Ventilation circuit for turbomachine

Abstract

The invention relates to a ventilation circuit (80) capable of being mounted in a turbomachine (1) with a first vein (V1) with a combustion chamber (5), a second vein (V2) and equipment (90). The ventilation circuit (80) comprises a first duct (10) which connects the equipment (90) downstream to the atmosphere, a second duct (20) which connects the equipment (90) upstream to the first vein (V1) upstream of the combustion chamber (5) or to the second vein (V2) and a drive mechanism (30), and is such that in a first configuration where the turbomachine (1) is running, the air circulates in the downstream direction in the second (20) then the first (10) ducts, and in a second configuration where the turbomachine (1) is stopped, the drive mechanism (30) is running and circulates the air in the upstream direction in the first (10) then the second (20) ducts. Figure 2

Description

Title of the invention: Ventilation circuit for a turbomachine

[0001] In a turbomachine, certain equipment, for example an electrical machine or a set of parts, must be integrated into a hotter environment (a zone) of the turbomachine. In particular, such equipment is placed in an area at the rear of the turbomachine, for example in the "plug zone". Because of the expected improvements in efficiency and compactness of a turbomachine, and the proximity of the gas flow leaving the low-pressure turbine downstream of the combustion chamber, such an area tends to be increasingly hot. The present invention relates to a turbomachine in which air cooling of such equipment is necessary because this equipment can be damaged by an excessively high temperature to which it is exposed.

[0002] To cool such equipment, one solution consists of circulating around it air that is taken from a vein of the engine in which circulates air that is colder than the air that circulates in the first vein that includes the combustion chamber of the turbomachine. This vein of the engine in which circulates colder air is called "second vein". A duct connects this second vein to the equipment in order to bring the cold air to this equipment. During operation of the engine this second vein is pressurized, so that the air circulates naturally in this duct. This duct constitutes a ventilation circuit.

[0003] Thus, a ventilation circuit is known for a turbomachine with a longitudinal axis comprising a combustion chamber, a first longitudinal vein which includes the combustion chamber and a second longitudinal vein, and equipment located at the rear of the turbomachine, the ventilation circuit being capable of being mounted in the turbomachine in order to cool the equipment.

[0004] When the turbomachine is stopped, the thermal environment can remain hot, or even increase in temperature (compared to a turbomachine in operation) because of the thermal inertia of parts of the turbomachine such as the casings, and the shutdown of the ventilation. It is therefore necessary to continue to cool the equipment concerned after the turbomachine has stopped. Given that the second vein is no longer pressurized after the turbomachine has stopped, it is necessary to use an active system such as a fan in order to convey the air in the duct to the equipment to be cooled. It is therefore possible to imagine integrating such an active system into this duct and only activating it when the turbomachine is stopped.

[0005] However, to reach the equipment located in an area at the rear of the turbomachine, the conduit passes through areas of the turbomachine which are hot and which have thermal inertia (such as the primary vein). Thus, we see that in practice the equipment is heated beyond its acceptable operating temperature after the turbomachine is stopped, which is undesirable. Description of the invention

[0006] The present invention aims to remedy these drawbacks.

[0007] The invention aims to propose a ventilation circuit for a turbomachine which makes it possible to efficiently cool equipment located in an area at the rear of the turbomachine both when this turbomachine is running and when this turbomachine is stopped.

[0008] This aim is achieved by the fact that the ventilation circuit comprises a first conduit which fluidly connects the equipment downstream to the atmosphere, a second conduit which fluidly connects the equipment upstream to the first vein upstream of the combustion chamber or to the second vein, and a drive mechanism, the ventilation circuit being configured such that - in a first configuration where the turbomachine is running, the air circulates in the downstream direction in the second duct then in the first duct, and - in a second configuration where the turbomachine is stopped, the drive mechanism is running and circulates the air in the upstream direction in the first duct then in the second duct.

