also includes a central annular body 20 centered on the longitudinal axis X-X. In addition, the nacelle 18 includes an internal structure 22, which is annular here and at least partially surrounds the chamber (core chamber) that receives the gas generator 14. More precisely, the internal structure 22 is arranged coaxially around the central body 20, thus defining with the central body a main annular duct 24 for the flow of the air flow from the gas generator 14. Thus, the internal structure extends axially according to the longitudinal axis X-X.

[0032] As Figure 1 illustrated in detail by, the internal structure 22 includes a radially internal fairing 26 and a radially external nozzle 28. The fairing 26 and the nozzle 28 together form a ventilation cavity 30 in which the ventilation flow of the core chamber circulates. The nozzle 28 is radially disposed inside the annular fan duct 16 and is thus different from the nozzles inherent to the nacelle 18. Also, as shown in the figure, the ventilation cavity 30 is different from the annular fan duct 16 and the main annular duct 24.

[0033] As is known per se, the ventilation cavity 30 is provided with a main ventilation outlet 32 for discharging the said ventilation flow downstream of the turbine 10. The main outlet 32 is here formed by the space that separates the fairing 26 from the nozzle 28 at its downstream end. The flow flowing out from the main outlet 32 is guided by the nozzle 28. In this embodiment, the main outlet 32 includes a single opening, which is annular here and coaxial with the central body 20. The main outlet 32 here defines a plane, which is radial in this case, called the injection plane of the nozzle 28.

[0034] As previously pointed out, the ventilation cavity 30 also has an auxiliary ventilation outlet 34, which is also visible in Figure 2 this. Figure 2 The nozzle 28, as well as the main ventilation outlet 32 and the auxiliary ventilation outlet 34, are shown in perspective and without scale. For the sake of clarity, the fairing 26, the central body 20, and other elements of the internal structure 22 are not illustrated in Figure 2 this.

[0035] It is clear from the beginning that in this embodiment, the auxiliary outlet 34 is provided in the nozzle 28 rather than in the fairing 26; in other words, the auxiliary outlet 34 is arranged on the side of the ventilation cavity 30 opposite to the core chamber. However, as a variant, the auxiliary outlet 34 can be provided at another position on the ventilation cavity 30, usually in the fairing 26.

[0036] In the present embodiment, the auxiliary ventilation outlet 34 includes a plurality of orifices 36. For example, the orifices 36 can be distributed regularly or irregularly in the circumferential direction on the nozzle 28. The orifices can have any shape, such as the rectangular shape illustrated, or again polygonal, circular, elliptical, ovoid, rectangular, etc. For example, the rectangular or rectangular shape allows for a cost-effective implementation.

[0037] The upstream end of the orifice 36 can be axially located at a distance D1 from the injection plane of the nozzle 28, and the distance D1 is at least equal to one-fifth of the diameter D of the main outlet 32. In this way, the orifice 36 of the auxiliary outlet 34 can be long enough to have a significant influence on the flow flowing out of the ventilation cavity 30. The distance D1 is typically about 60 millimeters (mm), and more typically between 30 mm and 90 mm.

[0038] The downstream end of the orifice 36 can be axially located at a distance D2 from the injection plane of the nozzle 28, and the distance D2 is greater than or equal to 2 mm, preferably greater than or equal to 5 mm, and more preferably greater than or equal to 10 mm. In this way, the rigidity of the nozzle in its downstream part is maintained despite the presence of the orifice 36.

[0039] In this way, the orifice 36 can extend several centimeters, or even dozens of centimeters, in the longitudinal direction X-X. As a variant, a grid of orifices of relatively small size (e.g., less than 5 centimeters, or even less than 2 centimeters, or even less than 1 centimeter) has advantages in terms of aerodynamics and acoustics and can still be achieved by known methods and at reasonable cost. In the case of a grid of relatively small orifices 36, or more generally, in the case where some of the orifices 36 are axially offset relative to each other, the previous considerations apply separately to the farthest upstream and the farthest downstream orifices 36.

