Turbomachine distributor comprising a thermal protection sheet with a radial stop, and associated thermal protection sheet

Abstract

A distributor of a turbomachine configured to be mounted in a housing, including: a plurality of segments; a plurality of anti-rotation pins, mounted both on a segment of the distributor and on the housing; and a thermal protection sheet, including at least one axial tab configured to radially abut against an inner face of a first anti-rotation pin, and at least one radial tab configured to axially abut against an upstream face of a second anti-rotation pin.

Claims

1. A distributor for a turbomachine, or a low-pressure distributor, to be mounted in a housing, comprising: a plurality of segments circumferentially distributed around an axis of rotation of the turbomachine; a plurality of anti-rotation pins, each of which is mounted both on a segment of the distributor and on the housing; and a thermal protection metal sheet, positioned between the housing and the segments of the distributor, comprising a plurality of tabs, each tab bearing against an anti-rotation pin; wherein the plurality of tabs of the thermal protection metal sheet comprises at least one axial tab radially abutting against a radially inward face of a first anti-rotation pin, and at least one radial tab axially abutting against an upstream face of a second anti-rotation pin.

2. The distributor according to claim 1, wherein the thermal protection metal sheet comprises a plurality of the axial tabs and the radial tabs.

3. The distributor according to claim 1, wherein the number of the radial tabs and the number of the axial tabs is equal.

4. The distributor according to claim 1, wherein the radial tabs and the axial tabs alternate along the thermal protection metal sheet, around the axis of rotation of the turbomachine, and are separated by an indentation, or with removal of material.

5. The distributor according to claim 1, wherein the at least one axial tab is at a distance from the first anti-rotation pin when the turbomachine is at rest.

Description

(1) Other features, objects and advantages of the present invention will become better apparent upon reading the detailed description which follows, made with reference to the appended figures given as non-limiting figures and wherein:

(2) FIG. 1 is a partial axial sectional view of a turbine distributor mounted in a housing of a turbomachine according to the prior art,

(3) FIG. 2 is a partial axial sectional view of an exemplary turbine distributor mounted in a housing of a turbomachine according to the invention,

(4) FIG. 3a is a perspective view of an exemplary thermal protection metal sheet according to the invention,

(5) FIG. 3b is a detailed view of a portion of the thermal protection metal sheet of FIG. 3a,

(6) FIG. 4a is a first perspective view of the example of FIG. 2,

(7) FIG. 4b is a second perspective view of the example of FIG. 2, and

(8) FIG. 5 illustrates an exemplary turbomachine onto which the invention is applied.

(9) The invention will now be most particularly described with reference to a low pressure distributor 2 of a turbomachine 1, mounted on a housing 3 of a low-pressure turbine 7.

(10) A low pressure distributor 2 is formed that with fixed blades positioned on a wheel divided into a plurality of segments 20, circumferentially distributed around an axis of rotation X of the turbomachine 1. Each segment 20 comprises several fixed adjacent blades secured to a ring sector element, as well as an upstream retention means and a downstream retention means. These retention means are for example annular rails 32, 24 made in an internal wall 30 of the housing 3 upon which supporting surfaces 22, 24 will bear, made on the ring sectors of the segments 20 of a distributor 2 as described above.

(11) In order to block the sectors in rotation, the distributor 2 comprises a plurality of devices for blocking the segments, each comprising an anti-rotation pin 40, mounted both on a segment 20 of the distributor 2 and on the turbine housing 3. Similarly to what is described in document FR 2 960 951, a protrusion on the upstream face of each segment 20 comprises an indentation in which is accommodated the anti-rotation pin 40. This pin 40 comprises a head 41 accommodated in the indentation and a rod 42 slipped into a radial bore of the wall 30 of the housing 3, and thereby prevents any movement of rotation of the distributor segment 20 around the axis of the latter (corresponding to the axis of rotation X of the turbomachine).

(12) A thermal protection metal sheet 10 is interposed between the segments 20 of the low pressure distributor 2 and the internal wall 30 of the turbine housing 3, and adapted for limiting the heat radiation from the distributor 2 on the turbine housing 3. This thermal protection metal sheet 10, upstream, bears against a radial surface portion 33 made in the internal wall of the housing. Conventionally, the upstream edge 12 of the protection sheet 10 is radially curved inwards so as to form a hairpin. Optionally, the upstream edge may further bear upon an upstream edge of the segment 20 of the distributor 2 and participate in maintaining the latter against the upstream rail 32 of the housing 3.

(13) Downstream, the thermal protection metal sheet 10 comprises a plurality of tabs 14, 16, each being adapted to bear against an anti-rotation pin 40 of the blocking devices.

(14) In order to limit the risks of “fretting” generated by the contact between the thermal protection metal sheet 10 and the housing 3, the metal sheet 10 is modified at its downstream portion. Indeed, the thermal protection metal sheet 10 comprises tabs 14, 16 adapted so that the metal sheet radially abuts and axially abuts against the anti-rotation pins 40. The thermal protection metal sheet is therefore maintained in position against the anti-rotation pins 40, while is displacement is limited in the direction of the internal wall 30 of the housing 3. Here, by radial direction will be meant a direction extending substantially transversely with respect to the axis X of the turbomachine, and by axial direction will be meant a direction extending substantially parallel to the axis X of the turbomachine.