[0009] Thanks to these provisions, the equipment is able to be cooled satisfactorily during operation of the turbomachine, and also when this turbomachine is stopped. In addition, the use of a common duct (second duct) both when the turbomachine is running and stopped makes it possible to reduce the mass of the ventilation circuit. In addition, the air taken when the turbomachine is stopped is colder, which makes it possible to reduce the flow rate in the first duct and therefore the size of the drive mechanism.

[0010] For example, the ventilation circuit comprises a valve and a portion of the second conduit is divided into a main branch and a secondary branch provided with the drive mechanism, and such that in the first configuration the air circulates in the main branch, and in the second configuration the air circulates in the secondary branch and the valve closes the main branch.

[0011] For example, the valve is a three-way valve located at the upstream branch between the main branch and the secondary branch, and the valve closes the secondary branch in the first configuration.

[0012] For example, the valve is a butterfly valve located in the main branch.

[0013] For example, the second duct has a single branch provided with the drive mechanism and in the first configuration the drive mechanism is stopped or is running and circulates the air in the downstream direction.

[0014] For example, the turbomachine is a double-spool dual-flow turbojet engine. comprising a secondary flow vein and the second vein is the secondary flow vein and the equipment is placed radially inwardly relative to the first vein.

[0015] For example, the turbomachine is a triple-flow turbojet comprising a tertiary flow vein which surrounds the first vein, and such that the second vein is the tertiary flow vein and the equipment is placed radially internally relative to the first vein.

[0016] For example, the turbomachine is a triple-flow turbojet comprising a tertiary flow vein which surrounds the first vein and an inner casing which separates the tertiary flow vein and the first vein, and such that the second vein is the tertiary flow vein and the equipment is placed in the inner casing.

[0017] The invention also relates to a turbomachine comprising a ventilation circuit according to the invention.

[0018] The invention will be better understood and its advantages will appear better, on reading the detailed description which follows, of embodiments shown as non-limiting examples. The description refers to the appended drawings in which:

[0019] [Fig-1] [Fig.l] is a longitudinal view of a double-spool turbomachine flow.

[0020] [Fig.2] [Fig.2] is a longitudinal view of the turbomachine of [Fig.l] in in which a ventilation circuit is mounted according to one embodiment of the invention.

[0021] [Fig.3] [Fig.3] is a longitudinal view of the turbomachine of [Fig.l] in in which a ventilation circuit is mounted according to a variant of the embodiment of the invention of [Fig.2].

[0022] [Fig.4] [Fig.4] is a longitudinal view of the turbomachine of [Fig.l] in in which a ventilation circuit is mounted according to another embodiment of the invention.

[0023] [Fig.5] [Fig.5] is a longitudinal view of a three-flow propeller turbomachine.

[0024] [Fig.6] [Fig.6] is a longitudinal view of the turbomachine of [Fig.5] in in which a ventilation circuit is mounted according to one embodiment of the invention.

[0025] [Fig.7] [Fig.7] is a longitudinal view of the turbomachine of [Fig.5] in in which equipment and a ventilation circuit are mounted according to a variant of an embodiment of the invention of [Fig.6]. Detailed description of the invention

[0026] We consider a turbomachine 1 with a longitudinal axis X which is its axis of rotation. In the description below, the terms “internal” and “interior” designate an element oriented towards the longitudinal axis X or arranged closer to this axis. The terms “external” and “exterior” designate an element oriented in the opposite direction to the axis longitudinal X or arranged further from this axis. The terms "upstream" and "downstream" refer to the direction of air and gas flow during operation of the turbomachine, i.e. from left to right in the figures. The term "radial" designates a position or direction in a transverse plane perpendicular to the longitudinal axis X.

