EP1911934B1 - Blade of a turbomachine - Google Patents

Description

The invention relates to a mobile turbine engine blade. It is intended for any type of turbomachine: turbojet, turboprop, gas turbine land ...

More particularly, the invention relates to a blade without a heel. A dawn is said without a heel when it does not have a platform at its upper end.

Known examples of blades without heel are described in the documents US 2002/0182074 A1 , US 2004/0096328 A1 , EP 1650404 A2 and US 2004/0179940 A1 .

The Figures 1 to 3 represent a mobile blade without heel, of known type, mounted on the rotor disc of a turbine (or a compressor) turbojet.

This known blade 8 comprises a fixing foot 10 surmounted by a blade 12, this blade having an end face 14 and side faces of the lower surface 16 and the upper surface 18, the fixing foot 10 and the said face of the blade. end 14 being respectively located at the lower and upper ends of the blade, opposite in the main direction A of the blade, the blade 12 having on its upper edge of a lower surface, a projecting edge 20 defined between a portion 24 of its face 14 and an upper portion 22 of its intrados face 16, these portions 22, 24 forming between them an average edge angle B. This average edge angle is calculated by averaging the edge angles measured at different points of the edge, between the parts 22, 24, each angle being measured in a plane perpendicular to the tangent to the edge at the point considered. On the figure 2 for the sake of simplification, it was considered that the edge angle between the parts 22 and 24, measured in the plane of the figure 2 , was equal to the average edge angle B.

The turbojet engine comprises a rotor disk 26 with a rotation axis R, the blades 8 are distributed circumferentially around the disk 26 and extend radially outwardly from this disk. The main direction A of each blade 8 corresponds to a direction radial with respect to the axis R. The blades 8 are surrounded externally by a housing ring 28, an interstice I (see figure 2 ) remaining between the end face 14 of the blade and this ring 28.

Upstream and downstream are defined in the present application with respect to the flow direction of the air flow F flowing through the turbojet engine. F1 and F2 are the respective components of the flux F in a plane perpendicular to the main direction A, such as the section plane III-III of the figure 3 , and in a plane parallel to the main direction A, as the section plane II-II of the figure 2 .

Downstream of the projecting edge 20 a zone of turbulence C is created in the stream F (see FIG. figure 2 ). The flow F to cross the gap I must bypass the edge 20 and the turbulence zone C. To qualify this phenomenon, it is called detachment of the flux F at the edge.

It is generally sought to promote as much as possible the detachment of the flux F in the gap I because the more this separation is important, the greater the effective cross section of the flow F in the gap I is reduced and therefore the proportion of the flow F crossing the gap is reduced. However, the flow F crossing the gap I does not participate in the performance of the turbojet engine. By favoring the separation, the efficiency of the turbojet engine is improved and, consequently, the fuel consumption of the latter is reduced.

To promote delamination, it is known to choose the average edge angle B strictly less than 90 °, as shown in FIGS. Figures 1 to 3 or in examples of vanes known and described in FR 05 04811 and US 6,672,829 .

The invention aims to further promote the detachment of the flux at the edge.

To achieve this object, the subject of the invention is a turbomachine mobile blade, without heel, comprising a fixing foot surmounted by a blade, this blade having an end face and lateral faces of the lower and upper surfaces. , the fixing foot and said end face being respectively located at the lower and upper ends of the blade, opposite along the main axis of the blade, the blade having on its upper edge of a lower surface, a defined projecting edge between a portion of its end face and an upper portion of its underside face, these portions forming between them an average edge angle strictly less than 90 °, so as to promote delamination, at the edge , of the flow of fluid passing through the turbomachine, characterized in that the upper part of the intrados face is corrugated and follows, in any plane section perpendicular to the main direction of the blade, a contour line fo rmée by a succession of curves alternately concave and convex.

In the present application, a curve is considered concave when its curved portion is oriented towards the upper surface of the blade. Conversely, a curve is considered convex when its curved portion is oriented opposite the extrados face of the blade.

Thus, said intrados face has curved zones defined by the stacking of said convex curves along the main direction of the blade, and recessed zones defined by the stacking of said concave curves along the main direction of the blade.

Thus, said contour line has an alternation of weakly and strongly inclined segments with respect to the components of the fluid flow in said section plane (under normal operating conditions of the turbomachine), and said upper part of the intrados wall. dawn has weakly and strongly inclined zones with respect to the flow, these zones being defined by the stacking of said weakly and strongly inclined segments, along the main direction of the blade.