[0040] From the above and Figure 2 it appears that the auxiliary ventilation outlet 34 is axially offset relative to the main ventilation outlet 32. In this case, the orifice 36 is upstream of the main outlet 32, and the main outlet 32 is provided at the downstream end of the nozzle 28.

[0041] Moreover, the internal structure 22 includes a closing member 40. The closing member 40 is mounted to be movable relative to the ventilation cavity 30. In this embodiment, the closing member 40 includes a strip, which is configured as a ring here. The strip has one or more windows 42, which are multiple windows 42 in this case. The windows 42 can be distributed regularly or irregularly, circumferentially on the strip. The windows 42 are intended to be positioned relative to the orifices 36 so as to generate an air flow in the auxiliary outlet 34; in this regard, the windows 42 can have a shape, size, and / or arrangement corresponding to the shape, size, and / or arrangement of the orifices 36, as exemplified in Figure 3 described below. However, this is not necessary, and depending on the dimensions within the reach of those skilled in the art, as long as at least partial overlap of the orifices 36 and the windows 42 is sufficient to generate the said air flow, the windows 42 can have a shape, size, or arrangement different from the shape, size, or arrangement of the orifices 36.

[0042] The window 42 can be axially (transverse to the direction of displacement of the closing member 40) closed by an edge 44 without openings, at least on one side and preferably on each side. The edge 44 can increase the rigidity of the closing member 40 and limit leakage. For example, the edge 44 can axially extend a distance D3 greater than or equal to 2 mm, preferably equal to 5 mm, more preferably equal to 10 mm.

[0043] In Figure 2 the closing member 40 is shown in the closed position. In this case, except for inevitable leakage, the closing member 40 completely closes the auxiliary outlet 34. If necessary, such leakage can be reduced by a sealing joint (such as a brush or a flexible tab) or more generally any sealing means that allows the movement of the closing member 40 relative to the ventilation cavity 30. For example, these sealing joints can be provided on the periphery of the orifice 36 and / or the window 42.

[0044] It is noted that along the circumferential direction (the direction of displacement of the closing member 40), the width D4 of a given orifice 36a is less than the distance D5 between the orifice 36a and at least one adjacent orifice 36b. In this way, the window 42 corresponding to the orifice 36a can be completely offset from the orifice 36a, and the closing member 40 can completely block the orifice 36a.

[0045] In the present embodiment, the closing member is positioned inside the ventilation cavity 30 and thus, in this case, radially inside the nozzle 28. For example, the flow cross-section of the closing member 40 (except for the window 42) can be reduced by 0.1% to 5% relative to the flow cross-section of the nozzle 28, so that the closing member 40 can be radially accommodated inside the nozzle 28. Generally, the clearance provided between the radially outer surface of the closing member 40 and the inner surface of the nozzle 28 can be less than 5 mm, preferably less than 2 mm, more preferably less than 1 mm, for example for sealing reasons.

[0046] Moreover, the closing member 40 can rotate relative to the ventilation cavity 30 and thus relative to the nozzle 28. The internal structure 22 can be provided with any suitable system, such as elements known per se and not shown here, such as grooves, stops, fins, etc., to ensure a pivotal connection between the closing member 40 and the rest of the internal structure 22. According to an embodiment, these systems or elements can be provided on the complementary surfaces of the nozzle 28 and / or the closing member 40.

[0047] As previously pointed out, the closing member 40 is configured to shift from the closed position (an embodiment of which is illustrated in Figure 2 to the flow position (in Figure 3Examples of its embodiments are shown). In this embodiment, the movement between the closed position and the flow position can be performed by the rotation of the closing member 40, here about the longitudinal direction X-X, and additionally represented in the circumferential direction. When the ventilation cavity 30 receives an increased ventilation flow FFF, the displacement of the closing member 40 in the flow position can be completed ( Figure 3 ). The increased ventilation flow is greater than a certain threshold, and in particular greater than the nominal ventilation flow F set for the normal operation of the turbine ( Figure 2 ).

