Retention device for a cooling tube for a turbomachine casing

Abstract

A retention device for at least one cooling tube of a cooling system of a turbomachine casing, the casing extending around an axial direction of the turbomachine, the retention device includes a fixing plate suited to being made integral with the casing and a retention element for the cooling tube. The retention device includes an adjustment system configured to adjust the relative position of the retention element with respect to the fixing plate and to absorb a relative movement between the retention element and the fixing plate.

Claims

1. A retention device for at least one cooling tube of a cooling system of a turbomachine casing, the casing extending around an axial direction of the turbomachine, the retention device comprising a fixing plate configured to being made integral with the casing and a retention element for the cooling tube, said retention device comprising an adjustment system configured to adjust a relative position of said retention element with respect to said fixing plate and to absorb a relative movement between the retention element and the fixing plate.

2. The retention device for at least one cooling tube of a cooling system of a turbomachine casing according to claim 1, wherein said fixing plate comprises an opening and wherein said adjustment system comprises a body integral with said retention element, said body being translationally moveable through said opening.

3. The retention device for at least one cooling tube of a cooling system of a turbomachine casing according to claim 2, wherein said body is a cylindrical body having a threaded portion.

4. The retention device for at least one cooling tube of a cooling system of a turbomachine casing according to claim 3, wherein said adjustment system comprises a screwing element cooperating with said threaded portion of said body to adjust the relative position of said retention element with respect to said fixing plate.

5. The retention device for at least one cooling tube of a cooling system of a turbomachine casing according to claim 4, wherein the screwing element is a self-locking nut.

6. The retention device for at least one cooling tube of a cooling system of a turbomachine casing according to claim 1, wherein said adjustment system comprises an elastic return element to absorb a relative movement between the retention element and the fixing plate.

7. The retention device for at least one cooling tube of a cooling system of a turbomachine casing according to claim 1, wherein said retention element is configured to be arranged in integral contact with a radially outer part of said at least one cooling tube.

8. The retention device for at least one cooling tube of a cooling system of a turbomachine casing according to claim 1, wherein said retention element is configured to be arranged in integral contact with two cooling tubes.

9. The retention device for a cooling tube of a cooling system of a turbomachine casing according to claim 1, wherein said opening has a shape allowing a displacement of said retention element in a plane orthogonal to an axis of the opening of said fixing plate.

10. The retention device for a cooling tube of a cooling system of a turbomachine casing according to claim 1, wherein said opening has an oblong shape.

11. A cooling system of a turbomachine casing comprising: a cooling tube; a retention device for at least one cooling tube according to claim 1, said cooling tube being made integral with said retention device by brazing.

12. The cooling system of a turbomachine casing according to claim 11, further comprising a plurality of cooling tubes, a plurality of retention devices, each retention device of said plurality ensuring the simultaneous retention and adjustment of the position of two adjacent cooling tubes.

13. A casing for a turbomachine low pressure turbine comprising a cooling system according to claim 11 arranged in a radially outer manner with respect to the casing.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The figures are only presented for illustrative purposes and in no way limit the invention.

(2) FIG. 1a illustrates a first perspective view of a cooling system for a turbomachine casing according to the prior art.

(3) FIG. 1b illustrates a second perspective view of the cooling system for a turbomachine casing illustrated in FIG. 1a.

(4) FIG. 2 is a partial sectional view of an exemplary embodiment of cooling system by air jets according to the invention mounted around a turbine casing.

(5) Unless stated otherwise, a same element appearing in the different figures has a single reference.

DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT OF THE INVENTION

(6) FIGS. 1a and 1b have already been described previously as technological background.

(7) FIG. 2 is a partial sectional view of an exemplary embodiment of a cooling system 100 by air jets according to the invention mounted around a turbomachine turbine casing 10. In the exemplary embodiment represented in FIG. 2, the casing 10 is a low pressure turbine casing.

(8) The cooling system 100 according to the invention comprises: a plurality of cooling tubes 120 (only two adjacent tubes are represented in FIG. 2) mounted around the casing 10; a retention device 101 for the cooling tubes 120 for the positioning and the retention of the cooling tubes 120 around the casing 10.

