Blower rotor comprising blades with upstream center of gravity

Abstract

The invention relates to a shield intended to be attached to and fixed to an upstream end of a blade (6) of a fan rotor of a turbomachine comprising a disc having axial recesses for housing blades (6) with upstream center of gravity, each blade (6) comprising in the direction of flow of an airflow, an upstream end (A) and a downstream end (10a, 60a), a blade (63) intended to work aerodynamically in the airflow, a foot (61) and a strut (62) extending between the blade (63) and the foot (61), the foot (61) being housed in a recess (41); said rotor comprising inter-blade platforms held by means of an annular upstream ferrule integral with the disc;said shield being characterized in that it comprises a tab projecting from an upstream part of the shield and intended to extend upstream and is intended to be in radial contact with the upstream ferrule so that in operation said tab absorbs centrifugal forces from the blade upstream. Figure of the abstract: Fig.5;

Description

Title of the invention: Blower rotor comprising upstream center of gravity blades

[0001] GENERAL TECHNICAL DOMAIN

[0002] The invention relates to the field of double-flow turbomachinery and relates particularly to a shield of a fan rotor blade of such a turbomachine, a blade comprising such a shield and a fan rotor comprising such a blade. STATE OF THE ART

[0003] A double-flow turbomachine classically comprises a fan rotor driving a fan located at the inlet of the turbomachine.

[0004] In a known manner, a blower rotor comprises a disc carrying circumferentially spaced blades on its outer periphery, each blade having a foot engaged in an axial recess located on the outer periphery of the disc. The blades are retained radially on the disc by the shape cooperation of their feet with the recesses of the disc.

[0005] The recesses are oriented substantially axially and have a dovetail cross-section. Their shape is complementary to that of the blade roots to ensure their retention, particularly when the blades are subjected to significant stresses. The blades are mounted individually by being inserted axially into the recesses. The blades are radially wedged by means of an axial wedge positioned between the bottom of the recess and the blade root. The blades are axially held downstream by a stop, which is generally formed by a downstream ferrule integral with the disc, and upstream by means of a locking mechanism fixed to the disc. Upstream and downstream are defined here and in what follows with respect to the direction of gas flow in the turbomachine.

[0006] Conventionally, a blade comprises, in addition to a root, a strut and a blade with an aerodynamic profile, the strut being at the interface between the root and the blade. The blade tip is opposite the root of the blade, having a free end called the blade tip. Furthermore, the blade comprises a leading edge and a trailing edge. The leading edge faces the air and constitutes the leading edge, while the trailing edge constitutes the trailing edge. In order to protect the blade from bird strikes or erosion, a shield is attached to the leading edge of the blade. The shield is attached to the blade.

[0007] In addition, and still classically, the blades have a center of gravity positioned at the barycenter of the blade.

[0008] To increase the efficiency of turbomachinery, it can be advantageous to have a leading edge inclined upstream, specifically at mid-height of the blade between its root and tip, and at its tip near the blade tip. The height is measured by considering a level along the radial length of the blade, for example, at the leading edge. One objective of extending the leading edge upstream is to increase the flow rate captured by the fan. Indeed, the air stream has a conical profile from upstream to downstream of the fan; therefore, the further upstream one is from the fan, the larger the incoming air cross-section, thus increasing the flow rate captured by the fan.

[0009] However, this is not without its problems, since this upstream-shifted center of gravity will generate greater upstream centrifugal forces during operation. This then results in higher stresses at the stilt / root transition of the fan rotor blade. PRESENTATION OF THE INVENTION

[0010] An objective of the invention is to propose a blade which can resist in particular mechanical stresses due to the rotation (centrifugal force) of the blower but whose distribution is impacted by the aerodynamic shape of the blade (center of gravity advanced upstream; stronger mechanical stresses upstream, etc.), as well as intensified centrifugal stresses upstream and consequently stronger mechanical stresses upstream.

[0011] To this end, the invention proposes a shield intended to be attached to and fixed to an upstream end of a blade of a fan rotor of a turbomachine comprising a disc having axial recesses intended to house blades with upstream center of gravity, each blade comprising in the direction of flow of an airflow, an upstream end and a downstream end, a blade intended to work aerodynamically in the airflow, a foot and a strut extending between the blade and the foot, the foot being housed in a recess; said rotor comprising inter-blade platforms held by means of an annular upstream ferrule integral with the disc; said shield being characterized in that it has a tab projecting from an upstream part of the shield and intended to extend upstream and is intended to be in radial contact with the upstream ferrule so that in operation said tab takes centrifugal forces from the upstream blade.

[0012] The invention is advantageously complemented by the following features, taken alone or in any technically possible combination thereof:

[0013] - the leg extends upstream so as to extend from a part of the shield positioned opposite the lower part of Péchasse above the foot;

[0014] - the shield further includes a chamfer to facilitate the insertion of the shield below the ferrule;

[0015] - the shield is obtained by means of an additive manufacturing process by fusion laser, the shield and the leg being a single piece;

[0016] - the tab is machined and attached to the upstream part of the shield;

[0017] The invention also relates to a fan rotor blade comprising a shield according to the invention, said shield being attached and fixed to an upstream end of the blade body, this body being made of composite material comprising a fibrous reinforcement obtained by three-dimensional weaving in which a resin is impregnated.

