Blower rotor comprising blades with upstream center of gravity

Abstract

The invention relates to a fan rotor of a turbomachine comprising: a disk having axial cells; blades with upstream center of gravity, each mounted in a cell, each blade comprising, in the direction of airflow, an upstream end (60a) and a downstream end, 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 cell (41); inter-blade platforms held by means of an annular upstream ferrule integral with the disk; The rotor is characterized in that the blade has a protruding lug (11, 66) extending upstream from an upstream end (A, 10a, 60a) of the blade and is in radial contact with the upstream ferrule such that, during operation, said lug absorbs centrifugal forces from the upstream blade. (See abstract figure: 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 turbomachines and relates particularly to a blower rotor of such a turbomachine and even more particularly to the fixing of the blower blades in their housing on a blower disk. 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] Classically, 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 a leading edge, while the trailing edge constitutes a trailing edge.

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

[0008] In order to increase the efficiency of turbomachinery it may be advantageous to have a leading edge inclined upstream, in particular on the one hand at mid-height of the blade between its root and its tip and on the other hand 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 moving the leading edge upstream is to increase the flow rate captured by the fan. Indeed, the air stream corresponding to the fan has a conical profile from upstream to downstream; 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 blower rotor comprising blades with upstream center of gravity which can withstand in particular intense aerodynamic forces as well as intensified upstream centrifugal forces and consequently stronger upstream mechanical stresses.

[0011] To this end, the invention proposes a blower rotor for a turbomachine comprising:

[0012] . a disc comprising axial alveoli;

[0013] . blades with upstream center of gravity each mounted in a cavity, 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 stilt extending between the blade and the foot, the foot being housed in a cavity;

[0014] . inter-blade platforms held by means of an upstream annular ferrule attached to the disc;

[0015] The rotor is characterized in that the blade has a protruding leg from one upstream end of the blade upstream and is in radial contact with the upstream ferrule so that in operation said leg takes centrifugal forces from the blade upstream.

[0016] The invention is advantageously complemented by the following features, taken alone or in any technically possible combination thereof:

[0017] - the leg extends upstream from the lower part of Péchasse above the foot ;

[0018] - the awl comprises a body which includes the blade, the foot and the stilt, the leg forming projection from the body of the dawn;

[0019] - the body is made of composite material comprising a preform obtained by weaving three-dimensional, the leg being one piece with the body and is obtained during the weaving, the said preform being inserted into an injection mold in order to inject a resin into it so as to obtain the body of the blade;

[0020] - the leg being one piece with the body and is obtained during weaving, said body with its leg being produced by impregnating the preform with a resin in a molding operation;

[0021] - the body is made of composite material comprising a fibrous reinforcement obtained by weaving three-dimensional in which a resin is impregnated by impregnation during a molding including the molding of the leg by the resin to obtain the body of the blade with its impregnated reinforcement;

[0022] - the dawn further comprises a shield attached and fixed to the upstream end of the body, said shield forming an attack edge of the dawn.

[0023] - the dawn further comprises a shield attached and fixed to the upstream end of the body, said shield forming a leading edge of the dawn, the leg projecting upstream from the shield;

[0024] - the leg includes a chamfer at its upstream end to facilitate the ferrule assembly;

[0025] - the leg and the shield also covering the leg include a chamfer at their upstream ends to facilitate the assembly of the ferrule;

[0026] The invention also relates to a turbomachine comprising a blower rotor according to the invention. PRESENTATION OF THE FIGURES

[0027] 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:

[0028] [Fig.1] Fig.1 illustrates a turbomachine according to the invention;

[0029] [Fig.2] [Fig.2] illustrates a known type of fan rotor blade of a turbomachine;

[0030] [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;

[0031] [Fig.4] [Fig.4] illustrates a detail of a first embodiment of a blade according to the invention as mounted in a rotor according to the invention;

[0032] [Fig. 5] [Fig. 5] illustrates the blade of a fan rotor of a turbomachine according to the first embodiment of the invention;

[0033] [Fig. 6] [Fig. 6] illustrates a fan rotor blade of a turbomachine according to a second embodiment of the invention.