The said slightly inclined zones guide the flow towards the strongly inclined zones. In this way, the flow passes mainly by the strongly inclined zones, before crossing said edge. However, for the flow passing through the steeply inclined zones, the edge angle to be crossed (ie the stop angle "seen" from the flow) is lower than if said upper part was smooth (ie without ripples). . As the delamination is all the more important as the edge angle to be crossed by the flow is small, better delamination is obtained with said corrugated upper part than with a smooth part. This reduces the losses of flow in the interstice I.

Advantageously, said slightly inclined segments are oriented according to the components of the flow in the section plane (under normal operating conditions of the turbomachine), so that they form with these components an angle close to 0 °. In this way, the flow does not pass through the slightly inclined zones before crossing said ridge (it does not "see" them) and passes almost exclusively through the highly inclined zones.

Advantageously, said strongly inclined segments are oriented transversely with respect to the components of the flow in the section plane (under normal operating conditions of the turbomachine), so that they form with these components an angle close to 90 °. It is according to this orientation that the edge angle to be crossed by the flow is the lowest and therefore that the separation of the flow in the gap is the most important. In other words, the delamination is most important when the steeply inclined areas face the components of the fluid flow in said section plane.

• la figure 1 est une vue en perspective d'une partie d'un turboréacteur équipé d'une aube de type connu;
• la figure 2 représente l'aube de la figure 1 en section suivant le plan II-II, plan perpendiculaire à la tangente à l'arête de l'aube, passant par le point D;
• la figure 3 représente l'aube de la figure 1 en section suivant le plan III-III, plan perpendiculaire à la direction principale A de l'aube, coupant la partie supérieure de la face d'intrados de l'aube, et passant par le point D;
• la figure 4 est une vue en perspective d'une partie d'un turboréacteur équipé d'un premier exemple d'aube selon l'invention;
• la figure 5 représente l'aube de la figure 4 en section suivant le plan V-V, plan perpendiculaire à la tangente à l'arête de l'aube, passant par le point D;
• la figure 6 représente l'aube de la figure 4 en section suivant le plan VI-VI, plan perpendiculaire à la direction principale A de l'aube, coupant la partie supérieure ondulée de la face d'intrados de l'aube et passant par le point D;
• la figure 7 est une section analogue à celle de la figure 6, représentant un deuxième exemple d'aube selon l'invention;
• la figure 8 est une section analogue à celle de la figure 5, représentant un troisième exemple d'aube selon l'invention;
• la figure 9 est une section analogue à celle de la figure 5, représentant en section suivant le plan IX-IX un quatrième exemple d'aube selon l'invention;
• la figure 10 est une section analogue à celle de la figure 6, et représente en section suivant le plan X-X, l'exemple d'aube de la figure 9; et
• la figure 11 est une section analogue à celle de la figure 5, représentant un cinquième exemple d'aube selon l'invention.

The invention and its advantages will be better understood on reading the detailed description which follows. This description refers to the appended figures in which:

• the figure 1 is a perspective view of a portion of a turbojet engine equipped with a blade of known type;
• the figure 2 represents the dawn of the figure 1 in section along the plane II-II, plane perpendicular to the tangent at the edge of the blade, passing through the point D;
• the figure 3 represents the dawn of the figure 1 in section along the plane III-III, plane perpendicular to the principal direction A of the dawn, intersecting the upper part of the intrados face of the blade, and passing through the point D;
• the figure 4 is a perspective view of a portion of a turbojet engine equipped with a first example of blade according to the invention;
• the figure 5 represents the dawn of the figure 4 in section along the plane VV, plane perpendicular to the tangent at the edge of the blade, passing through the point D;
• the figure 6 represents the dawn of the figure 4 in section along the plane VI-VI, plane perpendicular to the principal direction A of the dawn, intersecting the undulating upper part of the intrados face of the blade and passing through the point D;
• the figure 7 is a section similar to that of the figure 6 , representing a second example of blade according to the invention;
• the figure 8 is a section similar to that of the figure 5 , representing a third example of blade according to the invention;
• the figure 9 is a section similar to that of the figure 5 , representing in section according to plan IX-IX a fourth example of blade according to the invention;
• the figure 10 is a section similar to that of the figure 6 , and represents in section according to the XX plane, the dawn example of the figure 9 ; and
• the figure 11 is a section similar to that of the figure 5 , representing a fifth example of blade according to the invention.

The Figures 1 to 3 have been described above.

With reference to Figures 4 to 6 a first example of blade 108 according to the invention will be described. Similar elements between this dawn 108 and that of Figures 1 to 3 are identified by the same numerical references increased by 100.