[0048] In the flow position, the closing member 40 closes the auxiliary ventilation outlet 34 to a lesser extent than in the closed position. In this case, as Figure 3 shown in, in the flow position, the closing member 40 does not close the auxiliary outlet 34 at all. For example, this can be achieved by orienting the window 42 partially or completely towards the auxiliary outlet 34, and more particularly towards the orifice 36. In this way, as Figure 3 shown in, the excess ventilation flow FF can be discharged via the auxiliary outlet 34, while the main outlet 32 can maintain its nominal outlet flow velocity dimensions.

[0049] The position of the closing member 40, and in particular the displacement of the closing member 40 between the closed position and the flow position, can be controlled by an active or passive control member. Figure 4 And Figure 5 Schematically illustrate an implementation of a passive control member according to an embodiment.

[0050] In this embodiment, the control member includes at least one profiled element 46, which is configured to drive the closing member 40 towards the flow position in the case of an increase in the ventilation flow in the ventilation cavity 30. The profiled element can be an element having an aerodynamic profile (e.g., non-zero camber) configured to generate lift. In this case, the control member includes a plurality of profiled elements 46, specifically flaps or fins in this case, which are attached to the closing member at least in the displacement direction of the closing member 40 between the closed position and the flow position. In this embodiment, the profiled element 46 receives the ventilation flow F. The generated lift causes a displacement M transverse to the ventilation flow, in this case in the circumferential direction, which tends to bring the closing member 40 to its flow position.

[0051] Furthermore, the control member may include at least one return element 50, which is configured to bias the closing member 40 to return towards the closed position. The return element 50 may be a spring, as illustrated, a tank with a compressible fluid of variable volume, an elastic element, a pair of magnets, or any other element capable of exerting a restoring force. In this case, the return element 50 has a fixed part and a movable part, the fixed part being attached here to the nozzle 28 (or another fixed part of the internal structure 22) via a stop 38, and the movable part being attached here to the closing member 40 via a stop 48. The return element 50, here a compression spring installed, tends to guide the closing member 40 to return towards the closed position.

[0052] In this way, in this embodiment, the control member includes two competing elements that tend to pull the closing member 40 to its closed position or to its flow position. These elements, specifically the return element 50 and the profiled element 46 respectively, can be dimensioned such that the balance between the two is a function of the ventilation flow in the ventilation cavity 30. In this way, in this embodiment, when the nominal ventilation flow F or a smaller flow circulates in the ventilation cavity 30, the flow is not sufficient to resist the restoring force of the compression spring to drive the profiled element 46 to rotate, so that the closing member 40 remains in Figure 4 its closed position as shown therein.

[0053] Conversely, when the ventilation flow (increased ventilation flow) FFF exceeds the threshold, the flow becomes sufficient to resist the restoring force of the return element 50 to drive the profiled element 46, and the closing member 40 moves to Figure 5 its flow position as shown therein. Then, the closing member 40 closes the auxiliary outlet 34, particularly the orifice 36, to a lesser extent, which allows the excess ventilation flow FF to flow out of the ventilation cavity 30 via the auxiliary outlet 34. As visible in Figure 5 By abutting against each other (except for the minimum length of the return element 50, if appropriate), the respective stops 38, 48 of the nozzle 28 and the closing member 40 can achieve good relative positioning of the orifice 36 and the window 42.

[0054] Therefore, the control member presented in this way achieves the subordination of the position of the closing member 40 to the intensity of the ventilation flow before the ventilation flow escapes from the ventilation cavity 30. Moreover, this embodiment enables continuous adjustment of the position of the closing member 40 according to the ventilation flow to be discharged.

[0055] In other embodiments, the position of the closing member 40 can be adjusted discretely, and the closing member 40 takes a predefined number of identified positions.