[0034] In all figures, similar elements bear identical references. DETAILED DESCRIPTION

[0035] 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.

[0036] It is specified here that the axial direction is understood to be a direction of the X-axis, and the radial direction is a direction perpendicular to and passing through the X-axis. Furthermore, the circumferential direction corresponds to a direction perpendicular to and not passing through the X-axis. 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.

[0037] 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 offset upstream with respect to the blade of Fig. 2.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] In relation to [Fig. 4], each blade 6, 6' is mounted in a recess 41 by means of the blade foot 61 of the blade 6, 6'. Thus, only the Péchasse 63 and the blade protrude from the disk 4. Between each blade are provided inter-blade platforms 7 6, 6' which, with an upstream ferrule 8 fixed to the disc 4, allows for the reconstitution of a gas flow 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 cavity in the disc 4. Furthermore, the blades 6, 6' are locked in the cavities by means of a locking mechanism 13 located between the upstream ferrule and the disc 4.

[0042] Advantageously, referring back to [Fig. 3], in order to protect the blade 6, 6', a shield 10 is attached to the upstream end of the blade 6, 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, 6' from bird strikes and plays a role in mitigating erosion-related problems.

[0043] 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.

[0044] The attachment of the shield 10 to the body 60 of the blade 6, 6' is implemented by gluing or by brazing on the body 60 of the blade 6, 6'.

[0045] Again in relation to [Fig.4], to compensate for the centrifugal forces of the blade 6, 6' upstream due to the center of its center of gravity being offset upstream, the blade 6 has a tab 11, 66 projecting from an upstream end A of the blade 6, 6' upstream and is in radial contact with the annular ferrule 8 so that in operation the tab 11, 66 takes back centrifugal forces F from the blade upstream.

[0046] Indeed, under centrifugal force, the blade 6, 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.

[0047] In this way, during operation, the blade 6, 6' is maintained in its cavity in the position with its center of gravity G directed upstream without affecting the performance of the turbomachine.

[0048] According to a first embodiment illustrated in [Fig. 5], the lug 66 projects from the blade body 60. More precisely, the lug 66 projects from the upstream end 60a of the blade body 62. This is in fact the part of the blade that is covered by the inter-blade platforms 7 downstream and by the ferrule 8 upstream. The lug 66 has a circumferential thickness substantially identical to that of the blade body 6 and radially a height adapted for mounting with the upstream ferrule. The height will depend in particular on the percentage of centrifugal force that one wishes to transmit through the protruding lug / ferrule interface, the geometry of the blade (center of gravity, mass, etc.), the rotational speed, etc.

[0049] In this case, the leg 66 can be obtained during the weaving of the preform, the preform then being inserted into an injection mold in order to inject a resin into it so as to obtain the body 60 of the blade 6. It is possible to consider the finalization of the leg 66 by machining, that is to say that a preform with an upstream excess length is woven and injected and the leg is obtained by machining.

[0050] Alternatively, still assuming that the tab 66 protrudes from the blade body 60, the tab 66 is obtained by injecting resin into the mold to create the blade body, the mold having an impression for the tab. Here, the tab is not obtained by weaving but after the weaving process. As with the rest of the body, the tab can be finished by machining the resin. Alternatively, the tab can be glued to the blade body.

[0051] Thus, as will be understood, the blade body 60 and the lug 66 are monoblocs. By monobloc, we primarily mean monolithic, made from a single piece. We may, where applicable, consider a lug whose resin is attached and bonded to the body resin after an initial molding, for example by overmolding or bonding with an adhesive, although attaching the lug implies less mechanical strength than a monolithic lug.

[0052] According to this first embodiment (see [Fig.5]), the shield 10 is attached to and fixed to the body of the blade and covers the upstream end 60a of the blade 6. In this embodiment as shown, the shield locally overlaps the leg for example without mutual support but does not cover the leg in its overlength projecting from the leading edge of the blade which is defined by the free edge of the upstream end of the shield.

