BE1026276B1 - INTER-BLADES OF AXIAL TURBOMACHINE COMPRESSOR - Google Patents

Abstract

The subject of the invention is an annular row of blades (26) of an axial turbomachine, for example of a low-pressure compressor of an aircraft turbojet engine. The row includes: an annular surface (50); an annular vane array extending radially from the annular surface and comprising two successive vanes with curved airfoils (64); a passage (44) between the two successive blades (26) where the annular surface (50) has a main bump (68) projecting radially into said axial passage. The main hump (68) comprises a middle line (70) matching the aerodynamic profiles of the two successive blades.

Description

Description

INTER-BLADES OF AXIAL TURBOMACHINE COMPRESSOR

Technical area

The invention relates to non-axisymmetric humped surfaces between blades of an axial turbomachine. The invention also provides a blade with a hump platform. The invention also relates to a compressor with a humpback ferrule (s). The invention also relates to an axial turbomachine, in particular an aircraft turbojet or an aircraft turboprop.

Prior art

Document FR3011888 A1 discloses a turbomachine part comprising at least a first blade, a second blade, and a platform from which the blades extend. The platform has a nonaxisymmetric surface limited by a first and a second extremal plane, and defined by at least two construction curves of class Cl each representing the value of a radius of said surface as a function of a position between the lower surface of the first blade and the upper surface of the second blade in a plane substantially parallel to the extremal planes, of which: a first increasing curve in the vicinity of the second blade; a second curve disposed between the first curve and a trailing edge of the first and second blades, and decreasing in the vicinity of the second blade. However, the dips at the corner of the dawn degrade the flow.

Summary of the invention

Technical problem

The object of the invention is to solve at least one of the problems posed by the prior art. More specifically, the invention aims to reduce dips at the corner of the dawn. The invention also aims to provide a simple, resistant, light, economical, reliable solution, easy to produce, convenient to maintain, and easy to inspect.

Technical solution

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The subject of the invention is an annular row of axial turbomachine blades, in particular of an axial turbomachine compressor, the row having: an annular surface; an annular row of vanes extending radially from the annular surface, said vanes comprising two successive vanes with curved aerodynamic profiles; an axial passage between the two successive blades where the annular surface has a main boss projecting radially in said axial passage; remarkable in that the main bump comprises a curved average line following the curved aerodynamic profiles of the two successive blades.

According to advantageous modes of the invention, the annular row of vanes can comprise one or more of the following characteristics, taken in isolation or according to all the possible technical combinations:

- The mean line of the main hump is identical to one of the mean lines of the aerodynamic profiles, or comprises a section identical to a section of curved mean line of aerodynamic profiles; said sections possibly extending over the axial majority of the main hump.

- Depending on the circumference, the thickness of the main bump is greater than the thickness of the aerodynamic profiles, preferably the thickness of the main bump is three to six times the thickness of the aerodynamic profiles, values included, possibly the thickness of the main bump is equal to four times the thickness of the aerodynamic profiles.

- The passage has a circumferential gap between the two successive blades, the thickness of the main bump extending over 5% to 25%, values included, of the circumferential gap.

- The main bump has an upstream climb extending axially over 10% to 30%, values included, of the main bump.

- The main bump has an upstream end downstream of the leading edges of the two successive blades.

- The main hump has a downstream end downstream of the trailing edges of the two successive blades.

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- Depending on the circumference, the main bump is equidistant from each of the two successive blades.

- The main bump extends axially over 50% to 120% of the two successive blades, preferably over 50% to 100% of the two successive blades.

- The maximum radial height of the main hump is 1% to

1.5% of the radial height H of the two successive blades.

- The annular surface has auxiliary bumps in contact with the leading edges of the successive blades.

- The annular surface has main recesses upstream of the leading edges of the successive blades.

- Each main hollow is upstream and / or in contact with an auxiliary hump.

- The annular surface has axisymmetric separations isolating the main bump from the two successive blades, each axisymmetric separation extends over the majority of the two successive blades.

- Each of the two successive blades comprises a radius of connection with the annular surface, the auxiliary bumps forming enlargements with respect to said connection radii.

- Each auxiliary bump is axially and circumferentially at a distance from the main bump.

- The constant height extends axially over 40% to 80% of the length of the main hump.

- The width of the main hump is constant, especially over the majority of its length.

- The main hump has a downstream descent from the annular surface, the downstream descent extending axially over 10% to 30% of the main hump.

- The main bump occupies 5% to 15% of the annular surface.

- The thicknesses are maximum thicknesses.

- The aerodynamic profiles are radially at the level of the annular surface.

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- The main bump axially overlaps the majority of the two successive blades.

- The maximum radial height of the hump is measured in relation to the annular surface.

- The main bump has a constant height over most of its axial length.

