TURBOFAN ENGINE

Description

Technical field of the invention

[0001] The invention relates to a turbofan engine, in particular intended to equip an aircraft. Prior art

[0002] There figure 1 This illustrates a prior art turbofan engine 1, intended for use in aircraft, particularly airplanes. The turbofan engine 1 extends along an axis X and comprises, from upstream to downstream in the direction of gas flow, a fan 2, a low-pressure compressor 3, a high-pressure compressor 4, a combustion chamber 5, a high-pressure turbine 6, and a low-pressure turbine 7. The low- and high-pressure compressors 3 and 4, the combustion chamber 5, and the high- and low-pressure turbines 6 and 7 are located in a so-called primary duct 8.

[0003] A vein 9, called secondary, extending around the primary vein 8, downstream of the blower 2.

[0004] An annular row of guide vanes 10 is located at the secondary flow 9, these guide vanes 10 forming an outlet guide vane or OGV (Outlet Guide Vane). The guide vanes 10 extend radially between a radially external ferrule 11 and a housing 12 surrounding the low-pressure compressor 3.

[0005] These guide vanes 10 have the function of straightening the airflow circulating through the secondary vein 9. They can also provide a structural function.

[0006] Furthermore, in a turbofan engine, it is necessary to route equipment through the secondary duct, such as auxiliary lines, piping, a power transmission shaft, or a pylon connecting the engine to the aircraft. This equipment passes through the secondary duct downstream of the guide vanes and, to meet aerodynamic requirements, is generally enclosed in a streamlined casing. Such a casing is called a bifurcation when it extends to the downstream end of the secondary duct, or a tail in the opposite case.

[0007] Air can be drawn from the secondary duct, which carries cold air. This air is used to cool aircraft systems (cooling the air supplied to the cabin, cooling the air from the high-pressure compressor to the aircraft, etc.) or turbofan engine systems (cooling and clearance management system for the low-pressure turbine, etc.). To perform these draws, the secondary duct may include scoops. These scoops can be either flush, meaning simple openings in the surfaces defining the secondary duct, or dynamic, meaning they extend at least partially into the secondary duct. In all cases, these scoops are equipped with valves that regulate or shut off the airflow to the corresponding turbofan engine system.

[0008] These scoops are a source of pressure loss, increasing the turbofan engine's fuel consumption. Furthermore, these scoops can cause potential pressure surges from the cold side to the fan, leading to aeroelastic excitation, noise, a decrease in the fan's average efficiency, and a reduction in the pumping margin. These scoops can also generate additional noise through resonance within the scoop cavity, particularly when the corresponding valve is closed. Finally, the increased number of scoops and associated ducts increases the integration complexity and the number of parts to be manufactured and assembled within the turbofan engine.

[0009] Documents EP 2 267 273 and US 2015 / 0330309 describe turbofan engines. Presentation of the invention

[0010] The invention aims to remedy these drawbacks in a simple, reliable and inexpensive way.

[0011] To this end, the invention relates to a turbofan engine comprising a primary stream and a secondary stream surrounding the primary stream, a row of guide vanes extending in the secondary stream, downstream of a fan, at least one service extending in the secondary stream downstream of the guide vanes and housed in a profiled casing, at least one air intake scoop located at the level of the casing and equipped with a regulating valve, characterized in that at least one guide vane located near the casing has a variable geometry area and whose geometry can be adjusted in operation.

[0012] This feature allows for modification of the shape, or camber, of the relevant guide vane, thereby regulating the flow rate and controlling the nature of the flow at the scoop. This enables better adaptation to the scoop geometry and the airflow through the valve, thereby reducing noise and vibration during operation and improving the turbojet's efficiency.

[0013] The adjustment can be controlled using an actuator, such as a motor or a cylinder.

[0014] A guide vane located near the envelope is, for example, a guide vane located circumferentially within an angular range of -40° to +40° relative to the upstream end of the envelope.

[0015] The variable geometry guide vane may include at least one pivotable zone whose pivot angle can be controlled.

[0016] The area suitable for pivoting may be a downstream area of ​​said guide vane.

[0017] The envelope may include an upstream part forming, at least in part, one of the guide vanes.

[0018] Such a structure makes it possible to further improve the performance of the turbojet engine.

[0019] The scoop may open onto a surface of the casing, at an opening, said opening being located, at least partially, axially opposite the guide vanes. The scoop may open onto a surface of the casing, at an opening, said opening being located axially downstream of the guide vanes.

[0020] The scoop can open at the upstream end of the envelope.

[0021] The scoop can open onto an intrados surface or an extrados surface of the envelope.

[0022] The scoop may include an air circulation channel, said scoop including at least one fin located in said air circulation channel.

[0023] The presence of the fin improves the guidance of the airflow through the scoop. The turbojet can have one or more scoops, for the same envelope, for example one scoop opening at the level of an intrados surface and one scoop opening at the level of an extrados surface of the envelope.

[0024] The said guide vane may be located at a distance from the casing. In other words, the said guide vane, comprising at least one variable geometry zone, is offset from the casing along the axis of the turbomachine.

