Turbine engine blade assembly

Abstract

The invention relates to a blade assembly (30) of a turbine engine (10), intended to be mounted about a longitudinal axis (X) and comprising: first and second circumferentially adjacent blades (31, 31') extending radially relative to the longitudinal axis (X) and each having an aerofoil profile delimited axially upstream by a leading edge (51, 51') and downstream by a trailing edge (52, 52'), the leading edge (51, 51') and the trailing edge (52, 52') being separated by a chord length (Cx), each blade (31, 31') further comprising a pressure-side wall (54, 54') and a suction-side wall (53, 53') which is opposite the pressure-side wall (54, 54'), the pressure-side wall (54, 54') and the suction-side wall (53, 53') each connecting the leading edge (51, 51') to the trailing edge (52, 52'); a platform (32) comprising a flow stream surface (321), the platform (32) being intended to delimit a primary flow stream (21A) of a flow moving in a main flow direction (SI) from the leading edge (51, 51') towards the trailing edge (52, 52') of each blade (31, 31'), the platform having a suction opening (35, 35') and a delivery opening (36, 36') which is arranged downstream of the suction opening (35, 35').

Description

[0001] DESCRIPTION

[0002] TITLE: TURBOMACHINE BLADE

[0003] Field of invention

[0004] The present invention relates to the field of turbomachines such as turboprops or turbojets.

[0005] More particularly, the invention relates to the field of turbines for aircraft turbomachines, and more specifically still to a blade for a distributor or for a moving wheel of such a turbine.

[0006] State of the prior art

[0007] A conventional aircraft turbomachine turbine comprises one or more stages each consisting of a distributor and a moving wheel. The distributor comprises fixed blades connected by their radially outer end to a casing and which are distributed circumferentially around a longitudinal central axis of the turbine so as to form a stator ring. The moving wheel comprises a disk and blades connected to the disk by their radially inner end while being circumferentially distributed around the disk. The distributor of a stage is configured so that a flow of fluid entering this stage, typically comprising gases from a combustion chamber, is accelerated and deflected by the stator blades towards the blades of the moving wheel of this stage so as to drive the latter in rotation around the longitudinal central axis.

[0008] In general, each nozzle and wheel blade of the turbine comprises a blade and two platforms which radially delimit between them a circumferential portion of an annular primary duct in which the blade extends. The fluid passing through the turbine flows mainly in this primary duct.

[0009] During the operation of a conventional turbine, the interaction of the fluid with the distributors and the moving wheels produces vortices at the level of the blade platforms, forming so-called "secondary" flows.

[0010] To illustrate this phenomenon, Figure 1 shows a portion of two blades IA and IB of a turbine nozzle 1, these blades IA and IB being circumferentially adjacent to each other. Figure 1 shows more particularly a radially internal portion of a blade 2 and a platform 3 of each of the blades IA and IB. The blade 2 of each blade IA and IB comprises a leading edge 4, a trailing edge 5, a lower surface 6 and an upper surface 7. The platform 3 of each blade IA and IB delimits radially inwards a circumferential portion of an annular primary duct in which a fluid flows in a main flow direction SI going from the leading edge 4 to the trailing edge 5 of the blades 2.

[0011] Given the typical viscosity of the fluid flowing in the primary duct of a turbine, its flow along the surface of the platforms 3 has a velocity gradient GV1 such that, in the vicinity of this surface, the velocity of a layer of fluid is lower the closer this layer is to this surface. The fluid flowing in the primary duct is also subjected to a pressure gradient GP1 oriented in this example from the intrados 6 of the blade 2 of the blading 1B towards the extrados 7 of the blade 2 of the blading 1A. The pressure gradient GP1 is generally sufficient to deflect the layers of fluid flowing near the surface of the platforms 3.

[0012] This results in the appearance of different types of vortices. A first type of vortices T1, called "horseshoe", takes the form of two counter-rotating branches distributed on either side of the blades 2. A second type of vortices T2, called "passage vortices", develop between two circumferentially adjacent blades 2. A third type of vortices T3, called "corner vortices", run along the connection lines between the blade 2 and the platform 3 of each blade.