[0027] By way of example, the invention is first described in the case where the turbomachine 1 is a dual-flow double-spool turbomachine. [Fig. 1] illustrates such a turbomachine 1, in a longitudinal view. This turbomachine 1 comprises a nacelle 2 with a fan 3 comprising blades. The turbomachine 1 comprises a hub 8a, a rotating section of which carries the crown of blades forming the propeller of the fan 3. The hub 8a is made up of rotating sections and static sections alternating along the longitudinal axis X. This rotating section 8a is carried by a rotor 8 which extends along the longitudinal axis X and which is driven in rotation by a high-pressure turbine 6 and a low-pressure turbine 7, discussed below. Radially outside the hub 8a and downstream of the propeller of the fan 3 is an internal casing 8b which is coaxial with the hub 8a.

[0028] In normal operation of the turbomachine 1, an air flow (called secondary flow F2) circulates in an annular vein, called second vein V2, which extends between the inner casing 8b and the nacelle 2. Another annular vein, called first vein VI, extends between the hub 8a and the inner casing 8b. The first vein VI comprises, downstream of the fan 3, a compressor 4 and a combustion chamber 5. This compressor 4 comprises, upstream, a low-pressure compressor 4a and downstream, a high-pressure compressor 4b. The air compressed by the compressor 4 is admitted downstream into the combustion chamber 5 and mixed with fuel before being burned there. The hot gases resulting from this combustion are then expanded in a turbine in the first vein V1 and turn this turbine. This turbine comprises a high pressure turbine 6 which is located downstream of the combustion chamber 5 then a low pressure turbine 7 located downstream of the high pressure turbine 6.The high-pressure turbine 6 comprises at least one stage E and the low-pressure turbine 7 comprises several stages E, each stage E consisting of a row of fixed turbine blades, also called a nozzle, followed by a row of mobile turbine blades spaced circumferentially around the longitudinal axis X. The stages E are located in the turbine vein, which is a first vein VL The turbomachine 1 also comprises a rotor 8 whose axis of rotation is the longitudinal axis X. The mobile turbine blades of the high-pressure turbine 6 and the low-pressure turbine 7 are integral with the rotor 8. Thus, the rotation of these mobile turbine blades rotates the rotor 8 which in turn rotates the low-pressure compressor 4a, the high-pressure compressor 4b and the blades of the fan 3. The rotation of the blades of the . blower 3 contributes, with the high-speed ejection of gases leaving the combustion chamber 5, to the propulsion of the turbomachine 1.

[0029] [Fig. 2] is an enlarged view of the middle and rear part of the turbomachine 1 of [Fig. 1]. A piece of equipment 90 is located in a zone at the rear of the turbomachine 1. For example, the piece of equipment 90 is located downstream and radially inwardly relative to the low-pressure turbine 7 in the zone 91 called the “plug”. The ventilation circuit 80 is mounted in the turbomachine 1 in order to cool the piece of equipment 90. This ventilation circuit 80 comprises a first duct 10 which fluidly connects the piece of equipment 90 downstream to the atmosphere and a second duct 20 which fluidly connects the piece of equipment 90 upstream to the second vein V2. The ventilation circuit 80 further comprises a drive mechanism 30 which is capable of circulating the air in the upstream direction in the first duct 10 then in the second duct 20. For example, this drive mechanism 30 is a fan or any other element capable of circulating the air.The drive mechanism 30 comprises a control unit capable of starting and stopping the element capable of circulating the air. In the figures, the first duct 10 and the second duct 20 are shown schematically. These ducts (10, 20) are fixed to the turbomachine 1 and pass through the turbomachine in places. In particular, the second duct 20 passes through the first vein VI downstream of the combustion chamber 5, for example downstream of the low-pressure turbine 7. The first duct 10 opens into the atmosphere downstream of the radially central part and the rotor 8 of the turbomachine 1. Alternatively, the second duct 20 fluidically connects the equipment 90 upstream to the first vein VI upstream of the combustion chamber 5. Preferably, the second duct 20 opens upstream of the high-pressure compressor 4b, at a zone where the pressure and temperature are lower than in the high-pressure compressor 4b. .

