Device for cooling an annular outer turbine casing

Abstract

A device (26) for cooling an annular outer turbine casing (17) includes at least one circumferentially extending tube (27) having an air inlet intended for conveying cooling air, the tube having a radially inner wall provided with cooling air discharge openings and a radially outer wall arranged radially opposite each other, an air inlet manifold (28), the inlet of the tube opening into the manifold, the tube (27) including at least one intermediate wall extending over a circumferential portion of the tube from the air inlet, the intermediate wall being located radially between the radially inner wall and the radially outer wall, the radially inner wall and the intermediate wall forming a first air conveying duct, the radially outer wall and the intermediate wall forming a second air conveying duct extending circumferentially beyond the first air conveying duct, relative to the air inlet.

Claims

1. A device for cooling an annular outer turbine casing, the device comprising: at least one tube extending circumferentially around the annular outer turbine casing and having an air inlet intended for conveying cooling air, the at least one tube having a radially inner wall provided with cooling air discharge openings and a radially outer wall arranged radially opposite the radially inner wall, an air inlet manifold, the air inlet of the at least one tube opening into the air inlet manifold, characterized in that the at least one tube comprises an intermediate wall extending over a circumferential portion of the at least one tube from the air inlet of the at least one tube, the intermediate wall being located radially between the radially inner wall and the radially outer wall, the radially inner wall and the intermediate wall forming a first air conveying duct, the radially outer wall and the intermediate wall forming a second air conveying duct extending circumferentially, from the air inlet of the at least one tube to beyond the first air conveying duct, wherein the intermediate wall has a first end through which it is connected to the air inlet manifold, and a second end circumferentially remote from the first end, the second end joining the radially inner wall, wherein the device comprises at least two tubes, each tube being axially offset from each other tube, the air inlet of each of the at least one tube opening into the air inlet manifold.

2. The device according to claim 1, wherein the intermediate wall extends circumferentially over an angle between 0 and 45° from the air inlet, the radially inner wall and the radially outer wall each extending at an angle between 0 and 90° from the air inlet.

3. The device according to claim 2, wherein a cross-section of the at least one tube decreases with a circumferential position relative to the air inlet.

4. The device according to claim 2, wherein a cross-section of the at least one tube and the first air conveying duct and the second air conveying duct is substantially square or rectangular.

5. The device according to claim 2, characterized in that the first air conveying duct and the second air conveying duct are additively manufactured with the at least one tube.

6. The device according to claim 1, wherein a cross-section of the at least one tube decreases with a circumferential position relative to the air inlet.

7. The device according to claim 6, wherein a cross-section of the at least one tube and the first air conveying duct and the second air conveying duct is substantially square or rectangular.

8. The device according to claim 6, characterized in that the first air conveying duct and the second air conveying duct are additively manufactured with the at least one tube.

9. The device according to claim 1, wherein a cross-section of the at least one tube and the first air conveying duct and the second air conveying duct is substantially square or rectangular.

10. The device according to claim 9, characterized in that the first air conveying duct and the second air conveying duct are additively manufactured with the at least one tube.

11. The device according to claim 1, characterized in that the first air conveying duct and the second air conveying duct are additively manufactured with the at least one tube.

12. The device according to claim 1, comprising at least two tubes extending circumferentially opposite each other, the air inlet of each at least one tube opening into the air inlet manifold.

13. A turbine assembly, comprising: the annular outer turbine casing according to claim 1; and the device for cooling the annular outer turbine casing according to claim 1, located radially outside the annular outer turbine casing, the air discharge openings being oriented towards the annular outer turbine casing.

14. A turbine for a turbomachine, having an assembly comprising: the annular outer turbine casing according to claim 1; and the device according to claim 1 for cooling the annular outer turbine casing located radially outside the annular outer turbine casing, the air discharge openings being oriented towards the annular outer turbine casing.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The invention will be better understood and other details, characteristics and advantages of the invention will appear when reading the following description, which is given as a non-limiting example, with reference to the appended drawings.

(2) FIG. 1 is a cross-sectional schematic view of a turbomachine.

(3) FIG. 2 is a detailed cross-sectional schematic view of a portion of a low or high pressure turbine.

(4) FIG. 3 is a schematic view, of an annular outer turbine casing of the prior art.

(5) FIGS. 4-6 are cross-sectional views of a tube of the device, according to planes 4-4, 5-5, 6-6 of FIG. 3.

(6) FIG. 7 is a perspective top view of an annular outer turbine casing cooling device according to the invention.

(7) FIG. 8 is a cross-sectional view of the cooling device according to the invention.

(8) FIGS. 9-12 are cross-sectional views of a tube of the device, according to planes 9-9, 10-10, 11-11 and 12-12 of FIG. 8 respectively.

(9) FIG. 13 is a view corresponding to FIG. 7, illustrating an alternative embodiment of the invention.

DETAILED DESCRIPTION

(10) In the detailed description, the elements of the turbomachine 1 cited in reference to FIGS. 1 and 2 keep the same numerical references.

(11) FIGS. 7 to 12 show a cooling device 26 for an outer casing 17 according to one embodiment of the invention.

(12) The device 26 comprises several circumferentially extending tubes 27 connected to each other by a cooling air inlet manifold 28. Air enters tangentially or circumferentially into the manifold 28, through the inlet 27a, then the air from the manifold 28 enters tangentially or circumferentially into the tubes 27. The cooling device 26 is positioned radially outside the annular outer casing 17 of the turbine, in this case a low-pressure turbine 7.