[0013] Such secondary flows T1, T2 and T3, which typically occur at the root and tip of the blades 2, are not oriented in the direction SI of the main flow of the fluid passing through the primary duct and consequently lead to a reduction in the efficiency and an increase in the kerosene consumption of the turbomachine. Similar secondary flows also occur in the moving turbine wheels.

[0014] There is therefore a need to provide blading that can reduce secondary flows upstream of the blading so as to reduce unwanted effects with a detrimental impact on the efficiency of the turbomachine.

[0015] Statement of the invention

[0016] The invention aims to remedy at least in part the drawbacks mentioned above relating to the techniques of the prior art.

[0017] To this end, the invention relates to a turbomachine blade intended to be mounted around a longitudinal axis X and comprising: a first and a second circumferentially adjacent blades which extend radially with respect to the longitudinal axis X and each have an aerodynamic profile delimited axially upstream by a leading edge and downstream by a trailing edge, said leading edge and said trailing edge being separated by a chord distance, each blade further comprising a pressure side wall and an extrados wall opposite said pressure side wall, said pressure side wall and said extrados wall each connecting said leading edge to said trailing edge;a platform comprising a vein surface from which each blade extends, said platform being intended to delimit a primary flow vein of a flow flowing in a main direction from said leading edge to said trailing edge of each blade, said platform having a suction opening and an ejection opening provided downstream of said suction opening.;

[0018] According to the invention, the suction opening opens between the leading edges of the two circumferentially adjacent blades and in that said ejection opening extends over said vein surface in a main direction a substantially orthogonal to said longitudinal axis, and opens onto a part of a substantially rectangular zone, said substantially rectangular zone extending over: a length L1 measured in said main direction a from said trailing edge of the first blade and corresponding to a predetermined inter-blade distance, the inter-blade distance being measured circumferentially between the trailing edge of the first blade and the trailing edge of the second blade, and over a width L2 orthogonal to said main direction a corresponding to a distance less than or equal to a quarter of said chord distance upstream and / or downstream of said trailing edge.

[0019] Thus, the invention proposes a new and inventive approach making it possible to resolve at least in part certain of the drawbacks of the prior art.

[0020] To be as efficient as possible, the shape and position of the ejection opening must meet three criteria: be positioned in a low pressure zone in order to promote suction at the sampling mouth located close to the intrados wall, generate the least pressure losses to most efficiently suck the flow close to the leading edge, and promote the ejection of the flow into the vein in a direction that is as close as possible to that of the main flow SI and this by disturbing it as little as possible. Thus, by implementing an ejection opening that extends in a zone as defined by the invention, this makes it possible to reinject a large part of the flows, without generating any disturbance at the reinjection zone, downstream of the blading radially close to the trailing edge so as to have a passive system based on the upstream and downstream pressure difference.

[0021] Furthermore, such a shape of the ejection opening allows it to be well positioned in a low pressure zone to suck in as much flow as possible, and its adapted shape allows the air to be disturbed as little as possible at the ejection, which reduces pressure losses during flow mixing. This also reduces losses at the downstream blading by reducing the angle and Mach distortion caused by secondary flows close to the blading wall and by significantly reducing the intensity of the vortices at the blading outlet.

[0022] According to a particular aspect of at least one embodiment of the invention, the ejection opening opens downstream of the trailing edges of each of the two circumferentially adjacent blades. According to a particular aspect of at least one embodiment of the invention, said ejection opening has a quadrilateral shape, an oblong shape, a circular shape, an ovoid shape, or a “drop” shape.

[0023] According to a particular aspect of at least one embodiment of the invention, said ejection opening has a rectangular shape, a parallelogram shape, a diamond shape, or a trapezoidal shape.

[0024] According to a particular aspect of at least one embodiment of the invention, said blade comprises an internal channel formed between said suction opening and said ejection opening.