- The annular surface comprises an axisymmetric junction in contact with the two successive blades, and / or the main bump, and / or axisymmetric separations.

The invention also relates to an axial turbomachine blade, in particular of a turbojet compressor, the blade having come in one piece and comprising a blade with an arcuate aerodynamic profile, and a fixing platform with a fixing portion and a base surface. whence extends said blade radially, the base surface forming in particular an annular surface portion; the base surface having at least one main bump extending radially with respect to the base surface, remarkable in that the main bump comprises a curved mean line following the curved aerodynamic profile of said blade, said blade forming in particular one of the two successive blades according to the invention.

The invention also relates to an axial turbomachine compressor, in particular a low-pressure axial turbomachine compressor, the compressor comprising an annular row of blades and / or a blade, remarkable in that the annular row of blades conforms to the invention; and / or the blade conforms to the invention; preferably the main bump is a first bump, the annular surface having an annular row of identical bumps to which the first bump belongs.

According to an advantageous embodiment of the invention, the compressor comprises a primary vein and an internal ferrule with an external surface forming the annular surface and delimiting the primary vein.

According to an advantageous embodiment of the invention, the compressor comprises an external casing, in particular made of an organic matrix composite material, the fixing platform being fixed to said external casing.

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The invention also relates to a turbomachine, in particular an aircraft turbojet engine, comprising an annular row of blades and a compressor, characterized in that the annular row of blades conforms to the invention, and / or the compressor is in accordance with the invention.

According to an advantageous embodiment of the invention, the turbomachine comprises a fan axially at a distance from the compressor and / or from the annular row of blades, radially at the level of the main boss, the fan optionally comprises straight aerodynamic profiles.

In general, the advantageous modes of each object of the invention can also be combined with the other objects of the invention. Each object of the invention can be combined with the other objects, and the objects of the invention can also be combined with the embodiments of the description, which in addition can be combined with one another, according to all possible technical combinations, unless the opposite is not explicitly mentioned.

Benefits

The invention limits detachments. The invention notably makes it possible to conserve part of the flow against the upper surfaces. It also makes it possible to channel the possible vortices formed by the recesses, in particular thanks to the shape of the merlon of the main hump. Thus, the boundary layers disturb the rest of the flow less.

Brief description of the drawings

FIG. 1 represents an axial turbomachine according to the invention.

FIG. 2 is a diagram of a turbomachine compressor according to the invention.

FIG. 3 illustrates a plan view of a passage between two consecutive blades according to the invention.

Figure 4 is a sectional view of the passage along the axis IV-IV shown in Figure 3.

Figure 5 is a sectional view of the passage along the V-V axis shown in Figure 3.

FIG. 6 represents a blade of a turbomachine according to the invention.

Description of the embodiments

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In the following description, the terms "internal" and "external" refer to a positioning relative to the axis of rotation of an axial turbomachine. The axial direction corresponds to the direction along the axis of rotation of the turbomachine. The radial direction is perpendicular to the axis of rotation. Upstream and downstream are in reference to the main flow direction of the flow in the turbomachine.

Figure 1 shows a simplified axial turbomachine. In this case, it is a double-flow turbojet engine. The turbojet engine 2 comprises a first level of compression, called a low-pressure compressor 4, a second level of compression, called a high-pressure compressor 6, a combustion chamber 8 and one or more levels of turbines 10. In operation, the mechanical power from the turbine 10 transmitted via the central shaft to the rotor 12 sets in motion the two compressors 4 and 6. The latter comprise several rows of rotor blades associated with rows of stator blades. The rotation of the rotor around its axis of rotation 14 thus makes it possible to generate an air flow and to gradually compress the latter until the inlet of the combustion chamber 8.

An inlet fan commonly designated as a fan or blower 16 is coupled to the rotor 12 and generates an air flow which is divided into a primary flow 18 passing through the various aforementioned levels of the turbomachine, and into a secondary flow 20 passing through an annular duct. (partially shown) along the machine to then join the primary flow at the turbine outlet. The fan can be of the non-faired type, for example with double counter-rotating rotor, possibly downstream.

Reduction means, such as a planetary reducer, can reduce the speed of rotation of the blower and / or the low-pressure compressor relative to the associated turbine. The secondary flow 20 can be accelerated so as to generate a thrust reaction necessary for the flight of an aircraft.

FIG. 2 is a sectional view of a compressor of an axial turbomachine such as that of FIG. 1. The compressor can be a low pressure compressor 4. A portion of the fan 16 can be seen there at a distance from the compressor, and the separation nozzle 22 for the primary flow 18 and the secondary flow 20. The rotor 12 comprises several rows of rotor blades 24,

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BE2018 / 5314 7 in this case three. It can be a bladed monobloc drum or include a disc with rotor blades connected by platforms with dovetail fixing.