[0030] The ventilation circuit 80 is configured to operate in a first configuration in which the turbomachine 1 is running. In this first configuration, the drive mechanism 30 is stopped, and the air circulates in the downstream direction in the second duct 20, this circulation occurring naturally thanks to the overpressure which exists in the second vein V2 (the pressure in the second vein is higher than the atmospheric pressure which exists at the downstream outlet of the first duct 10).

[0031] The ventilation circuit 80 is also configured to operate in a second configuration in which the turbomachine 1 is stopped. In this second configuration the drive mechanism 30 is running and circulates the air in the upstream direction in the first duct 10 then in the second duct 20. This air comes from the atmosphere downstream of the first duct 10, consequently the equipment 90 is cooled efficiently. In particular, the equipment 90 is better cooled than if the air came from upstream through the second duct 20 because the second duct 20 necessarily crosses the first vein VI which is hot (hotter than the atmosphere outside turbomachine 1) even after the turbomachine 1 has stopped, as explained above.

[0032] In the embodiment of [Fig.2] and [Fig.3], the ventilation circuit 80 comprises a valve 40 and a portion of the second conduit 20 is divided into a main branch 21 and a secondary branch 22 provided with the drive mechanism 30. In the first configuration, the air circulates in the main branch 21. In the second configuration, the valve 40 closes the main branch 21 and the air circulates only in the secondary branch 22, in order to prevent recirculation of the air downstream in this secondary branch 22.

[0033] For example, the valve 40 is a three-way valve which is located at the upstream branch between the main branch 21 and the secondary branch 22, as shown in [Fig. 2]. In the first configuration, the valve 40 closes the secondary branch 22 and the air circulates only in the main branch 21.

[0034] Alternatively, as shown in [Fig.3], the valve 40 is a butterfly valve which is located on the main branch 21. In the first configuration, the butterfly valve is open and air can therefore circulate in the secondary branch 22 in addition to circulating in the main branch 21.

[0035] In another embodiment illustrated in [Fig.4], the second duct 20 consists of a single branch which is provided with the drive mechanism 30. In other words, the second duct 20 is not divided into several branches. In the first configuration the air circulates in the second duct 20 from upstream to downstream, and in the second configuration the air circulates in the second duct 20 from downstream to upstream. In the first configuration the drive mechanism 30 is either stopped or running in order to contribute to circulating the air in the downstream direction. In this second case the drive mechanism 30 is able to operate in both directions in order to circulate the air upstream or downstream depending on the configuration. The drive mechanism control unit 30 is configured to control the drive mechanism 30 in both directions by reversing its direction of rotation.

[0036] As another example, the invention will now be described in the case where the turbomachine 1 is a three-flow turbomachine with a propeller. [Fig. 5] schematically illustrates such a turbomachine 1, in a longitudinal view. The turbomachine 1 is shown in the case of a propeller 3a of a fan 3 which is shrouded by a nacelle 2. Alternatively, the propeller 3a is unshrouded. The turbomachine 1 comprises a hub 8a, a rotating section of which carries the crown of blades forming the propeller 3a. The hub 8a is made up of rotating sections and static sections alternating along the longitudinal axis X. This rotating section 8a is carried by a rotor 8 which extends along the longitudinal axis X and which is driven in rotation by a high-pressure turbine 6 and a low-pressure turbine 7, described below. Radially outside the hub 8a and downstream of the propeller 3a of the fan 3 is an inner casing 8b which is coaxial with the hub 8a. Also downstream of the propeller 3a of the fan 3 is an outer casing 8c which surrounds the inner casing 8b. The upstream end of the outer casing 8c is upstream of the upstream end of the inner casing 8b. The nacelle 2 is located radially outside the outer casing 8c.

[0037] In normal operation of the turbomachine 1, an air flow (called secondary flow F2) circulates outside the hub 8a and the outer casing 8c. This secondary flow F2 circulates in an annular vein which extends between the outer casing 8c and the nacelle 2. Another annular vein extends between the hub 8a and the outer casing 8c then divides at the upstream end of the inner casing 8b into a first annular vein VI which extends between the hub 8a and the inner casing 8b and a second annular vein V2 which extends between the inner casing 8b and the outer casing 8c.

