AIR JET COOLING DEVICE FOR A TURBINE HOUSING AND TURBOMACHINE CONTAINING SUCH A DEVICE

Abstract

The invention relates to an air jet cooling device (100) for a turbine housing (48), in particular a low-pressure turbine housing (28), comprising at least one air supply housing (120), at least one cooling manifold (110) intended to be arranged around the housing to be cooled, each cooling manifold or manifold comprising two cooling tubes (112) arranged on either side of said housing, the supply housing (120) comprising two side walls (125, 126), each side wall comprising air outlet ports (127), each port having a main axis and being configured and dimensioned to receive one of the associated cooling tubes, the cooling device comprising a fastening system for fixing the cooling tubes to said housing,characterized in that each cooling tube is integral with said fastening system and movable in translation along the principal axis (P) within the associated orifice. Figure for the abbreviation: Figure 6,

Description

Title of the invention: AIR JETS COOLING DEVICE FOR A TURBINE HOUSING AND TURBOMACHINE COMPRISING SUCH A DEVICE Technical field

[0001] The invention relates to an air jet cooling device for the casing of a low-pressure turbine, for example, a turbomachine. The invention also relates to a turbomachine equipped with such a cooling device.

[0002] The invention has applications in the field of aeronautics and, in particular, in the field of cooling an aircraft turbine casing. Prior art

[0003] In the field of aeronautics, the stator of a low-pressure turbine in a turbomachine consists primarily of a casing that must be cooled. One cooling technique uses impact cooling technology. For this purpose, the casing is equipped with one or more pressurized air supply units, each of these units being connected to cooling ducts that surround the casing and distribute the cooling air over its entire periphery.

[0004] Fig. 1 represents a partial longitudinal cross-sectional view of a turbine 28A of a turbomachine 10A surrounded by a casing 48A cooled by a cooling device 100A.

[0005] Figure 2 shows a perspective view of such a 100A device. Air jet cooling of the crankcase, according to the prior art, in which the turbine is not shown for the sake of simplicity. This cooling device 100A conventionally comprises one or more cooling rails 110A connected to at least one air distribution box 120A. In the example of [Fig. 2], eight cooling rails 110A are shown, each connected between two air distribution boxes 120A, positioned approximately 180° apart. Each cooling rail 110A has two tubes 112A extending parallel to each other around the crankcase for approximately 180°. Each tube of each cooling rail 110A has a series of holes opening at the outer surface of the crankcase. The pressurized air passing through these holes provides impact ventilation of the crankcase.Each 112A cooling tube features a drilling pattern that allows the crankcase to be cooled at numerous points in order to control the clearance between the moving wheels and the turbine housing and thus optimize engine efficiency.

[0006] Each air distribution box 120A includes an air inlet compartment 122A connected to external ducts 130A through which air circulates to cool various parts of the turbomachine. The air inlet compartment 122A ensures the transfer of cooling air between the external ducts 130A and the air distribution box 120A.

[0007] In a known manner, the cooling tubes 112A are assembled and held in place by ramp supports 140A using mounting clamps 142A configured to hold the cooling tubes 112A in position on the ramp supports 140A. [Fig. 3] illustrates a cross-sectional view of such a ramp support and the clamps. [Fig. 4] shows a perspective view of such a clamp.

[0008] The 140A ramp supports are fixed to the housing by flanges and configured to maintain the tubes spaced apart. More specifically, the 140 ramp supports are adapted to maintain a constant air gap between an air outlet in a tube and the outer surface of the housing regardless of the temperature, i.e., whether the turbine is stopped or running.

[0009] The cooling tubes 112A are mounted in the mounting brackets 142A so as to be able to slide within the brackets. The mounting brackets 142A generally consist of a layer of metal surrounded by two layers of a braided silica sheath coated with polytetrafluoroethylene (PTFE), which protects the cooling tube 112A from metal-on-metal friction and ensures optimal tube sliding within the bracket.

[0010] However, during maintenance, damage to the cooling tubes was observed due to friction between the tubes and clamps. In fact, during operation, the PTFE in the clamp sheath tends to melt due to the radiant heat from the upper low-pressure turbine housing (350°C), which corresponds to the maximum operating temperature of PTFE. Once the PTFE is no longer in contact, the silica braid degrades through abrasion, resulting in metal-to-metal contact between the clamp reinforcement and the cooling tube. This contact wears down the cooling tube, sometimes to the point of perforation.

