FR3079869A1 - HIGH PRESSURE TURBINE BLADE COMPRISING A DEAD CAVITY HAVING A SECTION REDUCTION - Google Patents

Abstract

The invention relates to a turbomachine turbine blade comprising a foot carrying a blade, this blade comprising: - a trombone-type circuit (26) comprising three branches (29, 31) and two connections (33) connecting these branches, the one of the branches (28) being extended by a feeding portion extending in the root of the blade to collect air, one of the connections (33) being extended in the root of the blade by a cavity dead (36); another circuit (27) comprising another branch (38) running along a branch (29) of the trombone-type circuit (26), this other branch (38) being extended by another power supply portion (41) to collect cooling air. According to the invention, the dead cavity (36) of the trombone type circuit (26) comprises a reduction of localized section to be passed by the supply portion (41) of the other circuit (27).

Description

High pressure turbine blade comprising a dead cavity having a reduction in cross-section

DESCRIPTION

TECHNICAL AREA

The invention relates to a turbine blade intended for example to equip an aircraft engine of the turbofan or turboprop type, or else an industrial gas turbine.

PRIOR STATE OF THE ART

In such an engine 1 visible in FIG. 1, air is admitted into an inlet sleeve 2 to pass through a blower 3 comprising a series of rotary blades before splitting into a central primary flow and a secondary flow surrounding the primary flow .

The primary flow is then compressed in compression stages 4 and 6 before arriving in a combustion chamber 7, after which it is expanded through a set of turbines 8 before being discharged to the rear. The secondary flow is propelled directly towards the rear by the fan in a vein delimited by the casing 9.

The expansion which makes it possible to drive the compressor and the blower takes place at high temperature because it occurs immediately after combustion. The blades of the first stages of the turbine which immediately follows the combustion chamber, namely the stages closest to the combustion chamber 7 commonly known as high pressure stages are thus subjected to the most severe conditions.

Such a blade, identified by 11 in FIG. 2, is a hollow monobloc piece originating from foundry, comprising a foot P by which it is fixed to a turbine disk, a blade 12 carried by this foot P, with between foot P and the blade 12 an intermediate region called platform and identified by 13, the foot ending in a lower face 14.

It comprises a leading edge BA oriented radially in a direction of span EV relative to its axis of rotation AX and situated upstream AM of the blade relative to the direction of flow flow in the turbojet engine. This blade also includes a trailing edge BF approximately parallel to the leading edge and spaced from the latter along the axis AX to be located at the level of the downstream region AV. It also comprises a vertex S substantially parallel to the platform 13 and spaced from the latter in the direction of the span EV.

This blade 11 is provided with circuits by which cooling air circulates, represented and schematically in FIG. 3, which here comprises a paper clip type circuit 16 including three branches 17, 18, 19 joined by two connections 21, 22, as well as a feed portion 23 and a dead cavity 24.

The supply portion 23 extends the branch 17 in the foot P by opening into the face 14, to collect cooling air. The dead cavity 24 extends the connection 22 in the foot P, without opening into the face 14 where it is closed.

Concretely, the molding core delimiting the paper clip circuit has two ends which protrude from the supply portion 23 and from the dead cavity 24 which it delimits, and by which it is anchored to a body of the mold. After molding, one of the openings left by the core in the base is closed, for example by soldering, and constitutes the dead cavity 24.

In practice, the paper clip circuit extends in a central portion of the blade along the axis AX, and the blade comprises other circuits for cooling in particular its leading edge and its downstream portion and its edge. leak.

The object of the invention is to provide a solution for adding to such a blade another circuit comprising a branch which runs laterally along one of the branches of the paper clip circuit.

STATEMENT OF THE INVENTION

The subject of the invention is a turbomachine turbine blade comprising a foot carrying a blade, this blade comprising:

- a paperclip type cooling circuit comprising at least two branches spaced from one another in a longitudinal direction with a connection connecting these branches and extending into the foot of the blade by a dead cavity;

- Another cooling circuit comprising another branch laterally skirting a branch of the paper clip type circuit, this other branch being extended by a supply portion contiguous to the dead cavity, this supply portion extending in the foot of the 'blade to collect air and having an oblique part by which it is connected to the other branch;

and in which the dead cavity has a recess which is bordered by the oblique part of the other circuit to allow nesting of the oblique part with the dead cavity without placing the dead cavity in communication with this oblique part.

With this arrangement, the blade has a dead cavity to facilitate its manufacture by authorizing firm anchoring of the core delimiting the paperclip-type circuit, without penalizing the connection to a supply portion of a branch of another circuit running alongside laterally a branch of the paper clip circuit.

The invention also relates to a blade thus defined, in which the paperclip-type circuit comprises three branches spaced apart from each other along the longitudinal direction.

