FR3108664A1 - Fan rotor with upstream center of gravity vanes - Google Patents

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 comprising axial cells intended to house the blades (6) at the center. of upstream gravity, each blade (6) comprising in the direction of flow of an air flow, an upstream end (A) and a downstream end (10a, 60a), a blade (63) intended to work aerodynamically in the air flow, a foot (61) and a stilt (62) extending between the blade (63) and the foot (61), the foot (61) being housed in a cell (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 lug projecting from an upstream part of the shield and intended to extend upstream and is intended to be in radial contact with the upstream shell so that, in operation said tab takes up centrifugal forces from the blade upstream. Abstract figure: Fig. 5

Description

Fan rotor comprising upstream center of gravity vanes

GENERAL TECHNICAL AREA

The invention relates to the field of dual-flow turbomachines and particularly relates to a shield of a blade of a fan rotor of such a turbomachine, a blade comprising such a shield and a fan rotor comprising such a blade.

STATE OF THE ART

A dual-flow turbomachine conventionally comprises a fan rotor driving in rotation a fan located at the inlet of the turbomachine.

In known manner, a fan rotor comprises a disc bearing on its outer periphery vanes, spaced apart circumferentially each comprising a foot engaged in an axial cell located on the outer periphery of the disc. The blades are retained radially on the disc by form cooperation of their roots with the cells of the disc.

The cells are oriented substantially axially and have a dovetail section. Their shape is complementary to that of the blade roots to allow them to be held in place, particularly when the blades are subjected to significant forces. The blades are mounted individually by being introduced axially into the cells. The blades are wedged radially by means of an axial wedge placed between the bottom of the cell and the root of the blade. The blades are held axially downstream by a stop which generally consists of a downstream shroud secured to the disc and upstream by means of a lock fixed to the disc. Upstream and downstream are defined here and in what follows with respect to the direction of flow of the gas flows in the turbomachine.

Conventionally, a blade comprises, in addition to a root, a stilt and a blade having an aerodynamic profile, the stilt being at the interface between the root and the blade. The blade head is opposite the root of the blade, having a free end called the blade tip. Furthermore, the blade includes an upstream end and a downstream end. The upstream end faces the air and constitutes a leading edge while the downstream end constitutes a trailing edge. In order to protect the blade against bird strikes or erosion, a shield is added to the upstream of the blade and then forms the leading edge of the blade. The shield is notably attached to the blade.

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

In order to increase the efficiency of turbomachines, it may be interesting to have a leading edge leaning upstream. , in particular on the one hand at mid-height of the blade between its root and its head and on the other hand at its head near the tip of the blade. The height is assessed by considering a level on the radial extent of the blade, for example at the leading edge. One purpose of advancing the leading edge upstream is to increase the flow captured by the fan. Indeed, the vein has in correspondence of the fan a conical profile from upstream to downstream, so the more one is upstream of the fan, the more the section of incoming air increases by giving the possibility of increasing the flow picked up by the blower.

However, this is not without problems insofar as this center of gravity shifted upstream will generate, in operation, greater centrifugal forces upstream. This then leads to higher stresses at the stilt/root transition of the fan rotor blade.

PRESENTATION OF THE INVENTION

An object of the invention is to provide a blade which can withstand in particular mechanical forces due to the rotation (centrifugal force) of the fan 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 forces upstream and consequently stronger mechanical stresses upstream.

To this end, the invention proposes a shield intended to be attached and fixed to an upstream end of a blade of a fan rotor of a turbomachine comprising a disk comprising axial cells intended to house blades with an upstream center of gravity. , each vane comprising, in the direction of flow of an air stream, an upstream end and a downstream end, a blade intended to work aerodynamically in the air stream, a root and a stilt extending between the blade and the foot, the foot being lodged in a cell; said rotor comprising inter-blade platforms held by means of an annular upstream shroud secured to the disc; said shield being characterized in that it comprises a lug projecting from an upstream part of the shield and intended to extend upstream and is intended to be in radial contact with the upstream shroud so that in operation said tab picks up centrifugal forces from dawn to upstream.

The invention is advantageously completed by the following characteristics, taken alone or in any of their technically possible combination:

- the leg extends upstream so as to extend from a part of the shield placed in front of the lower part of the stilt above the foot;

- the shield also includes a chamfer making it easier to insert the shield below the ferrule;

- the shield is obtained by means of an additive manufacturing process by laser fusion, the shield and the bracket being one-piece;

- the lug is machined and attached to the upstream part of the shield;

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

The invention also relates to a fan rotor comprising a blade according to the invention.