[0018] The invention also relates to a blower rotor comprising a blade according to the invention.

[0019] The invention also relates to a turbomachine comprising a blower rotor according to the invention.

[0020] The invention also relates to an aircraft comprising a turbomachine according to the invention.

[0021] The advantage of providing the shield with a tab upstream of the shield is that it does not modify the structure of the body of the vane. PRESENTATION OF THE FIGURES

[0022] Other features, objectives and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which:

[0023] [Fig.1] Fig.1 illustrates a turbomachine according to the invention;

[0024] [Fig.2] [Fig.2] illustrates a known type of fan rotor blade of a turbomachine;

[0025] [Fig. 3] [Fig. 3] illustrates a fan rotor blade of a turbomachine according to an embodiment with center of gravity offset upstream to which the invention applies;

[0026] [Fig.4] [Fig.4] illustrates a detail of one embodiment of a blade according to the invention as mounted in a rotor according to the invention;

[0027] [Fig.5] [Fig.5] illustrates a blade of a blower rotor according to the invention.

[0028] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION

[0029] Fig. 1 illustrates a double-flow turbomachine 1 with an upstream blower 2 comprising a blower disc 4 carried by a blower rotor 3 on which are arranged blades 6 held by their base 61 in recesses 41 formed on the outer periphery of the disc 4. The blower rotor is to rotate about an axis X of rotation of the turbomachine.

[0030] It is specified here that the axial direction is understood to be a direction of the X-axis, a radial direction is a direction perpendicular to and passing through this X-axis. Furthermore, the circumferential direction corresponds to a direction perpendicular to the X-axis and not passing through it. In addition, unless otherwise specified, internal and external are used respectively with reference to a radial direction, such that the internal part or face of an element is closer to the X-axis than the external part or face of the same element.

[0031] Fig. 2 illustrates a blade of known type having a center of gravity G positioned at the barycenter of the blade and Fig. 3 illustrates a blade having a center of gravity G shifted upstream relative to the blade of Fig. 2.

[0032] A blade comprises a body 60 made of composite material including a fibrous reinforcement obtained by three-dimensional weaving by forming a preform in which a resin is embedded. This composite material body includes a foot 61, a strut 62, and a blade 63 with an aerodynamic profile. The blade body 60 includes an upstream end 60a and a downstream end 60b.

[0033] The fibrous reinforcement can be formed from a one-piece fibrous matrix obtained by three-dimensional weaving and may include, in particular, carbon, glass, aramid, and / or ceramic fibers. The resin impregnating the preform is typically a polymer, for example, epoxy, bismaleimide, or polyimide. The blade body 60, with its preformed fibrous reinforcement embedded in the resin, is then formed by molding using a vacuum resin injection process of the RTM (Resin Transfer Molding) or VARTM (Vacuum Resin Transfer Molding) type, during which the preform is impregnated with the resin.

[0034] The blade has a leading edge which corresponds to the front part of the aerodynamic profile and which faces the airflow and which divides the airflow on either side of the blade up to a trailing edge which corresponds to the area from which the flow escapes from the blade.

[0035] In relation to [Fig. 4], each blade 66 is mounted in a recess 41 by means of the blade's foot 61. Thus, only the Péchasse 63 and the blade protrude from the disk 4. Between each blade are inter-blade platforms 7 66 which, together with an upstream ferrule 8 fixed to the disk 4, allow for the reconstitution of a gas flow circulation channel. The ferrule 8 allows the inter-blade platforms to be held in place by any suitable means. The platforms 7 can be made of either composite material or metal. A shim 9 can also be mounted between the foot 61 and the bottom of the recess in the disk 4. Furthermore, the blades 6 are locked in the recesses by means of a locking mechanism 13 located between the upstream ferrule and the disk 4.

[0036] Advantageously, referring back to [Fig. 3], in order to protect the blade 6, a shield 10 is attached to the upstream end of the blade 6 and thus forms the leading edge of the blade. The shield is specifically attached to the blade 63 of the blade 6 and covers the upstream end 60a of the blade 6. Such a shield 10 protects the blade 6 from bird strikes and also helps mitigate erosion-related problems.

[0037] Advantageously, the shield 10 is metallic, preferably made of titanium. Other types of metals may be used. It will be understood that the type of material chosen for the shield must meet mechanical and aerodynamic requirements. The shield 10 includes an upstream portion 10a of the shield 10 which, in particular, defines the leading edge of the blade formed by the body to which the shield is attached.

[0038] The attachment of the shield 10 to the body 60 of the blade 6 is implemented by gluing or by brazing on the body 60 of the blade 6.