[0011] To date, there is no material for the fixing collar that can protect the cooling tube from any contact with the silica sheath of the collar and is resistant to temperatures exceeding the radiant heat of the low pressure turbine housing at a "reasonable" price.

[0012] The objective of the present invention is to overcome at least some of the problems mentioned above. In particular, the present invention provides a solution for ensuring the mechanical strength of the cooling ramps while guaranteeing the integrity of the cooling tubes that constitute them. Summary of the invention

[0013] To this end, the invention relates to an air jet cooling device for a turbine casing, in particular a low-pressure turbine, comprising at least one air supply box, at least one cooling ramp intended to be arranged around the casing to be cooled, the cooling ramp or each cooling ramp comprising two cooling tubes arranged on either side of said box, the supply box comprising two side walls, each side wall comprising air outlet orifices, each orifice having a main axis and being configured and dimensioned to receive one of the associated cooling tubes, the cooling device comprising a fastening system intended to fix the cooling tubes to said casing, characterized in that each cooling tube is integral with said fastening system and movable in translation along the main axis in the associated orifice.

[0014] Thus, the invention proposes to secure the cooling tubes to the clamps of the ramp supports, thereby preventing wear in this area. The tangential movements of the cooling tubes are then managed at the level of the air distribution box(es) by allowing the cooling tubes to slide at their connection with the air distribution box(es).

[0015] Such a cooling device according to the invention makes it possible to avoid removing engines for maintenance, particularly of this device, and thereby minimizes engine maintenance time thanks to the improved mechanical strength of the cooling tubes in their clamps. The invention improves engine robustness by eliminating the degradation of the interface between the cooling tubes and their mounting clamps due to friction, as well as the degradation of radial clearances in the turbine, particularly at low pressure, during operation.

[0016] The cooling device according to the invention may include one or more of the following features, taken individually or in combination with each other in all technically possible combinations: - each side wall of the power supply housing has at least one smooth socket arranged in one of said air outlet orifices, each smooth socket being configured and sized to receive one of the associated cooling tubes; - each socket of at least one smooth socket has an inner cylindrical wall with axis the main axis of the associated air outlet orifice, the inner cylindrical wall having an annular groove housing a sealing element; - the sealing element is a gasket, preferably an O-ring; - each smooth socket is a single piece with said side wall; - the fixing system includes at least two supports for at least one ramp intended to be fixed to the casing, each ramp support including at least one fixing collar for one of the tubes of the same ramp, the tube being fixed securely to the fixing collar, for example by brazing, welding or gluing; - the device includes at least two cooling ramps and in which each support of the fixing system is shaped to keep said ramps spaced apart from each other; - each cooling tube is curved and designed to be arranged around a part of the crankcase to be cooled and at a distance from it, and includes several openings leading into the crankcase.

[0017] The invention also relates to a turbine, in particular a low-pressure turbine, comprising a casing and equipped with an air jet cooling device according to the invention and described above.

[0018] The invention also relates to a turbomachine, in particular an aircraft turbomachine, comprising such a turbine or comprising a casing and equipped with an air jet cooling device according to the invention and as described above. Brief description of the drawings

[0019] The present invention will be better understood and other details, features and advantages of the present invention will become more apparent upon reading the description of a non-limiting example that follows, with reference to the accompanying drawings in which: - Fig. 1, already described, is a schematic partial longitudinal cross-section view of a turbine of a turbomachine; - the [Fig.2], already described, is a schematic perspective view of an air jet cooling device for the crankcase 120, according to the prior art; - the [Fig.3], already described, represents a schematic longitudinal cross-sectional view of a system for fixing the ramps of a cooling device on a casing according to the prior art; - the [Fig.4], already described, is a schematic perspective view of a retaining collar for a ramp of the fixing system of the [Fig.3]; - [Fig.5] is a schematic partial cross-sectional view of a turbomachine equipped with a turbine casing cooling device according to the invention; - [Fig.6] represents a partial schematic perspective view of an air jet cooling device for the crankcase according to the invention; - [Fig. 7] is an enlarged cross-sectional view of the connection area of ​​a cooling rail on a distribution box of the cooling device in [Fig. 6]; and - [Fig.8] schematically represents a view from below of a ramp support of the cooling device of [Fig.6].