[0025] According to a particular aspect of at least one embodiment of the invention, said internal channel has a sloping ejection portion arranged in the vicinity of said ejection opening, the inclination of said slope of said ejection portion relative to said vein surface being progressive and decreasing towards the ejection opening so that a flow ejected from the internal channel is substantially parallel to the flow flowing in the main flow direction going from said leading edge towards said trailing edge of each blade.

[0026] This prevents separations during ejection which would cause pressure losses and a drop in efficiency in the primary flow stream.

[0027] According to a particular aspect of at least one embodiment of the invention, said platform is an internal platform, said vein surface of said internal platform being adapted to delimit radially inwards said primary flow vein.

[0028] According to a particular aspect of at least one embodiment of the invention, said internal channel has a continuous internal tubular wall.

[0029] In addition, the inner tubular wall is smooth.

[0030] In other words, said internal channel has an internal tubular wall which does not have any roughness or asperity, that is to say which does not have any discontinuity or abrupt break in slope.

[0031] Such a shape thus makes it possible to limit the formation of additional vortices, and to limit pressure losses.

[0032] According to a particular aspect of at least one embodiment of the invention, said suction opening is located in the vicinity of said leading edge. According to a particular aspect of at least one embodiment of the invention, said suction opening has at least one hole having a shape taken from: an oval shape; a scoop shape; a slot shape, or a shape with a biconvex profile.

[0033] The invention also relates to a turbine for a turbomachine comprising: a distributor comprising at least one blading according to any one of the aforementioned embodiments, and / or a moving wheel comprising at least one blading according to any one of the aforementioned embodiments.

[0034] The invention also relates to a turbomachine comprising a turbine according to the aforementioned embodiment.

[0035] Presentation of figures

[0036] The invention, as well as the various advantages that it presents, will be more easily understood in the light of the following description of an illustrative and non-limiting embodiment thereof, and of the appended drawings among which:

[0037] [Fig. 1] is a partial schematic perspective view of a nozzle of a conventional aircraft turbomachine turbine, illustrating secondary flows which occur during operation of the turbomachine;

[0038] [Fig. 2] is a schematic axial sectional view of a propulsion assembly for an aircraft;

[0039] [Fig. 3] is a partial schematic view in axial section of a low pressure turbine of a turbomachine;

[0040] [Fig. 4] is a schematic side sectional view of a blade according to a first embodiment of the invention;

[0041] [Fig. 5] is a schematic sectional view from above of the blading according to the first embodiment of the invention;

[0042] [Fig. 6] is a partial schematic perspective view of the blading according to the first embodiment of the invention, and

[0043] [Fig. 7] is a partial schematic perspective view of the blading according to a second embodiment of the invention.

[0044] Detailed description of an embodiment of the invention The figures presented comprise a reference frame L, R and C respectively defining longitudinal (or axial), radial and circumferential directions orthogonal to each other.

[0045] Figure 2 shows an aircraft propulsion unit 10 comprising a turbomachine 11 shrouded by a nacelle 12. In this example, the turbomachine 11 is a twin-spool, twin-flow turbojet.

[0046] Subsequently, the terms “upstream” and “downstream” are defined with respect to a direction SI of flow of gases through the propulsion unit 10 when the latter is propelled.

[0047] The turbojet 11 has a longitudinal central axis X around which its various components extend, in this case, from upstream to downstream, a fan 13, a low-pressure compressor 14, a high-pressure compressor 15, a combustion chamber 16, a high-pressure turbine 17 and a low-pressure turbine 18. The compressors 14 and 15, the combustion chamber 16 and the turbines 17 and 18 form a gas generator.

[0048] During operation of the turbojet 11, an air flow enters the propulsion unit 10 through an air inlet upstream of the nacelle 12, passes through the fan 13 and then divides into a central primary flow and a secondary flow. The primary flow flows in a primary gas circulation duct 21A passing through the gas generator. The secondary flow flows in a secondary duct 21B surrounding the gas generator and delimited radially outwards by the nacelle 12.