[0039] Again in relation to [Fig. 4], to compensate for the upstream centrifugal forces on the blade 6 due to its center of gravity being offset upstream, the blade 6 has a protruding lug 11 extending upstream from an upstream end A of the blade 6 and is in radial contact with the annular ferrule 8 so that, during operation, the lug 11 absorbs the upstream centrifugal forces F from the blade. Notably, the center of gravity is offset upstream, particularly considering that for at least 5 percent of the blade height near the blade tip, the leading edge is axially upstream of an axially upstream end of the blade root. In particular, this upstream offset over approximately these 5% of the tip height is inclined upstream. Moreover, in the embodiment as shown in [Fig.3], substantially the entire leading edge of the blade is axially upstream of an axially upstream end of the blade root.In relation to [Fig. 3] and [Fig. 2], specifically, one-third of the blade on the tip side is axially upstream of an axially upstream end of the blade root. Conversely, considering embodiments substantially conforming to [Fig. 2], approximately one-third or one-quarter of the leading edge located on the tip side of the blade is axially set back from this axially upstream end of the blade root. In both cases, in [Fig. 2] and [Fig. 3], a central bulge of the blade, extending over approximately one-quarter of the blade's height, is significantly offset upstream. For the construction of [Fig. 3], over approximately 10 to 15 percent of the blade height near the blade tip, the leading edge is curved upstream, specifically with an upstream offset inclined upstream at its final tip end, for example, for approximately 5 percent of the final height of the blade's leading edge. Conversely, for . the realization of [Fig.2], the curvature on this section of height leading edge is globally curved downstream with its final end substantially radial.

[0040] Indeed, under centrifugal force, the blade 6 deforms due to centrifugal force and aerodynamic pressures. This deformation results in a radial displacement of the blade, which increases the force transmitted through the contact between the upstream ferrule and the shank, thus relieving the Péchasse compared to a blade without a shank.

[0041] In this way, during operation, the blade 6 is maintained in its cavity in the position with its center of gravity G directed upstream without affecting the performance of the turbomachine.

[0042] In relation to [Fig.5], the lug 11 protrudes from the shield 10, more precisely the lug 11 protrudes from an upstream end A of the blade 6 which is here the upstream part 10a of the shield 10 and is in radial contact with the annular ferrule 8 (not visible on [Fig.4]) so that in operation the lug 11 takes centrifugal forces F from the blade upstream.

[0043] The lug 11 is therefore attached to the shield 10 and is preferably a single piece with it. The shield 10 is advantageously manufactured using an additive manufacturing process by laser melting. Machining the lug onto the shield can also be considered. "Single piece" primarily means monolithic, made from a single unit. Alternatively, a lug could be welded onto a shield that already has a lower section on each side to cover each side of the upstream side of Péchasse.

[0044] According to this second embodiment, in order to facilitate the insertion of the shield under the ferrule, the lug 11 includes a chamfer 12 in radial contact with the ferrule 8 above.

[0045] In addition, the lug 11 has on the one hand a circumferential thickness identical to that of the shield 10 and on the other hand radially a height adapted to be mounted with the upstream ferrule 8. Furthermore, the position of the lug 11 on the shield will be determined by the position of the ferrule and more particularly of the inner face of the ferrule.

Claims

Demands

1. A fan rotor blade with an upstream center of gravity (G) comprising, in the direction of airflow, an upstream end (A) and a downstream end (10a, 60a), the upstream center of gravity blade having a leading edge axially upstream of an axially upstream end of the blade root for at least five percent of the blade height near the blade tip, the blade comprising a blade (63) intended to work aerodynamically in the airflow, a root (61) and a stilt (62) extending between the blade (63) and the root (61), the root (61) being intended to be housed in a cavity (41) of a fan rotor disk (4); said blade comprising a shield attached and fixed to an upstream end (60a) of said blade, said disc (4) comprising axial alveoli (41) intended to house blades (6) and inter-blade platforms (7) held by means of an annular upstream ferrule (8) integral with the disc (4);said shield comprising a tab (11) projecting from an upstream part of the shield and intended to extend upstream and is intended to be in radial contact with an upstream ferrule (8) of a rotor so that in operation said tab absorbs centrifugal forces from the upstream blade.;

2. Dawn according to claim 1, wherein the leg (11) extends upstream so as to extend from a part of the shield arranged opposite the lower part of the stilt above the foot.

3. Blade according to any one of claims 1 to 2, further comprising a chamfer to facilitate insertion of the shield below the ferrule (8).

4. According to one of the preceding claims, the shield (10) is obtained by means of an additive manufacturing process by laser melting, the shield and the leg being one piece.

5. Blade according to any one of claims 1 to 3, the tab (11) being machined and attached to the upstream part of the shield.

6. Blade according to any one of the preceding claims, wherein the body (60) is made of composite material comprising a fibrous reinforcement obtained by three-dimensional weaving in which a resin is impregnated.

7. A turbomachine fan rotor comprising a disk having axial cavities and comprising at least one blade according to any one of the preceding claims, said rotor comprising

8.

9. inter-blade platforms and an upstream ferrule, the inter-blade platforms being held in place by means of the annular upstream ferrule attached to the disk. Turbomachine comprising a blower rotor according to the preceding claim. Aircraft comprising a turbomachine according to claim 8.

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