[0056] Other types of control members are possible, such as an active control member configured to drive the closure member 40 in rotation, such as an actuator, for example an actuator of the jack type. This actuator can be subordinate to a pressure sensor in the ventilation cavity 30.

[0057] A common factor of the previously described control members is that they are reversible, i.e., they allow the closure member 40 to move from the closed position to the flow position and vice versa. To the extent that the auxiliary outlet 34 is substantially provided for occasional operating points, an irreversible control member can be provided, such as a reset element configured to return the closure member 40 to its flow position, which closure member 40 is also held in this closed position by a frangible element configured to break when the pressure in the ventilation cavity 30 rises above a specific threshold.

[0058] Although the invention has been described with reference to specific embodiments, it is obvious that various modifications and changes can be made to these embodiments without departing from the general scope of the invention as defined by the claims. For example, instead of a strip configured as a loop, the closure member 40 can include one or more individual strips that can more or less block the orifice 36. The strips can slide independently of each other, for example substantially axially along the orifice 36 to block them. The auxiliary outlet 34 and the closure member 40 can have any shape, size or arrangement, as long as the closure member closes the auxiliary ventilation outlet to a greater extent in the closed position than in the flow position.

[0059] Moreover, in the case of a change in the orientation and displacement direction of the closure member, the directions presented above can of course be adapted.

[0060] According to another embodiment, even if the closed position and the flow position have been described in the case where they respectively provide 0% and 100% of the flow cross-section of the auxiliary outlet 34, the closure member 40, the auxiliary outlet 34 and / or the control member can be dimensioned such that the closed position and / or the flow position provide an intermediate flow cross-section of the auxiliary outlet 34, as long as the closure member 40 closes the auxiliary ventilation outlet 34 to a greater extent in the closed position than in the flow position.

[0061] Moreover, even if this explanation has been described in detail within the scope of a turbofan of an aircraft, the described internal structure 22 can also be applied to other types of turbines and nacelles.

[0062] More generally, the individual features of the various embodiments described above can be combined in additional embodiments. Therefore, the description and the drawings must be considered in an illustrative rather than a restrictive sense.

Claims

1. An internal structure (22) for a nacelle (18) of a turbine (10), the internal structure being intended to surround at least a part of a chamber capable of receiving a gas generator (14) of the turbine (10), the internal structure (22) comprising a ventilation cavity (30) of the chamber, the ventilation cavity (30) being provided with a main ventilation outlet (32) and an auxiliary ventilation outlet (34) separate from the main ventilation outlet (32), the internal structure (22) comprising a closing member (40), the closing member (40) comprising a strip having a window (42), the closing member (40) being movable relative to the ventilation cavity (30) between a flow position and a closed position, in the flow position, the window (42) faces at least partially the auxiliary ventilation outlet (34), and in the closed position, the closing member (40) closes the auxiliary ventilation outlet (34) to a greater extent than in the flow position.

2. The internal structure according to claim 1, wherein, The internal structure extends according to a longitudinal axis (X-X), and the auxiliary ventilation outlet (34) is axially offset relative to the main ventilation outlet (32).

3. The internal structure according to claim 1, wherein, The closing member (40) is located inside the ventilation cavity (30).

4. The internal structure according to any one of claims 1 to 3, wherein, The closing member (40) is movable in a rotational manner.

5. The internal structure according to any one of claims 1 to 3, comprising a control member configured to control the position of the closing member (40).

6. The internal structure according to claim 5, wherein, The control member comprises at least one profiled element (46) configured to drive the closing member (40) towards the flow position in the case of an increase in the ventilation flow in the ventilation cavity (30).

7. The internal structure according to claim 5, wherein, The control member comprises at least one return element (50) configured to bias the closing member (40) to return towards the closed position.

8. The internal structure according to any one of claims 1 to 3, wherein, The auxiliary ventilation outlet (34) is arranged on a side of the ventilation cavity (30) opposite to the chamber.

9. A nacelle (18) of a turbine, comprising an internal structure (22) according to any one of claims 1 to 8.

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