[0049] In an exemplary embodiment, the low pressure turbine 18 is as described below with reference to FIG. 3 which shows the turbine 18 along a radial plane which includes the longitudinal central axis X.

[0050] The longitudinal central axis X is also the axis of rotation of the rotor of this turbine 18.

[0051] In this example, the turbine 18 comprises four stages each comprising a distributor 25 and a moving wheel 26.

[0052] In a manner known per se, the moving wheels 26 are assembled axially to each other by annular flanges T1 and form the rotor of the turbine 18. The distributors 25 are connected to a casing 28 to form the stator of the turbine 18.

[0053] Each distributor 25 comprises a plurality of blades 30 circumferentially distributed around the axis X. With reference to the distributor 25 of the last stage of the turbine 18 of which a single blade 30 is shown in FIG. 3, the blades 30 each comprise a first blade 31 and a second blade 31', an internal platform 32 and an external platform 33. The blades 30 are each connected to the casing 28 by a fastening element secured to their external platform 33.

[0054] Each moving wheel 26 comprises, for its part, a disc and a plurality of blades circumferentially distributed around the axis X. With reference to the moving wheel 26 of the last stage of the turbine 18, of which only one blade is shown in FIG. 3, the blades each comprise a first blade and a second blade, an internal platform and an external platform. The blades are each connected to the disc by a foot secured to their internal platform.

[0055] For each vane 30 of distributor 25, the platforms 32 and 33 each comprise a first surface from which each of the blades 31, 31' extends and which delimits a circumferential portion of the primary duct 21A in which the primary flow circulates. Thus, the first surface of the internal platform 32 of each vane 30 delimits the primary duct 21A radially inwards while the first surface of the external platform 33 of each vane 30 delimits the primary duct 21A radially outwards.

[0056] Similarly, for each moving wheel blade, the platforms each comprise a first surface from which each of the blades extends and which delimits a circumferential portion of the primary duct 21A. Thus, the first surface of the internal platform of each blade delimits the primary duct 21A radially inwardly while the first surface of the external platform of each blade delimits the primary duct 21A radially outwardly.

[0057] In the turbine 18 of Figure 3, the primary duct 21A is therefore generally annular.

[0058] A first embodiment of the invention is now presented in relation to Figures 4 to 6.

[0059] It should be noted that this first embodiment applies to a blade for a distributor or a blade for a moving turbine wheel of a turbomachine.

[0060] As illustrated in these different figures, each blade 30 comprises: a first blade 31 and a second blade 31' circumferentially adjacent extending radially with respect to the longitudinal axis X; a platform 32 comprising a vein surface 321 from which each blade 31, 31' extends, the platform being intended to delimit a primary flow vein 21A of a flow flowing in a direction SI going from the leading edge 51 towards the trailing edge 52 of each of the blades, this platform 32 having a suction opening 35 and an ejection opening 36 arranged downstream of the suction opening 35.

[0061] Here, the platform 32 is an internal platform, the vein surface 321 of the internal platform 32 radially inwardly delimiting the primary flow vein 21A.

[0062] In this embodiment, the blading comprises an internal channel 34 formed between this suction opening 35 and this ejection opening 36. This internal channel 34 has a continuous internal tubular wall so as not to generate additional swirling flows and so as to limit pressure losses and therefore load losses. In other words, said internal channel has a smooth internal tubular wall.

[0063] In other words, said internal channel has an internal tubular wall which does not have any roughness or asperity which could disturb the fluid flow.

[0064] The first blade 31 has an aerodynamic profile delimited axially upstream by a leading edge 51 and downstream by a trailing edge 52, the leading edge 51 and the trailing edge 52 being separated by a chord distance Cx. The first blade 31 further comprises a pressure side wall 54 and an extrados wall 53 opposite the pressure side wall 54, such that the pressure side wall 54 and the extrados wall 53 each connect the leading edge 51 to the trailing edge 52.