(9) The cooling system 100 in the example represented is a LPTACC (Low Pressure Turbine Active Clearance Control) cooling device. With typically two supply boxes, not represented in FIG. 2, the cooling tubes 120 and the retention device 101 constitute the cooling system 100 of the low pressure turbine casing 10. Such a system could also apply to a LPTCC cooling device without going beyond the scope of the invention.

(10) Conventionally, the two cooling tubes 120 have small openings, not visible in FIG. 2. In operation, the supply boxes supply with air relatively fresh with respect to the casing 10 the cooling tubes 120, which send to the outer face 11 of the casing 10 the air thus available through small openings (not visible in the figure). Typically, the two supply boxes are arranged in a diametrically opposite manner on the casing 10. Thus, each zone of the cooling tubes 120 is supplied with air by a supply box arranged at less than a quarter turn of the casing 10, which makes it possible to have a sufficient air flow rate sent via the small openings of the cooling tubes 120 whatever the considered zone of the cooling tubes 120.

(11) The retention device 101 notably comprises a fixing plate 104 having a main part 105, a first end 106 and a second end (not represented). The fixing plate 104 is made integral on the casing 10 through intermediate panels 107 integral with the ends of said fixing plate 104. The fixing plate 104 is integral with the intermediate panels 107 for example by riveting or instead by bolting.

(12) The casing 10 has a body 13 and lateral edges 14 (a single edge being represented in FIG. 2). Each intermediate panel 105 is made integral on the casing 10 at the level of the lateral edges 14 of the casing 10, for example by riveting or by bolting.

(13) The main part 105 of the fixing plate 104 has an outer face 118, an inner face 119, and at least one through opening 108. The main part 105 of the fixing plate 104 may comprise a portion or a plurality of portions, for example with recesses as illustrated in the document FR1258238. Each portion is globally flat and extends over the totality of the width of the main part 105 and two consecutive portions form an angle such that the main wall 104 thus follows the general shape of the casing 10 thanks to its different portions and to the angles that they form between each other and/or with each of the two ends.

(14) The retention device 101 comprises an adjustment means making it possible to adjust the relative position of the cooling tubes 120 with respect to the fixing plate 104 and to absorb relative movements between the cooling tubes 120 and the fixing plate 104. The adjustment means comprise a body 150 traversing said at least one opening 108. The body 150 is for example of cylindrical shape. The body 150 is translationally movable through said opening 108 and more precisely along a direction transversal to the plane formed by the opening 108 or by the portion on which the opening 108 is provided. The relative position of the body 150 with respect to the fixing plate 108 is adjustable via a screwing element 183 detailed hereafter.

(15) The body 150 of cylindrical shape has a first end 151 and a second end 152. The second end 152 is integral with a retention element 160 enabling the engagement of at least one cooling tube 120. The retention element 160 is for example a preformed retention plate.

(16) According to the exemplary embodiment illustrated in FIG. 2, the retention plate 160 is for example obtained by forming and has a globally flat central part 161 and two ends 162, 163 of half-ring shape intended to hug and to cover, at least partially, the annular shape of two adjacent cooling tubes 120. The cooling tubes 120 are made integral on the retention plate 160 for example by brazing. The retention plate 160 advantageously makes it possible to make the cooling tubes integral at the level of a radially outer part of the cooling tubes, that is to say on the fixing plate 104 side, notably in such a way as to avoid the presence of a part or an additional element between the cooling tube 120 and the casing 10, and so as to be able to bring even closer the cooling tubes 120 to the casing 10 for the optimisation of the cooling thereof.

(17) Advantageously, the retention plate 160 covers at least partially the circumference of the cooling tubes and uniquely a radially outer part of the cooling tubes 120, notably the circumference of the cooling tubes facing the fixing plate 104.

(18) Advantageously, the retention plate 160, such as represented, makes it possible to make integral two cooling tubes 120 by means of a same and unique retention plate 160. In this embodiment, a retention and a positioning of two circumferentially adjacent cooling tubes is achieved by forming uniquely one opening 108 in the fixing plate 104. Thus, for a given turbomachine with a given number of cooling tubes, the fixing plate 104 according to the invention will have less opening 108 and less engagement zone than a fixing plate according to the prior art. However, it is also envisaged to produce a retention element making it possible to make integral individually a cooling tube so as to improve the precision of adjustment of the radial position of the cooling tubes 120 with respect to the casing 10.