(13) For example, the cooling air is taken from the outlet of the low-pressure compressor 3 or high-pressure compressor 4. The cooling air has a relatively lower temperature than the temperature of the exhaust gases from the combustion chamber 5, which pass through the high pressure turbine 6 and the low pressure turbine 7. The temperature of the cooling air, for example, is between 200 and 300° C.

(14) The tubes 27, sixteen in number in the example shown, are divided into two pairs of eight tubes axially offset from each other along the X axis. The two pairs of tubes 27 extend circumferentially opposite each other, each on one side of the air inlet manifold 28.

(15) The tubes 27 of the same pair are held together on at least one axially extending arm 29, three arms 29 in the illustrated embodiment. Each arm 29 is stationary relative to the annular outer casing 17.

(16) Each tube 27 includes a first end 30 forming an air inlet opening into the air inlet manifold 28, and a second end 31 circumferentially opposite the air inlet. Each tube 27 is closed at its second end 31.

(17) Each tube 27 comprises a radially inner wall 32, located opposite the annular outer casing 17, and a radially outer wall 33. Said walls 32, 33 are positioned radially opposite each other. The radially inner wall 32 and the radially outer wall 33 are connected to each other by two radially extending side walls 34.

(18) The radially inner wall 32 is provided with discharge openings 35 allowing cooling air to pass from the inside of the concerned tube 27 to the outside. In particular, the cooling air is discharged from the tube 27 through the discharge openings 35 towards the annular outer casing 17, in order to cool it.

(19) Each tube 27 also includes an intermediate wall 36 extending over a circumferential portion of the tube 27 from the air inlet 30. The intermediate wall 36 is located radially between the radially inner wall 32 and the radially outer wall 33. The intermediate wall 36 has a first end 37 through which it is connected to the air inlet manifold 28, and a second end 38 circumferentially remote from the first end 37, the second end 38 joining the radially inner wall 32. The intermediate wall 36 also extends between the two side walls 34.

(20) A first air duct 39 is delimited by the radially inner wall 32, the intermediate wall 36 and the side walls 34. A second air duct 40 is delimited by the radially outer wall 33, the intermediate wall 36 and the side walls 34.

(21) Each duct 39, 40 has a square or rectangular section.

(22) The first duct 39 and the intermediate wall 36 extend from the air inlet 30 to an angle α1 taken in a plane perpendicular to the axial direction of the turbomachine between 0 and 45°.

(23) The second duct 40 and the tube 27 extend from an air inlet 30 to an angle α2 taken in a plane perpendicular to the axial direction of the turbomachine between 45 and 90°.

(24) The first circumferential zone 41 is defined as the zone between the air inlet 30 of the tube 27 and the junction zone between the intermediate wall 36 and the radially inner wall 32, i.e. extending between 0° and α1

(25) A second circumferential zone 42 is defined as the zone between the junction zone between the intermediate wall 36 and the radially inner wall 32 and the second end 31 of the tube 27, i.e. extending between α1 and α2

(26) The second duct 40 is located radially outside the first duct 39 in the first circumferential zone 41.

(27) As shown in FIG. 8, the cross-section of the second duct 40 in the second circumferential zone 42 decreases with the angular position relative to the air inlet 30. In other words, in the second circumferential zone 42, the cross-section of the second duct 40 is larger at the angle α1 than at the angle α2.

(28) FIGS. 9 to 12 illustrate sections of a tube 27 of the cooling device 26, respectively according to planes 9-9, 10-10, 11-11 and 12-12 shown in FIG. 8.

(29) In FIGS. 9 to 11, the sections are rectangular, with the longest sides of the sections extending radially.

(30) Sections 9-9 and 10-10, in FIGS. 9 and 10 respectively, illustrate the two ducts 39, 40, each duct 39, 40 having a substantially square cross-section. Section 11-11, in FIG. 11, located between α1 and α2, corresponds only to the second duct 40, the section plane 11-11 being located closer to the angle α1 than to the angle α2.

(31) Finally, in FIG. 12, the tube 27 has a substantially square cross-section, the section plane 12-12 being located between α1 and α2, closer to the angle α2 than to the angle α1.

(32) In operation, the cooling air from the manifold 28 enters each tube 27 through its air inlet 30. The cooling air is then conveyed through each duct 39, 40 so that it is discharged from the tubes 27 through the discharge openings 35 in the radially lower wall 32. In particular, in this embodiment, air enters tangentially or circumferentially into the manifold 28, through the inlet 27a, then the air from the manifold 28 enters tangentially or circumferentially into the tubes 27.

(33) The air discharged through the openings 35 then impacts the annular outer casing 17 of the low-pressure turbine 7 in order to cool it.

(34) The presence of the first duct 39 radially inside the second duct 40 ensures thermal insulation of the cooling air circulating in the first circumferential zone 41 of the second duct 40.

(35) Thus, the air discharged from tube 27 in the second circumferential zone 42 maintains a relatively low temperature, which allows a homogeneous cooling over the entire circumference of the outer casing 17.

(36) FIG. 13 illustrates an alternative embodiment that differs from the one shown above in that the air inlet 27a of the manifold 28 is directed radially so that air enters radially from the outside inwards into the manifold 28 before entering the tubes 27. Such an embodiment makes it possible to limit pressure drops within the manifold. This improves cooling efficiency.