[0020] An example of an embodiment of an air jet cooling device for a low-pressure turbine housing is described in detail below, with reference to the accompanying drawings. This example illustrates the features and advantages of the invention. It should be noted, however, that the invention is not limited to this example.

[0021] In the figures, which are shown by way of illustration and in no way limit the invention, identical elements are identified by identical reference numerals. For the sake of legibility, the size scales between the represented elements are not to scale. Description of the implementation methods

[0022] Reference is first made to [Fig. 5], which schematically represents a twin-spool, twin-flow aircraft turbomachine 10 to which the invention applies. Of course, the invention can be applied to other types of turbomachines equipped with an electric motor, for example a turboprop, without departing from the scope of the invention.

[0023] The turbomachine 10 has a longitudinal axis denoted C around which its various components extend.

[0024] The turbomachine 10 conventionally comprises a gas generator 12 upstream of which is arranged a blower 14. The blower 14 is surrounded by a blower housing 16 which is surrounded by a nacelle 18 which extends around and along a major part of the gas generator 12.

[0025] The gas generator 12 here comprises two bodies, namely a low-pressure body 12a or BP and a high-pressure body 12b or HP. Each body comprises a compressor and a turbine.

[0026] In the present invention, and generally, the terms "upstream" and "downstream" are defined with respect to a main direction F of fluid flow inside the turbomachine, and here along the longitudinal axis C, i.e. from left to right with reference to [Fig.1].

[0027] From upstream to downstream, the gas generator 12 comprises a low pressure compressor 20, a high pressure compressor 22, a combustion chamber 24, a high pressure turbine 26 and a low pressure turbine 28.

[0028] The longitudinal axis C is the axis of rotation of the moving elements of the turbomachine 10, and in particular, of the turbines 26, 28.

[0029] The fan 14 comprises an annular row of blades 30 driven in rotation by a fan shaft 32 which is connected to the rotor of the low-pressure body 12a via a reduction gear 33. The gas flow through the fan (arrow F) is separated upstream of the gas generator 12 by an annular nozzle 34 into an internal radially annular flow, called the primary flow 36 which supplies the gas generator 12, and into an external radially annular flow, called the secondary flow 38 which flows between the gas generator 12 and the nacelle 18 and provides most of the thrust of the turbomachine.

[0030] In the description, the terms "internal" or "inside" and "external" or "outside" are used by way of non-limiting agreement with reference to the radial distance from the longitudinal axis C around which the turbomachine extends, the term "internal" defining an area radially closer to the longitudinal axis of the nacelle, as opposed to the term "external". Furthermore, in the description and the claims, the terminology axial, radial, and transverse shall be adopted by way of non-limiting agreement with reference to the trihedral axis A, R, T shown in the figures, the axial axis A being parallel to the longitudinal axis C of the turbomachine.

[0031] An inlet housing 40 structurally connects the gas generator 12 to the fan housing 16 and the nacelle 18. The inlet housing 40 comprises an annular row of radially internal arms 42 extending into the primary flow 36, and an annular row of radially external stator blades 44 (of the OGV type) extending into the secondary flow 38. The arms 42 are generally limited in number (fewer than ten) and are tubular and traversed by auxiliary passages. The number of blades 44 (OGV) is generally greater than ten.

[0032] Furthermore, each turbine, and in particular the low-pressure turbine 28, is surrounded by a casing 48 cooled by a cooling device 100 according to the invention and as will be described in detail below. The casing 48 is generally flared from upstream to downstream and substantially frustoconical in shape. It comprises an outer surface 21, an upstream end, and a downstream end.

[0033] Fig. 6 represents a perspective view of such a 100 air jet cooling device for the crankcase, according to the invention, a view in which neither the turbine nor its crankcase are shown for the sake of simplification.

[0034] The cooling device 100 comprises, as described in the technological background, at least one air outlet 110, also called a cooling manifold, connected to at least one air distribution box 120. In the example of [Fig. 6], ten cooling manifolds 110 are shown, each connected to at least one air distribution box 120. Preferably, each manifold is connected to two air distribution boxes 120 positioned at approximately 180° to each other as illustrated in [Fig.2]. The two cases are similar or even identical.

[0035] The air distribution box 120, hereinafter referred to simply as the box, includes an air inlet compartment (not visible in [Fig. 6]) connected to the external ducts of the turbomachine, through which air circulates to cool various parts of said turbomachine as illustrated in [Fig. 2]. The air inlet compartment ensures the transfer of cooling air from the external ducts to the interior of the air distribution box 120 and to the cooling ducts 110.