[0025] The invention may also include an aircraft comprising a turbojet engine of the aforementioned type. Brief description of the figures

[0026] [ Fig. 1] is a partial longitudinal cross-sectional view of a prior art turbofan engine, [ Fig. 2 ] is a schematic view of a portion of the secondary intake of a turbojet engine according to a first embodiment of the invention, [ Fig. 3 ] is a view corresponding to the figure 2 illustrating another position or geometry of the variable geometry guide vane, [ Fig. 4 ] is a schematic view of a portion of the secondary stream of a turbojet according to a second embodiment of the invention. Detailed description of the invention

[0027] THE figures 2 and 3 illustrate a part of a turbojet engine 1 according to a first embodiment of the invention.

[0028] This one differs from the classic turbojet illustrated in the figure 1 by the elements described below.

[0029] As before, the turbojet 1 has an annular primary duct 8 with axis X and an annular secondary duct 9 surrounding the primary duct 8, a row of guide vanes 10 extending in the secondary duct 9, downstream of the fan 2. At least one servicing extends in the secondary duct downstream of the guide vanes 10 and is housed in a profiled casing 13, the upstream part 14 of which forms one of the guide vanes 10.

[0030] The envelope 13 includes at least one air intake scoop 15 equipped with a regulating valve 16. The scoop is of the flush type and opens at the level of an intrados surface 17a of the envelope 13, at the level of an opening 18, said opening 18 being located, at least in part, axially opposite the guide vanes 10. The scoop supplies air to a device 19, which may be a device of the aircraft (cooling of the air intended to be delivered to the cabin, cooling of the air from the high-pressure compressor and destined for the aircraft, ...), or a device of the turbojet engine (cooling and clearance management device of the low-pressure turbine, ...).

[0031] At least one of the guide vanes 10 located on the side of the extrados surface 17a of the envelope 13 and situated close to the envelope 13 is variable geometry and its geometry can be adjusted.

[0032] In particular, said guide vane 10 includes a downstream zone 20 capable of pivoting about a pivot 21, the pivot angle being adjustable by means of an actuator, according to a calibration law that takes into account the operating conditions, for example. The calibration law may, in particular, take into account the degree of opening of the valve 16 equipping the scoop 15 or the airflow rate passing through the scoop 15.

[0033] The actuator is, for example, a motor or a cylinder.

[0034] Such a structure makes it possible to modify the shape, or camber, of the relevant guide vane 10 and thus regulate the flow rate and control the nature of the flow at the scoop 15. figures 2 and 3 thus represent two different positions of the area capable of pivoting of the relevant guiding blade 10.

[0035] There figure 2 illustrates, for example, the case where the valve 16 fitted to the scoop 15 is closed while the figure 3illustrates the case where this valve 16 is open.

[0036] There figure 4 illustrates another embodiment of the invention in which the casing 13 is separate from the guide vanes 10 and is located downstream of said vanes 10. The scoop 15 opens at its opening 18 located at the upstream end, also called the leading edge, of the casing 13.

[0037] In such a case, some of the guide vanes 10, here the two vanes closest to the opening, are variable geometry, their geometry being able to be adjusted using one or more actuators.

[0038] As before, each of these guide vanes 10 has a downstream zone 20 capable of pivoting around a pivot 21, the pivot angle being adjustable by means of an actuator, according to a calibration law that takes into account the operating conditions, for example. The calibration law may, in particular, take into account the degree of opening of the valve 16 equipping the scoop 15 or the airflow through the scoop 15.

[0039] The position shown in solid lines illustrates, for example, the case where the valve 16 equipping the scoop 15 is open, while the position shown in dotted lines illustrates the case where the valve 16 is closed.

Claims

1. A turbojet engine (1) including a primary duct (8) and a secondary duct (9) surrounding the primary duct (8), a row of guide vanes (10) extending in the secondary duct (9), downstream of a fan (2), at least one servo extending in the secondary duct (9) downstream of the guide vanes (10) and housed in a profiled casing (13), at least one air sampling scoop (15) located at the casing (13) and equipped with a regulation valve (16), characterized in that at least one guide vane (10) located proximate to the casing (13) includes a variable-geometry zone (20) and whose geometry can be adjusted during operation.

2. The turbojet engine (1) according to claim 1, characterized in that the variable-geometry guide vane (10) includes at least one pivotable zone (20) whose pivot angle can be controlled.

3. The turbojet engine (1) according to claim 2, characterized in that the pivotable zone (20) is a zone downstream of the said guide vane (10).

4. The turbojet engine (1) according to one of claims 1 to 3, characterized in that the casing (13) includes an upstream portion (14) forming, at least partially, one of the guide vanes (10).

5. The turbojet engine (1) according to one of claims 1 to 4, characterized in that the scoop (15) opens out at a surface of the casing (13), at one opening (18), said opening (18) being located, at least partially, axially opposite the guide vanes (10).

6. The turbojet engine (1) according to one of claims 1 to 4, characterized in that the scoop (15) opens out at a surface (17a, 17b) of the casing (13), at one opening (18), said opening (18) being located axially downstream of the guide vanes (10).

7. The turbojet engine (1) according to one of claims 1 to 6, characterized in that the scoop (15) opens out at the upstream end of the casing (13).

8. The turbojet engine (1) according to one of claims 1 to 6, characterized in that the scoop (15) opens out at an intrados surface (17b) or at an extrados surface (17a) of the casing (13).

9. The turbojet engine (1) according to one of claims 1 to 8, characterized in that the said guide vane (10) is located at a distance from the casing (13).

10. An aircraft including a turbojet engine (1) according to one of claims 1 to 9.