[0065] For its part, the second blade 31' has an aerodynamic profile delimited axially upstream by a leading edge 51' and downstream by a trailing edge 52', the leading edge 51' and the trailing edge 52' being separated by a chord distance Cx'. The second blade 31' further comprises a pressure side wall 54' and an extrados wall 53' opposite the pressure side wall 54', such that the pressure side wall 54' and the extrados wall 53' each connect the leading edge 51' to the trailing edge 52'.

[0066] According to the invention, the suction opening opens between the leading edges 51, 51' of the two circumferentially adjacent blades 31, 31'.

[0067] Furthermore, according to the invention, the ejection opening 36 extends over the vein surface 321 in a main direction a substantially orthogonal to the longitudinal axis X, and opens onto a part of a substantially rectangular zone 9.

[0068] According to the invention, this substantially rectangular zone 9 extends over: a length L1 measured along the main direction a from the trailing edge 52 and corresponding to a predetermined inter-blade distance, the inter-blade distance being circumferentially measured between the trailing edge 52 of the first blade 31 and the trailing edge 52' of the second blade 31', and over a width L2 orthogonal to the main direction a corresponding to a distance which is less than or equal to a quarter of the chord distance Cx, and this upstream and / or downstream of the trailing edge 52.

[0069] Thus, this zone carried by the platform linked to the blades extends in two dimensions, that is to say it extends in a first dimension in a direction between the two blades of the blading, and extends in a second dimension orthogonal to the first dimension between a point located at a distance which is less than or equal to a quarter of the chord distance Cx, upstream and a point located at a distance which is less than or equal to a quarter of the chord distance Cx downstream of the trailing edge.

[0070] In other words, the entire ejection opening opens at the vein surface so as to be positioned inside this substantially rectangular zone 9.

[0071] As a result, the ejection opening has dimensions less than or equal to those of zone 9. This ejection opening 36 here has a quadrilateral shape, and more particularly a parallelogram shape.

[0072] According to other embodiments, it could in particular be provided that the ejection opening has a rectangular shape, a diamond shape, a square shape, or a trapezoidal shape.

[0073] It would also be possible to provide an embodiment as illustrated in FIG. 7, in which the ejection opening 36' has a substantially oval shape.

[0074] An ejection opening could also be provided having an oblong shape, a circular shape, an ovoid shape, or a "drop" shape.

[0075] In this embodiment, the ejection opening 36 opens downstream of the trailing edges 52, 52' of each of the two circumferentially adjacent blades 31, 31'.

[0076] As can be seen in particular in Figures 4 and 6, the internal channel 34 has a sloping ejection portion 360 arranged in the vicinity of the ejection opening 36. This inclination of the slope of the ejection portion 360 relative to the flow path surface 321 is progressive and decreases towards the ejection opening 36 so that a flow ejected from the internal channel 34 is substantially parallel to the flow flowing in a main flow direction SI going from the leading edge 51, 51' towards the trailing edge 52, 52' of each blade 31, 31'.

[0077] In other words, moving away from the ejection opening 36 from this ejection opening 36, therefore in the opposite direction to the flow which is intended to circulate within the internal channel 34, the slope of the ejection portion 360 increases going towards the upstream of the internal channel 34 until the end of this ejection portion 360.

[0078] As illustrated in particular in Figure 5, in the first embodiment, the suction opening 35 is located in the vicinity of the leading edge 51, 51' of each of the blades.

[0079] The suction opening 35 illustrated in FIG. 4 has an ovoid shape oriented in a main direction forming an angle substantially equal to 30 degrees with a direction passing through the leading edge 51 and the trailing edge 52, and also an angle substantially equal to 30 degrees with a direction configured to pass through the leading edge 51 of the first of the two blades 30, and a leading edge of the second of the two blades 30'.

[0080] In this embodiment, the internal channel also has a sloping suction portion 350 arranged in the vicinity of the suction opening 35. This inclination of the slope of the suction portion 350 relative to the vein surface 321 is progressive and decreases towards the suction opening 35. In other words, moving away from the suction opening from this suction opening, the slope of the suction portion increases towards the downstream of the internal channel 34 until the end of this suction portion. The suction opening 35' of the second embodiment, illustrated in FIG. 7, has a "drop" shape.