[0036] The air distribution housing 120 further comprises a closed enclosure 124, enclosed tangentially by first and second lateral walls 125, 126, which are said to be opposite because they face each other. The first and second lateral walls 125, 126 form an angle with each other, the apex of which is upstream of the air distribution housing 120. In other words, the tangential distance between the first and second lateral walls 125, 126 increases from upstream to downstream. In other words, the enclosure 124 of the housing flares outwards from upstream to downstream.

[0037] In order to allow the fixing of the air distribution housing 120 on the casing, said housing 120 has, mounted on the enclosure 124, fixing tabs 121. These fixing tabs can be fixed by any known means (welding, glue, etc.) on the outer surface of the enclosure 124 of the air distribution housing 120, on the one hand, and on the casing, on the other hand.

[0038] Each cooling rail 110 comprises two cooling tubes 112 arranged on either side of the housing 120 and extending over approximately 180°. The cooling tubes 112 have a preferably circular cross-section and are curved in an arc shape, conforming to the external shape of the housing 48. The cooling tubes 112 of the different rails extend parallel to each other along half a circumference of the housing. Each tube 112 is pierced with a series of small orifices opening onto an external surface of the housing 48 to provide impact ventilation of said housing. The pressurized air passing through these orifices provides impact ventilation of the housing 48.Each tube 112 is connected, at one end, to the first side wall 125 of one of the air distribution boxes 120 and, at the other end, to the second side wall 126 of the other air distribution box. Of course, if the cooling device 100 has only one air distribution box 120, the first end of the tubes 112 is connected to the first side wall 125 of the air distribution box 120 and the second end of the tubes 112 is connected to the second side wall 126 of the same air distribution box 120. Furthermore, if the cooling device 100 has more than two boxes 120... air distribution, for example n boxes, then n cooling tubes 112 will be connected each between two of the n consecutive air distribution boxes.

[0039] Thus, in the example of [Fig. 6], the first side wall 125 of the air distribution housing 120 is adapted to receive each of the tubes 112 of the cooling rails 110. Similarly, the second side wall 126 of the air distribution housing 120 is adapted to receive each of the tubes 112 of the cooling rails 110. For this purpose, as shown in Figures 6 and 7, each of the side walls 125, 126 has as many air outlet ports 127, or circular ports, as there are tubes 112 of the cooling rails 110. Each port 127 has a main axis P (illustrated in [Fig. 7]) and is configured and dimensioned to receive one of the associated cooling tubes 112.

[0040] In addition, one of the side walls 125, 126 of the air distribution housing 120 is adapted to receive the air inlet compartment.

[0041] Furthermore, the cooling device 100 includes a fastening system 140 for securing the cooling tubes to said housing. The fastening system 140 for the cooling rails to the turbine housing of a turbomachine, particularly a low-pressure turbine, is designed to prevent variations in the air gap between said rails and the outer wall of the housing, even when hot, i.e., during turbine operation, and more specifically, to maintain a constant air gap between an air outlet in a tube and the outer surface of the housing regardless of the temperature, i.e., whether the turbine is stopped or running. To this end, the fastening system 140 includes at least one rail support 141. Figure 8 schematically shows a "bottom view" of such a rail support, i.e., in a radial direction from the inside out.The support(s) is / are configured to maintain the ramps spaced apart from each other, along the axial direction A of the housing 48. The ramp supports 141 are fixed to the housing in a known manner by flanges. Each ramp support 141 has at least one retaining clamp 142 for one of the cooling tubes 112. Each retaining clamp 142 is configured to hold the cooling tubes 112 in position on the ramp supports 141.

[0042] According to the invention, and contrary to the prior art, each cooling tube 112 of the cooling ramps 110 is integral with the fixing system and more specifically with the fixing collars 142. Preferably, each cooling tube 112 is fixed integrally to the fixing collar 142 by brazing, welding or gluing.

[0043] Such a fastening system thus makes it possible to ensure the mechanical strength of the cooling ramps while guaranteeing the integrity of the cooling tubes that support them They constitute. Indeed, such a fastening system prevents wear on the cooling tubes 112 and the clamps in their contact area.