The blade 108 differs from the blade 8 with respect to the upper portion 122 of its intrados wall 116.

The blade 108 comprises a fixing foot 110 surmounted by a blade 112, this blade having an end face 114 and side faces of the lower surface 116 and the upper surface 118. The attachment foot 110 and the face of the blade end 114 are respectively located at the lower and upper ends of the blade 108, opposite in the main direction A of the blade. The blade 112 has on its upper edge of a lower surface a protruding edge 120 defined between a portion 124 of the end face 114 and an upper portion 122 of the intrados face 116. The portions 122 and 124 form an angle between them. of average edge B strictly less than 90 °.

According to the invention, the upper part 122 of the intrados face is corrugated so that it follows, in any plane section perpendicular to the main direction A of the blade and, in particular, in the section plane VI-VI, a contour line 130 formed by a succession of alternately concave curves 129 and convex 131. Thus, this contour line 130 has an alternation of weakly 130a and strongly 130b segments inclined relative to the F1 components of the stream F in the plane of section considered, here the plane VI-VI.

Slightly inclined segments 130b are rather oriented along the F1 components of the flow in the section plane VI-VI, whereas the strongly inclined segments 130a are oriented transversely with respect to the F1 components of the flow in this plane. In this way, the stream F passes almost exclusively along the steep segments 130a before crossing the gap I. As the strongly inclined segments 130a face the flow F (more precisely the F1 components of this flow), the separation of the flux F at the edge 120 is improved, compared with the separation obtained in the example of the Figures 1 to 3 .

In the example of Figures 4 to 6 , the blade 108 comprises at its upper end an open cavity 132 defined by a bottom wall 134, a lower edge 136 and an extrados edge 138. Said protruding edge 120 is formed on the underside flange 136 between the end face of this flange (which corresponds to said end face portion 124) and the underside face of this rim (which belongs to said upper portion 122 of the intrados face 116).

It will also be noted that, according to this example, the blade comprises an internal cooling passage 142 and at least one cooling channel 140 communicating with this cooling passage 142.

Advantageously, the channel 140 opens on said end-face portion 124, at the level of the curved undulating zones of the upper part 122 of the intrados face, that is to say at the level of the convex curves 131 of the contour line 130 (see figure 6 ). It is indeed in these curved areas that there is the most material and it is therefore easier to achieve (for example by drilling) the channel 140.

With reference to the figure 7 a second example of blade 208 according to the invention will now be described. Similar elements between this dawn 208 and that of Figures 4 to 6 are identified by the same numerical references increased by 100.

Dawn 208 of the figure 7 differs from that of Figures 4 to 6 as regards the corrugated upper portion 222 of the intrados face 216. This upper portion 222 starts far enough from the leading edge of the blade.

This takes into account that only a small portion of the flow passes through gap I in zone J near the leading edge of the blade. Indeed, with reference to the figure 7 it is roughly estimated that 20% of the flow passes through gap I at zone J and thus the remaining 80% of flow passes through gap I at zone K. Therefore, the presence of corrugations according to the invention (ie the succession of alternately concave curves 229 and convex curves 231 along the contour line 230) is particularly useful in zone K. Approximately, Zone J covers a quarter of the dovetail face, starting from the leading edge, while Zone K covers the remaining three quarters.

With reference to the figure 8 , we will now describe a third example of blade 308 according to the invention. The analogous elements between this dawn 308 and that of Figures 4 to 6 are identified by the same numerical references increased by 200.

The example of figure 8 differs from the example of Figures 4 to 6 in that the blade 308 does not have an open cavity at its upper end and, consequently, has no underside or extrados rim.

With reference to the figure 9 , we will describe a fourth example of blade 408 according to the invention. The analogous elements between this dawn 408 and that of Figures 4 to 6 are identified by the same numerical references increased by 300.

Dawn 408 of the figure 9 differs from the example of Figures 4 to 6 in that its intrados flange 436 is set back from the rest of the intrados face. The upper part 422 of the intrados face 416 corresponds to the intrados face of the intrados flange 436.

Thus, while in the first three examples, the upper portion 122, 222, 322 of the intrados face 116, 216, 316 protruded from the rest of the intrados face of the blade, in this fourth for example, the upper portion 422 of the intrados face 416 is set back relative to the remainder of the underside face of the blade.

The upper portion 422 forms with the portion 424 of the end face of the blade, an average edge angle B strictly less than 90 °.