The invention also relates to a blade thus defined, in which the other circuit is a circuit for cooling a leading edge of the blade, this other circuit having its supply portion upstream of the dead cavity.

The invention also relates to a blade thus defined, in which the branch of the trombone circuit followed by the other branch extends from the lower side of the blade, the other branch extending from the upper side of the blade.

The invention also relates to a blade thus defined, in which the connection extended by the dead cavity has in a plane normal to the span direction of the blade a section having the shape of the letter L which partially surrounds the other branch .

The invention also relates to a dawn thus defined, in which one of the branches of the trombone type circuit extends from the lower surface to the upper surface of the dawn.

The invention also relates to a tubine comprising a vane thus defined.

The invention also relates to a turbomachine comprising a blade thus defined.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 already described is a schematic side sectional view of a turbofan engine according to the prior art;

Figure 2 already described is an overview of a high pressure turbine blade according to the prior art;

Figure 3 already described is a schematic view of a paper clip type cooling circuit of a cooling vane according to the prior art;

Figure 4 is a perspective view of a portion of a paper clip type circuit associated with another circuit according to the invention;

Figure 5 is a schematic side view of a paper clip type circuit according to the invention;

Figure 6 is a schematic sectional view of a typ etrombone circuit associated with another circuit according to the invention;

Figure 7 is a partial perspective view of the paperclip-type circuit associated with the other circuit in the region of the dead cavity showing the interference between the dead cavity and the supply portion of the other circuit;

Figure 8 is a partial perspective view of the paperclip-type circuit associated with the other circuit in the region of the dead cavity and showing the recess of the dead cavity to avoid interference with the power portion of the other circuit ;

Figure 9 is a perspective view showing the nesting of the oblique part with the dead cavity according to the invention.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

The arrangement of circuits according to the invention comprises a paper clip type circuit 26 associated with another circuit marked by 27 which are shown in FIGS. 4 to 6.

The paper clip circuit 26 comprises a first, a second and a third branch marked respectively by 28, 29 and 31, extending substantially parallel to the span direction EV of the blade, that is to say substantially perpendicular to a longitudinal axis AX of rotation of this blade.

These three branches are spaced from each other in the longitudinal direction, and they are connected to each other by two connections 32 and 33. This longitudinal direction corresponds to the general orientation of the axis AX, and it also corresponds to the direction of the chord of dawn which is a straight line extending from the leading edge to the trailing edge inscribed in a plane normal to the major direction.

This paper clip circuit includes a supply portion 34, extending its first branch 28 by extending into the base of the blade to collect cooling air.

The first branch 28 is connected to the second branch 29 by the connection 32 which extends substantially longitudinally at the top of this blade. The second branch is in turn connected to the third branch by the connection 33, which also extends longitudinally but being located near the foot of the blade, that is to say in the region of its platform.

The first branch 28 and the second branch 29 both extend along the upper surface wall, while the third branch 31 extends throughout the thickness of the blade, that is to say ie from the upper surface to the lower surface. This paper clip circuit 26 has a so-called snail arrangement, that is to say that, as visible in particular in FIG. 5, the third branch 31 is located between the first and the second branch along the longitudinal direction while being the last branch traversed by the cooling air coming from the supply portion 34.

The connection 33 is extended by a dead cavity 36 extending in the foot of the blade, this dead cavity having a shape similar to that of the supply portion 34 which is contiguous to it in the longitudinal direction, with the difference that it is closed at its end instead of being open there.

The dead cavity 36 results from the molding operation: it corresponds to a portion of the core delimiting the paper clip circuit 26, which serves to maintain this core so that it does not move during casting. Concretely, the core has two ends which protrude beyond the supply portion 34 and the dead cavity 36 which it delimits, and by which it is anchored to the body of the blade mold. Given the large dimensions of a paper clip circuit and the complexity of its shape, such a double anchoring is necessary to ensure adequate maintenance of such a core. After the molding operation, one of the openings left by the core in the base of the blade is closed, for example by brazing, and constitutes the dead cavity 36. The other opening is left open to constitute the portion d supply 34 for supplying air to this paper clip circuit 26.

The paper clip circuit 26 extends in the central part of the blade along the longitudinal direction to typically cool its central part and its top, while the other circuit, namely the upstream circuit 27 extends in the upstream part of dawn to cool its leading edge.

This upstream circuit 27 comprises a branch 38 associated with an upstream ramp 39 supplied by this branch 38 to cool the leading edge of the blade, as well as another supply portion 41 extending the branch 38 in the foot of the dawn to collect cooling air.

The branch 38 of this upstream circuit 27 is located on the lower side of the blade and it laterally runs along the second branch 29 of the paper clip circuit 26 which is located on the upper side of this blade. In other words, the branches 29 and 38 are located at the same level along the longitudinal direction, and they extend parallel to a radial direction relative to the axis ΑΧ.