[0044] According to the invention, the tangential movements of the cooling tubes 112 are managed at the level of the air distribution box(es) 120. To this end, each cooling tube 112 is movably connected relative to the distribution box 120. More precisely, each cooling tube 112 is translationally movable along the principal axis P within the associated orifice 127 of a lateral wall 125, 126 of the box. Thus, such an arrangement allows the cooling tubes 124 to slide at their connection with the air distribution box(es) 120.

[0045] Preferably, each tube 112 is connected to one of the circular openings 127 in a side wall via a smooth cylindrical sleeve 150 arranged in one of the air outlet openings 127. Each sleeve 150 is configured and sized to receive one of the associated cooling tubes. Therefore, the sleeve 150 has a cross-section adapted to the cross-section of the associated cooling tube 112, preferably circular.

[0046] Each bushing 150 is a single piece with said side wall, for example by brazing or bonding. Each bushing 150 comprises a cylindrical body 152 having an inner cylindrical wall 154 with axis to the main axis P of the associated air outlet 127. In the example illustrated in [Fig. 7], the cylindrical body 152 is brazed to a side wall of the housing via a contact surface 153 between the two elements. Alternatively, the cylindrical body 152 has an outer cylindrical wall coaxial with the inner cylindrical wall 154, the outer cylindrical wall of each bushing 150 being brazed into one of the circular orifices 127 of a side wall 125, 126 of the housing 120.

[0047] Advantageously, the inner cylindrical wall 154 has an annular groove 156 housing a sealing element 158 ​​such as a gasket ensuring the seal of the connection, preferably an O-ring. Furthermore, the housing is devoid of a stop at the end of the cooling tube 112 on the housing 120 side to allow easy replacement of the gasket in case of wear.

[0048] Although described through a number of examples, variations, and embodiments, the cooling device according to the invention includes various variations, modifications, and improvements that will be obvious to those skilled in the art, it being understood that these variations, modifications, and improvements form part of the scope of the invention. For example, a cooling ramp may consist of a single annular tube extending over an angular sector of approximately 360° or of more than two juxtaposed tubes forming a sector total angular range of approximately 360° and connected to each other by an air distribution box.

Claims

Demands

1. An air jet cooling device (100) for a turbine housing (48), particularly a low-pressure turbine housing (28), comprising at least one air supply housing (120), at least one cooling rail (110) for arrangement around the housing to be cooled, the cooling rail or rails comprising two cooling tubes (112) arranged on either side of said housing, the supply housing (120) comprising two side walls (125, 126), each side wall comprising air outlet ports (127), each port having a principal axis and being configured and dimensioned to receive one of the associated cooling tubes, the cooling device comprising a fastening system for securing the cooling tubes to said housing, each side wall (125, 126) of the supply housing comprising at least one smooth bushing (150) arranged in one of said outlet ports air,each smooth sleeve (150) being configured and dimensioned to receive one of the associated cooling tubes (112), characterized in that each cooling tube is integral with said fastening system and movable in translation about the principal axis (P) in the associated orifice and each sleeve (150) of at least one smooth sleeve comprises an inner cylindrical wall (154) with axis the principal axis of the associated air outlet orifice (127), the inner cylindrical wall comprising an annular groove (156) housing a sealing element (158).

2. Device according to claim 1, wherein the sealing element (158) is a seal, preferably an O-ring.

3. Device according to any one of claims 1 or 2, wherein each smooth socket is one piece with said side wall.

4. Device according to any one of the preceding claims, wherein the fastening system comprises at least two supports for at least one ramp intended to be fixed to the housing, each ramp support comprising at least one fixing collar for one of the tubes of the same ramp, the tube being fixed securely to the fixing collar, for example by brazing, welding or gluing.

5. Device according to claim 4, comprising at least two cooling ramps and wherein each support of the system The fixing system is designed to keep the said ramps spaced apart from each other.

6. A device according to any one of the preceding claims, wherein each cooling tube (112) is curved and intended to be arranged around and at a distance from a portion of the housing to be cooled and comprising several orifices opening into the housing.

7. Turbine, in particular a low-pressure turbine, comprising a casing and equipped with an air-jet cooling device (100) according to any one of the preceding claims.

8. Turbomachine, in particular aircraft turbomachine, comprising a turbine, in particular a low-pressure turbine, according to claim 7 or comprising a casing and equipped with an air-jet cooling device (100) according to any one of claims 1 to 6.

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