Furthermore, it will be noted that in this fourth example, the intrados flange 436 throughout its width, is corrugated and inclined towards the intrados (thus, even the extrados wall 423 of the flange 436 is corrugated). The intrados flange 436 may be corrugated along its entire length, that is from the leading edge to the trailing edge of the blade, or only over part of its length.

Like the example of the figure 5 , the dawn example of the figure 9 comprises an internal cooling passage 440 and cooling channels 442 communicating with this passage. In on the other hand, the cooling channels 440 do not open on the part 424 of the end face of the blade, but at the base of the intrados flange 436, at the hollow corrugation zones of this rim, c that is, at the concave curves 429 of the contour line 430. Indeed, it is easier to realize the cooling channels 440 there. In addition, the cooling air supplied by the channels 440 rises along the upper portion 422 of the intrados wall (and thus allows the wall to cool) before reaching the gap I.

With reference to the figure 11 a fifth example of blade 508 according to the invention will be described. The analogous elements between this dawn 508 and that of Figures 4 to 6 are identified by the same numerical references increased by 400.

Dawn 508 of the figure 11 differs from the dawn of Figures 9 and 10 in that the extrados rim 538 of this blade is corrugated and inclined towards the lower surface, in the manner of the lower flange 536. Thus, another projecting edge 550 is defined between the end face 554 and the face These portions form between them an angle of average edge G strictly less than 90 ° so as to promote the separation of the flow F of fluid passing through the turbomachine at the edge 550. The intrados face 556 of the extrados rim 538 is corrugated and follows, in any sectional plane perpendicular to the main axis A of the blade, a contour line formed by a succession of alternately concave and convex curves, so that this contour line has an alternation of weakly and strongly inclined segments with respect to the F1 components of the flux F in this section plane.

In the above examples, a blade belonging to a turbojet turbine rotor has been described. Nevertheless, it is clear that the invention can be applied to other types of turbomachines, the yield losses related to the passage of the flow F in the gap I found in other types of turbomachines.

Claims (9)

1. A turbomachine moving blade without a top platform, the blade comprising a fastener root (110) surmounted by an airfoil (112), the airfoil presenting an end face (114) and pressure-side and suction-side faces (116 and 118), the fastener root and said end face being situated respectively at bottom and top ends of the blade that are spaced apart along the main axis (A) of the blade, the airfoil presenting a projecting edge (120) at the top edge of its pressure side, the projecting edge being defined between a portion (124) of the end face and a top portion (122) of the pressure-side face, these portions forming between each other a mean edge angle (B) that is strictly less than 90° so as to encourage the stream (F) of fluid passing through the turbomachine to separate at said edge, the blade being characterized in that the top portion (122) of the pressure-side face is corrugated and, in any section plane perpendicular to the main axis of the blade, follows an outline (130) formed by an alternating succession of concave curves (129) and convex curves (131).
2. A turbomachine blade according to claim 1, in which said top portion (122) of the pressure-side face projects relative to the remainder of the pressure-side face of the blade.
3. A turbomachine blade according to claim 1 or claim 2, having at its top end an open cavity (132) defined by an end wall (134), a pressure-side rim (136), and a suction-side rim (138), and in which said projecting edge (120) is formed on the pressure-side rim between the end face and the corrugated pressure-side face of the pressure-side rim.
4. A turbomachine blade according to any one of claims 1 to 3, including an internal cooling passage (142) and at least one cooling channel (140) communicating with the internal cooling passage, the channel opening out in said portion (124) of the end face in register with the bulging zones in the corrugation of the top portion (122) of the pressure-side face.
5. A turbomachine blade according to claim 3, in which the pressure-side rim (436) is corrugated and inclined towards the pressure side.
6. A turbomachine blade according to claim 5, including an internal cooling passage (442) and at least one cooling channel (440) communicating with the internal cooling passage, said channel opening out at the base of the pressure-side rim (436), in register with the set back zones of the corrugation of said rim.
7. A turbomachine blade according to claim 3, in which another projecting edge (550) is defined between the end face and the pressure-side face of the suction-side rim (538), these portions forming between them a mean edge angle (G) that is strictly less than 90° so as to encourage the stream (F) of fluid passing through the turbomachine to separate at said other edge, and in which the pressure-side face of the suction-side rim (538) is corrugated and, in any section plane perpendicular to the main axis of the blade, follows an outline formed by an alternating succession of concave curves and convex curves.
8. A turbine including a blade according to any preceding claim.
9. A turbomachine including a turbine according to claim 8.

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