[0081] In other embodiments not shown, the suction opening could have an oblong shape, a circular shape, or an ovoid shape.

Claims

CLAIMS

1. A turbomachine (10) vane (30) intended to be mounted around a longitudinal axis (X) and comprising: a first and a second circumferentially adjacent blade (31, 31') which extend radially with respect to the longitudinal axis (X) and each have an aerodynamic profile delimited axially upstream by a leading edge (51, 51') and downstream by a trailing edge (52, 52'), said leading edge (51, 51') and said trailing edge (52, 52') being separated by a chord distance (Cx), each blade (31, 31') further comprising a lower surface wall (54, 54') and an upper surface wall (53, 53') opposite said lower surface wall (54, 54'), said lower surface wall (54, 54') and said upper surface wall (53, 53') each connecting said leading edge (51, 51') to said trailing edge (52, 52'); a platform (32) comprising a vein surface (321),said platform (32) being intended to delimit a primary flow vein (21A) of a flow flowing in a main flow direction (SI) going from said leading edge (51, 51') towards said trailing edge (52, 52') of each blade (31, 31'); said platform (32) having a suction opening (35, 35') and an ejection opening (36, 36') arranged downstream of said suction opening (35, 35'), characterized in that the suction opening (35, 35') opens between the leading edges (51) of the two circumferentially adjacent blades (31, 31') and in that said ejection opening (36, 36') extends over said vein surface (321) in a main direction (a) substantially orthogonal to said longitudinal axis (X), and opens onto a part of a substantially rectangular zone (9),the substantially rectangular zone (9) extending over: a length (L1) measured along said main direction (a) from said trailing edge (52) of the first blade (31) and corresponding to a predetermined inter-blade distance, the inter-blade distance being measured circumferentially between the trailing edge (52) of the first blade (31) and the trailing edge (52') of the second blade (31'), and over a width (L2) orthogonal to said main direction (a) corresponding to a distance less than or equal to a quarter of said chord distance (Cx) upstream and / or downstream of said trailing edge (52).,

2. Blading according to the preceding claim, characterized in that the ejection opening (36') opens downstream of the trailing edges (52, 52') of each of the two circumferentially adjacent blades (31, 31').

3. Blading according to one of the preceding claims, characterized in that said ejection opening (36) has a quadrilateral shape, an oblong shape, a circular shape, an ovoid shape, or a “drop” shape.

4. Blading according to one of the preceding claims, characterized in that it comprises an internal channel (34) formed between said suction opening (35, 35') and said ejection opening (36, 36').

5. Blading according to the preceding claim, characterized in that said internal channel (34) has a sloping ejection portion (360) arranged in the vicinity of said ejection opening (36, 36'), the inclination of said slope of said ejection portion (360) relative to said vein surface (321) being progressive and decreasing towards the ejection opening (36, 36') so that a flow ejected from the internal channel (34) is substantially parallel to the flow flowing in the main flow direction (SI) from said leading edge (51, 51') to said trailing edge (52, 52') of each blade (31, 31').

6. Blading according to one of claims 4 or 5, characterized in that said internal channel (34) has a continuous internal tubular wall.

7. Blading according to one of the preceding claims, characterized in that said platform (32, 33) is an internal platform (32), said vein surface (321) of said internal platform (32) being adapted to delimit radially inwards said primary flow vein (21A).

8. Blading according to one of the preceding claims, characterized in that said suction opening (35, 35') is located in the vicinity of said leading edge (51, 51').

9. Blading according to one of the preceding claims, characterized in that said suction opening (35, 35') has a shape taken from: an oval shape; a scoop shape; a slot shape, or a shape with a biconvex profile.

10. Turbine for a turbomachine comprising: a distributor comprising at least one blading according to any one of claims 1 to 9, and / or a moving wheel comprising at least one blading according to any one of claims 1 to 9.

11. A turbomachine comprising a turbine according to claim 10.

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