(15) For example, the tabs 14, 16 of the thermal protection 10 may comprise axial tabs 14, adapted to radially abut against the corresponding anti-rotation pin 40, and radial tabs 16, adapted to axially abut against the corresponding anti-rotation pin 40.

(16) Thus, the radial tabs 16 extends transversely with respect to the axis X of the turbomachine 1, and give the possibility of maintaining in an axial position the thermal protection metal sheet 10 with respect to the distributor 2. These radial tabs 16 therefore form axial stops. For this, the radial tabs 16 are for example laid out to extend facing an upstream face 46 of the anti-rotation pins 40, this upstream face 46 corresponding to the face of the anti-rotation pins directed towards the upstream side of the turbomachine 1, facing the gas flow.

(17) The axial tabs 14, as for them, substantially extend parallel to the axis X of the turbomachine 1, and give the possibility of preventing the thermal protection metal sheet 10 from moving towards the turbine housing 3, i.e. along a radial direction. This is why these axial tabs form radial stops. The axial tabs 14 are for example laid out to extend facing a lower face 44 of the anti-rotation pins 40, this lower face 44 corresponding to the face of the anti-rotation pins 40 directed towards the axis of rotation X of the turbomachine 1, facing the distributor 2.

(18) According to an embodiment, the thermal protection metal sheet 10 substantially comprises as many axial tabs 14 as there are radial tabs 16. Thus, if the distributor 2 comprises twenty-six anti-rotation pins 40, the thermal protection metal sheet 10 may for example comprise thirteen axial tabs 14 and thirteen radial tabs 16.

(19) The radial tabs 16 and the axial tabs 14 may moreover be distributed in alternation along the periphery of the thermal protection metal sheet 10, in order to observe the symmetry of the turbomachine 1 and to balance the distributor 2.

(20) The thermal protection metal sheet 10 is preferably ring-shaped, and may be in one piece, i.e. in a single part, or obtained by association of several annular segments connected together.

(21) The tabs 14, 16 may be formed integrally with the remainder of the thermal protection metal sheet 10. For example they may be obtained by cutting the downstream edge of the thermal protection metal sheet 10 to form indentations 18, with or without removal of material. In the embodiment illustrated in FIGS. 1 to 4b, the indentations 18 are made with removal of material, in order to avoid possible friction of the axial tabs 14 against the anti-rotation pin 40 upon thermal expansion of the distributor 2.

(22) Further, the thermal protection metal sheet 10 may comprise one tab 14, 16 per anti-rotation pin 40, so that for a given anti-rotation pin 40, the thermal protection metal sheet 10 has opposite either a radial tab 16, or an axial tab 14. Alternatively, the thermal protection metal sheet 10 may comprise one radial tab 16 and one axial tab 14 per anti-rotation pin 40. A same anti-rotation pin 40 may then be found in radially abutting against an axial tab 14 and axially abutting against a radial tab 16.

(23) The axial tabs 14 may be wider (along the circumference of the thermal protection metal sheet 10) than the radial tabs 16. For example, a circumferential width of an axial tab 14 may correspond to the distance separating three adjacent anti-rotation pins 40. A given axial tab 14 may therefore not only extend facing the corresponding anti-rotation pin 40, but also on either side of this pin 40 as far as the adjacent anti-rotation pins 40, the adjacent anti-rotation pins 40 each being found facing another tab preferably a radial tab 16. This embodiment actually gives the possibility of simplifying the making of the thermal protection metal sheet 10, of reinforcing the resistance to radial forces of the axial tab 14 applied by the anti-rotation pin 40, and of avoiding contact of the metal sheet 10 with the turbine housing 3 in spite of the vibrations to which the latter is subject, and also gives the possibility of obtaining better protection against heat radiation.

(24) The radial tabs 16, as for them, then have a width (along the circumference of the thermal protection metal sheet 10) substantially corresponding to the width of the upstream face 46 facing the anti-rotation pin 40.

(25) Alternatively, the radial tabs 16 are the ones which are wider than these axial tabs 14, and they extend between three adjacent anti-rotation pins 40, the axial tabs 14 then being of a width substantially equal to the width of the lower face 44 facing the anti-rotation pin 40.

(26) According to another further alternative, the axial tabs 14 and the radial tabs 16 are of equal width and extend on either side of each anti-rotation pin 40, over a width globally equal to the distance between two adjacent anti-rotation pins 40.

(27) Optionally, the radial tabs 16 may be introduced into a groove made in the face facing the corresponding anti-rotation pin 40.

(28) Moreover, in the rest position, i.e. when the turbomachine 1 is not operating, the axial tabs 14 may extend facing the lower face 44 of the corresponding anti-rotation pins 40 and at a distance therefrom in order to allow a determined radial displacement of the thermal protection metal sheet 10 in the event of thermal expansion of the latter. This radial displacement is however limited, the axial tab 14 forming a radial stop when it comes into contact with the lower face 44 of the anti-rotation pin. Therefore there exists a space 19 between the axial tabs 14 and the lower surface 44 of anti-rotation pins 40, when the distributor 2 is at rest.

(29) On the other hand, the radial tabs 16 are in contact with the upstream face 46 of the anti-rotation pins 40, regardless of whether the turbomachine 1 is at rest or operating, in order to maintain the thermal protection metal sheet 10 in position with respect to the distributor 2 and to the turbine housing 3.