[0038] In the first annular vein V1 circulates a primary flow FL The first annular vein V1 comprises a compressor 4, a combustion chamber 5 located downstream of compressor 4 and a high pressure turbine 6 which is located downstream of the combustion chamber 5 then a low pressure turbine 7 located downstream of the high pressure turbine 6. The compressor 4 comprises upstream a low pressure compressor 4a and downstream a high pressure compressor 4b The blades of the compressor 4, of the high pressure turbine 6, and of the low pressure turbine 7 extend radially in the first vein VL The air compressed by the compressor 4 is admitted into the combustion chamber 5 and mixed with fuel before being burned there. The hot gases resulting from this combustion are then expanded by passing through the high pressure turbine 6 and the low pressure turbine 7 and rotate the moving blades of these turbines.The rotation of these moving turbine blades turns the rotor 8 which in turn drives the low pressure compressor 4a, the high pressure compressor 4b and the blades of the propeller 3a of the fan 3 into rotation. The rotation of the propeller 3a contributes, with the high speed ejection of the gases at the outlet of the combustion chamber 5, to the propulsion of the turbomachine 1. In the second annular vein V2 circulates a tertiary flow F3. This second vein V2 opens downstream into the atmosphere.

[0039] [Fig. 6] is an enlarged view of the middle and rear part of the turbomachine 1 of [Fig. 5]. A piece of equipment 90 is located in an area at the rear of the turbomachine 1. For example, the piece of equipment 90 is located downstream and radially internally of the low-pressure turbine 7. The ventilation circuit 80 is mounted in the turbomachine 1 in order to cool the piece of equipment 90. As in the example of the dual-flow dual-spool turbomachine described above, the ventilation circuit 80 comprises a first duct 10 which fluidly connects the piece of equipment 90 downstream to the atmosphere and a second duct 20 which fluidly connects the piece of equipment 90 upstream to the second vein V2. The ventilation circuit 80 further comprises a drive mechanism 30 which is capable of circulating the air in the upstream direction in the first duct 10 then in the second duct 20. For example, this drive mechanism 30 is a fan or any other element capable of circulating the air. The drive mechanism 30 comprises a control unit capable of starting and stopping the element capable of circulating the air. In the figures, the first duct 10 and the second duct 20 are shown schematically. These ducts (10, 20) are fixed to the turbomachine 1 and pass through the turbomachine in places. In particular, the second duct 20, the drive mechanism 30 and, where appropriate, the valve 40 are located in the internal casing 8b. The second duct 20 passes through the first vein VI downstream of the combustion chamber 5, for example downstream of the low-pressure turbine 7.The first duct 10 opens into the atmosphere downstream of the radially central part and the rotor 8 of the turbomachine 1.

[0040] The ventilation circuit 80 is configured to operate in a first configuration and in a second configuration, as already described above in the example of the dual-flow twin-spool turbomachine. The advantage provided by the ventilation circuit 80 according to the invention is particularly relevant when the turbomachine 1 comprises an air-oil exchanger 9 which is located in the second vein V2. This air-oil exchanger 9 is located longitudinally between the low-pressure compressor 4a and the high-pressure compressor 4b and radially externally relative to these compressors (4a, 4b). The air-oil exchanger 9 heats the air passing through it, and consequently the temperature of the air in the second vein V2 downstream of the air-oil exchanger 9 is higher than in the absence of this air-oil exchanger 9, hence the advantage of the ventilation circuit 80 according to the invention.