The snail arrangement of the circuit 26 associated with the upstream circuit 27 makes it possible in fact to have both a downward flow circulating in the branch 29 and an upward flow circulating in the branch 38, which are both located in the region of the edge d attack to cool it.

Thus, and as illustrated in FIG. 6, the connection 33 of the paper clip circuit 26 has a section having the shape of the letter L in a plane normal to the span direction. One of the bars of this L, parallel to the longitudinal direction corresponds to the second branch 29 and the other bar, perpendicular to the longitudinal direction corresponds to the third branch 31. Consequently, and as appears from FIG. 6, the branch 38 is located substantially upstream along the longitudinal direction relative to the branch 31 which it runs along in addition to running along the branch 29.

Given this general arrangement of the paper clip circuit 26 and the upstream circuit 27, the supply portion 41 of the upstream circuit interferes with the dead cavity 36 which is contiguous to it in the region of the foot of the blade.

Concretely, the dead cavity 36 extends parallel to the span direction EV by comprising a cylindrical base 42 transforming into an L-shaped section corresponding to the connection 33 which it extends.

The supply portion 41 also has a cylindrical base 43, contiguous to the base 42 along the longitudinal direction, which is extended by a bent oblique portion 44, of circular section, and by which this base 43 communicates with the branch 38 located opposite the base 42. The bent portion 44 has an oblique orientation, that is to say neither parallel to the longitudinal direction nor parallel to the span direction.

The interference resulting from the oblique orientation of the bent part 44 with respect to the radial orientation of the dead cavity 36 which is contiguous to it would result in a communication of the upstream circuit 27 with the dead cavity 36.

According to the invention, this placing in communication is avoided by virtue of a recess 46 of the dead cavity 36 located in the vicinity of the oblique part 44, which allows this oblique part 44 to go along the dead cavity 36 while being nested therein. everything but separated from it by a curved wall.

This recess 46 which is formed locally on the upstream side of the supply portion at the height of the oblique part 44 corresponds to a portion of the internal wall delimiting the dead cavity 36 which is locally convex when viewed from the interior of this cavity 36 .

This recess 46 has a curve which corresponds to that of the oblique part 44, so that this oblique part 44 is separated from the dead cavity 36 by a curved wall of substantially constant thickness. In the example of the figures, this recess thus has the shape of a cylinder portion to correspond to the shape of the oblique part 44 which is cylindrical.

The continuity of the recess 46 with the rest of the surface delimiting the dead cavity 36 is ensured by curved portions, symbolized by the fictitious edges 47 in FIG. 8, to avoid the formation of sharp edges detrimental to the casting operation of dawn.

The solution found makes it possible to respect the mechanical constraints, as well as the manufacturing constraints without impacting the geometries of the neighboring cavities. This reinforcement having the sole purpose of maintaining the cavity during manufacture, an element must be added to block the outlet at the foot.

Claims (8)

1. Turbomachine turbine blade comprising a foot carrying a blade, this blade comprising: - a paper clip type cooling circuit (26) comprising at least two branches (29, 31) spaced from one another in a longitudinal direction (AX) with a connection (33) connecting these branches and extending into the foot of dawn by a dead cavity (36); - Another cooling circuit (27) comprising another branch (38) laterally skirting a branch (29) of the paper clip type circuit (26), this other branch (38) being extended by a contiguous supply portion (41) to the dead cavity (36), this supply portion (41) extending in the foot of the blade to collect air and comprising an oblique part (44) by which it is connected to the other branch (38); and in which the dead cavity (36) has a recess (46) which is bordered by the oblique part (44) of the other circuit (27) to allow the oblique part (44) to nest with the dead cavity (36 ) without placing the dead cavity (36) in communication with this oblique part (44). 2. Dawn according to claim 1, in which the paper clip type circuit (26) comprises three branches (28, 29, 31) spaced from one another along the longitudinal direction (AX). 3. Dawn according to one of claims 1 to 2, in which the other circuit (27) is a circuit for cooling a leading edge of the blade, this other circuit (27) having its portion of supply (41) upstream of the dead cavity (36). 4. Dawn according to claim 2 or 3, in which the branch (29) of the trombone circuit (26) along laterally by the other branch (38) extends on the lower side of the blade, the other branch (38 ) extending from the upper side of the dawn. S63450 EBL-P 5. Dawn according to one of the preceding claims, in which the connection (33) extended by the dead cavity (36) has in a plane normal to the span direction (EV) of the blade a section having the form of the letter L that surrounds 5 partially the other branch (38). 6. Dawn according to claim 5, in which one of the branches of the trombone-type circuit (26) extends from the lower surface to the upper surface of the dawn. 10 7. Turbine comprising a blade according to one of the preceding claims. 8. A turbomachine comprising a turbine according to claim 7.