The invention also relates to a turbomachine comprising a fan rotor according to the invention.

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

The advantage of providing the shield with a tab upstream of the shield means that the structure of the blade body is not modified.

PRESENTATION OF FIGURES

Other characteristics, objects and advantages of the invention will emerge from the description which follows, which is purely illustrative and not limiting, and which must be read in conjunction with the appended drawings in which:

FIG. 1 illustrates a turbomachine according to the invention;

FIG. 2 illustrates a blade of known type of a fan rotor of a turbomachine;

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

FIG. 4 illustrates a detail of an embodiment of a blade according to the invention as mounted in a rotor according to the invention;

FIG. 5 illustrates a blade of a fan rotor according to the invention.

In all the figures, similar elements bear identical references.

DETAILED DESCRIPTION

FIG. 1 illustrates a dual-flow turbomachine 1 with a fan 2 upstream comprising a fan disc 4 carried by a fan rotor 3 on which are arranged blades 6 retained by their root 61 in cells 41 provided on the outer periphery of disc 4. The fan rotor rotates about an axis X of rotation of the turbomachine.

It is specified here that by axial direction is meant a direction of the X axis, a radial direction, a direction perpendicular to this X axis and passing through it. Moreover, the circumferential direction corresponds to a direction perpendicular to the X axis and not passing through it. Also, unless otherwise specified, internal and external are, respectively, used 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.

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 with respect to the blade of FIG. 2 .

A blade comprises a body 60 made of composite material comprising a fibrous reinforcement obtained by three-dimensional weaving by constituting a preform in which a resin is embedded. This composite material body comprises a foot 61, a stilt 62 and a blade 63 with an aerodynamic profile. The body 60 of the blade comprises an upstream end 60a and a downstream end 60b.

The fibrous reinforcement can be formed from a fibrous matrix in one piece obtained by three-dimensional weaving and can notably comprise carbon, glass, aramid and/or ceramic fibers. The resin impregnating the preform is for its part typically made of polymer, for example epoxy, bismaleimide or polyimide. The body 60 of the blade 6 with its fibrous reinforcement in preform embedded in the resin is then formed by molding by means of a resin vacuum injection process of the RTM type (in English, “ Resin Transfer Molding ”) or again VARTM (in English, “ Vacuum Resin Transfer Molding ”), during which the preform is impregnated with the resin.

The blade has a leading edge that matches the front of the airfoil and faces the airflow and divides the airflow across the blade to an edge leakage which corresponds to the zone from which the flow of the blade escapes.

In relation to FIG. 4 , each blade 66 is mounted in a cell 41 via the root 61 of the blade 66. Thus only the stilt 63 and the blade protrude from the disc 4. Between each blade are provided platforms 7 inter-blades 66 which, with an upstream shroud 8 fixed to the disc 4, makes it possible to reconstitute a gas flow circulation vein. The shroud 8 makes it possible to hold the inter-blade platforms in place by means of any suitable means. The platforms 7 can be made either of composite material or of metal. A wedge 9 can also be mounted between the foot 61 and the bottom of the cell of the disc 4. In addition, the blades 6 are locked in the cells by means of a lock 13 placed between the upstream shroud and the disc 4 .

Advantageously, returning to Figure 3, in order to protect the blade 6, a shield 10 is attached to the upstream of the blade 6 and then forms the leading edge of the blade. The shield is in particular attached to the blade 63 of the blade 6 and covers the upstream end 60a of the blade 6. Such a shield 10 makes it possible to protect the blade 6 against bird strikes and plays a role vis-à-vis issues related to erosion.

Advantageously, the shield 10 is metallic, preferably titanium. Other types of metals can be provided. It will be understood that the type of material chosen for the shield must satisfy mechanical and aerodynamic constraints. The shield 10 comprises a part 10a upstream of the shield 10 which determines in particular the leading edge of the blade consisting of the body to which the shield is attached.

The fixing of the shield 10 to the body 60 of the blade 6 is implemented by gluing or by soldering on the body 60 of the blade 6.