[0053] According to a second embodiment, illustrated in [Fig.6], the leg 11 protrudes from the shield 10, more precisely the leg 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 in [Fig.4]) so that in operation the leg 11 takes centrifugal forces F from the blade upstream.

[0054] Unlike the first embodiment, in the second embodiment, the tab 11 is located on the shield 10 and is preferably integral with it. The shield 10 is advantageously manufactured using an additive manufacturing process by laser melting. Machining the tab on the shield can also be considered.

[0055] According to this second embodiment or also in the first 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.

[0056] In addition, the lug 11 has a circumferential thickness substantially identical to that of the shield 10 and radially a height adapted to be mounted with the upstream ferrule 8. Moreover, 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.

[0057] Furthermore, in an embodiment not shown, by combining the first and second embodiments, the body and the shield each have a leg that are joined together by gluing. The legs can be radially overlapped in contact with each other, and the leg of the shield can also laterally overlap the leg of the body, in addition to the radial overlap.

[0058] Regarding the center of gravity offset upstream: notably, the center of gravity of the blade 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. Corresponding to [Fig. 3] with respect to [Fig. 2], in particular, 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. 3], the center of gravity of the blade is offset upstream of an axially upstream end of the blade root.[2], approximately one-third to 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 its height, is significantly offset upstream. For the realization of [Fig. 3], over approximately 10 to 15 percent of the blade height near the blade tip, the leading edge is curved upstream, particularly 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 over this leading-edge height segment is generally curved downstream, with its final end being substantially radial.

Claims

Demands

1. A turbomachine fan rotor comprising: . a disk (4) having axial recesses (41); . blades (6, 6') with upstream center of gravity (G), each mounted in a cavity (41), each blade (6, 6') comprising, in the direction of airflow, an upstream end (60a, 10a) and a downstream end (60b), the blade with upstream center of gravity 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 strut (62) extending between the blade (63) and the root (61), the root (61) being housed in a cavity (41); . inter-blade platforms (7) held by means of an annular upstream ferrule (8) integral with the disk (4); .the rotor is characterized in that the blade (6, 6') has a protruding lug (11, 66) from an upstream end (A, 10a, 60a) of the blade upstream and is in radial contact with the upstream ferrule (8) so that in operation said lug takes centrifugal forces from the upstream blade.

2. Blower rotor according to claim 1, wherein the leg (11, 66) extends upstream from the lower part of the stilt above the foot.

3. Blower rotor according to claim 2, wherein the blade (6) comprises a body (60) which includes the blade, the foot (61) and the leg (66) projecting from the body (60) of the blade.

4. Blower rotor according to claim 3, wherein the body (60) is made of composite material comprising a preform obtained by three-dimensional weaving, the leg (66) being one piece with the body (60) and is obtained during weaving, said preform being inserted into an injection mold in order to inject a resin into it so as to obtain the body of the blade (6).

5. A blower rotor according to claim 3, wherein the body (60) is made of a composite material comprising a fibrous reinforcement obtained by three-dimensional weaving, in which a resin is impregnated by impregnation during a molding process comprising the molding of the leg (66) by the resin for obtaining the body of the blade (6) with its impregnated reinforcement.

6. Blower rotor according to any one of claims 3 to 5, wherein the blade (6) further comprises a shield (10) attached and fixed to the upstream end (60a) of the body (60), said shield (10) forming a leading edge of the blade.

7. Blower rotor according to any one of claims 3 to 6, wherein the blade (6') further comprises a shield (10) attached and fixed to the upstream end of the body, said shield forming a leading edge of the blade, the tab (11) projecting upstream from the shield.

8. Blower rotor according to any one of claims 1 to 7, wherein the lug (11) includes a chamfer (12) at its upstream end to facilitate the mounting of the ferrule (8).

9. Blower rotor according to claim 7 and claim 8, wherein the lug (11) and the shield also covering the lug comprise a chamfer (12) at their upstream ends to facilitate the mounting of the ferrule (8).

10. Turbomachine comprising a blower rotor according to any one of the preceding claims.

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