[0041] Alternatively, as shown in [Fig.7] which is an enlarged view of the rear part of a turbomachine 1 such as that shown in [Fig.5], the equipment 90 is also located in an area at the rear of the turbomachine 1 but in the inner casing 8b. In this case the second duct 20, the drive mechanism 30 and, where appropriate, the valve 40 are located in the inner casing 8b. The first duct 10 opens into the atmosphere downstream of the inner casing 8b. In this alternative, the second duct 20 does not pass through the first vein VI, however it passes through the downstream part of the inner casing 8b which is at a high temperature during operation of the turbomachine 1 and after its shutdown. This configuration justifies taking air from the atmosphere through the first duct 10 to cool the equipment 90 more effectively.

[0042] In the embodiment of [Fig.6] and [Fig.7], the ventilation circuit 80 comprises a valve 40 and a portion of the second conduit 20 is divided into a main branch 21 and a secondary branch 22 provided with the drive mechanism 30. Alternatively, the second conduit 20 consists of a single branch which is provided with the drive mechanism 30.

Claims

Claims

1. Ventilation circuit (80) for a turbomachine (1) with a longitudinal axis (X) comprising a combustion chamber (5), a first longitudinal vein (VI) which includes said combustion chamber (5) and a second longitudinal vein (V2), and equipment (90) located at the rear of said turbomachine (1), said ventilation circuit (80) being capable of being mounted in said turbomachine (1) in order to cool said equipment (90), said ventilation circuit (80) being characterized in that it comprises a first duct (10) which fluidically connects downstream said equipment (90) to the atmosphere, a second duct (20) which fluidically connects upstream said equipment (90) to said first vein (VI) upstream of the combustion chamber (5) or to said second vein (V2), and a drive mechanism (30), said ventilation circuit (80) being configured such that - in a first configuration where said turbomachine (1) is in operation,the air circulates in the downstream direction in said second duct (20) then in said first duct (10), and - in a second configuration where said turbomachine (1) is stopped, said drive mechanism (30) is running and circulates the air in the upstream direction in said first duct (10) then in said second duct (20).,

2. A ventilation circuit (80) according to claim 1 such that said ventilation circuit (80) further comprises a valve (40) and a portion of said second conduit (20) is divided into a main branch (21) and a secondary branch (22) provided with said drive mechanism (30), and such that in said first configuration air circulates in said main branch (21), and in said second configuration air circulates in said secondary branch (22) and said valve (40) closes said main branch (21).

3. Ventilation circuit (80) according to claim 2 such that said valve (40) is a three-way valve located at the upstream branch between said main branch (21) and said secondary branch (22), and said valve (40) closes said secondary branch (22) in said first configuration.

4. Ventilation circuit (80) according to claim 2 such that said valve (40) is a butterfly valve located in said main branch (21).

5. A ventilation circuit (80) according to claim 1 such that the second conduit (20) has a single branch provided with said drive mechanism (30) and such that in the first configuration said drive mechanism (30) is stopped or is running and circulates the air in the downstream direction.

6. Ventilation circuit (80) according to any one of claims 1 to 5 such that said turbomachine (1) is a double-spool double-flow turbojet comprising a secondary flow vein (F2) and said second vein (V2) is said secondary flow vein (F2) and said equipment (90) is placed radially internally relative to said first vein (VI).

7. Ventilation circuit (80) according to any one of claims 1 to 5 such that said turbomachine (1) is a triple-flow turbojet comprising a tertiary flow vein (F3) which surrounds said first vein (VI), and such that said second vein (V2) is the tertiary flow vein (F3) and said equipment (90) is placed radially internally relative to said first vein (VI).

8. Ventilation circuit (80) according to any one of claims 1 to 5 such that said turbomachine (1) is a triple-flow turbojet comprising a tertiary flow vein (F3) which surrounds said first vein (VI) and an internal casing (8b) which separates said tertiary flow vein (F3) and said first vein (VI), and such that said second vein (V2) is said tertiary flow vein (F3) and said equipment (90) is placed in said internal casing (8b).

9. Turbomachine (1) comprising a ventilation circuit (80) according to any one of the preceding claims.

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