Again in relation to FIG. 4, to compensate for the centrifugal forces of the blade 6 upstream due to the center of its center of gravity offset upstream, the blade 6 comprises a lug 11 projecting from a upstream end A of the blade 6 upstream and is in radial contact with the annular shroud 8 so that in operation the lug 11 picks up centrifugal forces F from the blade upstream. Notably, the center of gravity is in particular offset upstream, considering in particular 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 on approximately these 5% of summit height is tilted upstream. In addition, in the embodiment as shown in Figure 3, substantially the entire leading edge of the blade is axially upstream of an axially upstream end of the blade root. In correspondence of Figure 3 with respect to Figure 2, in particular the third of the blade on the head side is axially upstream of an axially upstream end of the blade root. On the contrary, considering embodiments substantially in accordance with FIG. 2, approximately one third or one quarter of the leading edge located on the blade tip side is axially set back from this axially upstream end of the blade root. In both cases in Figure 2 and Figure 3, a central bulge of the blade over substantially a quarter of the height of the blade is particularly offset upstream. For the embodiment of FIG. 3, over approximately 10 to 15 percent of the height of the blade near the tip of the blade, the leading edge is curved upstream, in particular in the upstream offset inclined towards the upstream for its final tip end, for example for approximately 5 percent of the final height of the leading edge of the blade. Conversely, for the embodiment of Figure 2, the curvature on this section of leading edge height is generally curved downstream with its final end substantially radial.

Indeed, in centrifugal mode, the blade 6 is deformed due to the centrifugal force and the aerodynamic pressures. This deformation involves a radial displacement of the blade which leads to an increase in the force which passes through the contact between the upstream shroud and the leg and thus relieves the stilt compared to a blade without a leg.

In this way, in operation, the blade 6 is maintained in its cell in the position with its center of gravity G directed upstream without harming the performance of the turbomachine.

In relation to FIG. 5 , tab 11 projects from shield 10, more precisely tab 11 projects from an upstream end A of blade 6 which is here the upstream part 10a of shield 10 and is in radial contact with the annular shroud 8 (not visible in FIG. 4) so that in operation the lug 11 picks up centrifugal forces F from the blade upstream.

The tab 11 is therefore on the shield 10 and is preferably integral with the latter. The shield 10 is advantageously manufactured by means of an additive manufacturing process by laser fusion. Machining of the bracket on the shield can also be considered. By monobloc, we consider above all monolithic of the same piece. We can, if necessary, consider a leg which would be welded on a shield which would already have a lower section on each of its sides to respectively cover each of the sides of the upstream side of the stilt.

According to this second embodiment, in order to facilitate the insertion of the shield under the ferrule, the leg 11 comprises a chamfer 12 in radial contact with the ferrule 8 above.

In addition, the tab 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 shroud 8. Furthermore, the position of the tab 11 on the shield will be determined by the position of the ferrule and more particularly the internal face of the ferrule.

Claims (9)

Shield intended to be attached and fixed to an upstream end of a blade (6) of a fan rotor of a turbomachine comprising a disc (4) comprising axial cells (41) intended to house blades (6) at upstream center of gravity (G), each vane (6) comprising, in the direction of flow of an air flow, an upstream end (A) and a downstream end (10a, 60a), a blade (63) intended to work aerodynamically in the air flow, a foot (61) and a stilt (62) extending between the blade (63) and the foot (61), the foot (61) being housed in a cell (41) ; said rotor comprising inter-blade platforms (7) held by means of an annular upstream shroud (8) secured to the disc (4); said shield being characterized in that it comprises a lug (11) projecting from an upstream part of the shield and intended to extend upstream and is intended to be in radial contact with the upstream shroud (8) so so that in operation said leg takes up the centrifugal forces of the blade upstream. A shield as claimed in claim 1, wherein the leg (11) extends upstream so as to extend from a portion of the shield disposed opposite the bottom of the stilt above the foot. Shield according to one of claims 1 to 2, further comprising a chamfer making it possible to facilitate the insertion of the shield below the ferrule (8). Shield according to one of the preceding claims, the shield (10) is obtained by means of an additive manufacturing process by laser fusion, the shield and the bracket being in one piece. Shield according to one of claims 1 to 3, the lug (11) being machined and attached to the upstream part of the shield. Blade of a fan rotor comprising a shield according to one of the preceding claims, said shield being attached and fixed to an upstream end (60a) of the body (60) of the blade, this body being made of composite material comprising a reinforcement fiber obtained by three-dimensional weaving in which a resin is impregnated. Fan rotor comprising a blade according to claim 6. Turbomachine comprising a fan rotor according to the preceding claim. Aircraft comprising a turbomachine according to claim 8.