(19) According to the exemplary embodiment illustrated in FIG. 2, the second end 152 of the cylindrical body 150 has a cylindrical cup 153 of which the axis of revolution is oriented along the longitudinal axis of the cylindrical body 150. The cylindrical cup 153 is for example made integral with the cylindrical body 150 by brazing.

(20) The cylindrical cup 153 notably makes it possible to form a bearing element and to create a sufficient contact surface for brazing of the retention element 160.

(21) On the other hand, the cylindrical cup 153 forms a bearing element for a return spring 170. In the exemplary embodiment illustrated in FIG. 2, the return spring 170 is a compression spring mounted under the fixing plate and more precisely between the cylindrical cup 153 of the second end 152 of the cylindrical body 150 and the inner face 119 of the fixing plate 104. A first washer 181 is intercalated between the return spring 170 and the inner face 119 of the fixing plate 104. Thus, the return spring 170 is directly bearing on the first washer 181 and not on the fixing plate 104, notably to avoid phenomena of wear.

(22) The return spring 170 is an elastic element participating in the adjustment of the position of the cylindrical body 150, and thus of the retention element 160 for the cooling tubes 120 and making it possible to absorb the relative movements between the cooling tubes 120 and the fixing plate 104, the relative movements notably originating from differential expansions between the different elements of the cooling system and the casing 10. The return spring 170 also makes it possible to absorb the vibrations of the turbomachine, thus avoiding breakage of the cooling system in operation.

(23) At the level of the outer face 118 of the fixing plate 104, a screwing element 183, such as a nut, cooperates with a threaded portion of the cylindrical body 150 provided for example at the level of the first end 151 of the body 150. The screwing element 183 has a locking means making it possible to avoid any rotation thereof under the effect of vibrations. The screwing element 183 is for example a self-locking nut.

(24) The return spring 170, the nut 183 cooperating with the threaded part of the body 150 form the adjustment means of the retention device 101 making it possible to modify the position of the retention element 160 and the cooling tubes with respect to the fixing plate 104, and with respect to the casing 10.

(25) Advantageously, a second washer 182 is intercalated between the nut 183 and the outer face 118 of the fixing plate 104, such that the base of the nut 183 is in contact with the second washer 182 and not directly with the fixing plate 104, notably to avoid phenomena of wear.

(26) Said at least one opening 108 provided in the fixing plate 104 is advantageously an opening of oblong shape thus allowing displacements of the cylindrical body 150, and the retention element 160, in a plane orthogonal to the axis of the opening 108 in such a way as to allow differential expansions of the cooling tubes 120 with respect to the casing 10 during operation.

(27) Thus, thanks to the retention device according to the invention, it is possible to modify precisely the relative position of the retention element 160, and thus the cooling tubes 120, with respect to the casing 10 by a simple rotation of the nut 183. In the case where the threading provided on the first end 151 of the cylindrical body has a right-handed thread, then the screwing of the nut 183 causes a moving away of the cooling tubes 120 from the casing 10, the clearance J between the cooling tubes 120 and the casing 10 is then increased. Conversely, the unscrewing of the nut 183 causes a bringing closer of the cooling tubes 120 to the casing 10, the clearance J between the cooling tubes 120 and the casing 10 is then reduced. The return spring 170 makes it possible to exert a constant thrust on the retention element 160 in such a way that the nut 183 is constantly bearing on the washer 182, notably to guarantee correct positioning of the cooling tubes 120.

(28) The retention device 101 according to the invention thus makes it possible to achieve a precise, simple, efficient adjustment by controlling the clearance J between the casing 10 and each cooling tube 120 or group of several cooling tubes 120 (for example two cooling tubes as represented in FIG. 2) by the elimination of a fixing collar entirely surrounding the cooling tube. Thus, the retention device according to the invention makes it possible to guarantee controlled positioning of the cooling tubes 120 with respect to the casing 10 in an individual manner (that is to say tube by tube) or in a grouped manner (by group of several cooling tubes). Thanks to the invention, the positioning of the cooling tubes 120 is controlled which makes it possible to improve cooling of the casing while minimising the risks of contact between the cooling tubes 120 and the casing 10 and thus the wear of the casing 10.