The low-pressure compressor 4 comprises several rectifiers, in this case four, each containing a row of stator vanes 26. Some stator vanes may have an adjustable orientation, also called variable pitch vanes. The rectifiers are associated with the fan 16 or with a row of rotor blades to straighten the air flow, so as to convert the speed of the flow into pressure, in particular into static pressure.

The stator vanes 26 extend essentially radially from an external casing 28. This external casing 28 can have an annular wall 30 fixed to an intermediate casing 32 as at the separation spout 22. Fixing platforms 34 make it possible to fix the stator vanes 26 to the casing 28. The platforms 34 can have a fixing portion such as a fixing pin 36 passing through the wall 30. Layers of abradable material 38 can surround the rotor vanes 24 in order to form seals. The layers of abradable 38 can be in contact with the platforms 34.

Internal ferrules 40 can be fixed in overhang at the internal ends of the stator vanes 26. The internal ferrules 40 contribute to delimit the primary vein 42; in combination with platforms 34 and layers of abradable 38.

Figure 3 outlines a plan view of an annular row of blade portion, where two successive blades are shown. It can be blades 26, in particular a compressor, for example low pressure, as detailed in relation to one of FIGS. 1 to 2. The axis of rotation 14 provides an orientation.

The two successive blades 26 border between them a passage 44 which passes axially through the annular row of blades 26. The passage 44 is in particular delimited by a lower surface 46, a upper surface 48, and an annular surface 50. The blades 26 can s extend radially from the annular surface 50. At the inlet 52, the passage 44 can be delimited upstream by the leading edges 54 of the blades 26, while their trailing edges 56 can mark the outlet 58 of the passage 44. According to the circumference 60, passage 44

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BE2018 / 5314 has a circumferential distance 62 which may correspond to its width. The difference 62 can be measured on the leading edges 54 and possibly on the trailing edges 56; in particular at the level of the annular surface 50 radially.

The blades 26 each have a radial stack of aerodynamic profiles 64. These profiles 64 are framed by the lower surface 48 and upper surface 46. Each aerodynamic profile 64 may comprise a set of circles tangent to the lower surface 46 and to the upper surface 48. The meeting of the centers of these circles makes it possible to draw an average line 66 of each profile 64.

The annular surface 50 has a main bump 68, possibly the only bump arranged in the passage 44. This main bump 68 extends along the passage 44. Its general shape is curved. It can be at a distance from each of the blades 26. The main hump 68 has a mean line 70, also curved. This mean line 70 can be equidistant from the blades 26, and can be parallel to the mean lines of the blades 26. The mean line 70 of the main hump 68 can comprise a section identical to part of the mean line 66 of the blades 26.

The main bump 68 can be axially set back from the blades 26. It can be downstream from the inlet 52 of the passage 44. The downstream setback can be equal to 25% of the axial length of the blades 26. The length of the hump can represent from 80% to 100% of the length of the blades 26 and therefore of the passage 44. Optionally, the hump 68 extends downstream of the passage, and therefore crosses the outlet 58. It comprises a zone downstream of the edges of leak 56.

The maximum or average width of the main bump 68 can be greater than the maximum width of the profiles 64 of the blades 26. For example, the maximum or average width of the main bump 68 is equal to four times the maximum width of the profiles 64 of the blades .

The annular surface 50 may include axisymmetric partitions 72 on either side of the main boss 68. These partitions 72 delimit and touch both the blades 26 and the boss 68. Thus, the boss 68 remains away from the vanes 26. In addition, the annular surface 50 may have an axisymmetric junction 74 extending from one of the two vanes 26 to the other. The axisymmetric junction 74 can pass circumferentially through the passage 44.

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It can be in contact with the main bump 68 and the axisymmetric separations 72. Thus, the passage 44 has two paths bypassing the bump 68 while being in contact with axisymmetric surfaces (72; 74).

Optionally, the annular surface 50 has an auxiliary bump 76 against each leading edge 54. Each auxiliary bump 76, also called upstream bump, can be upstream and / or separated from the main bump 68.

Optionally, the annular surface 50 has main recesses

78. Each main recess 78 may be associated with a blade 26, and in particular placed upstream of the corresponding leading edge 54. Each main recess 78 may be outside the passage 44. Each main recess 78 may be in contact with an auxiliary bump 76, and / or separated from the main bump 68.

Although two blades and only one main posse is represented, the present teaching can be applied to the entire row of blades, and to a whole row of identical main bumps alternating with the blades.

FIG. 4 represents a section of the annular row of vanes 26 along the axis IV-IV plotted in FIG. 3. A single blade 26 is representative of its row.

The main bump 68 sinks radially into the passage 44, towards the primary flow 18. Thus, the bump 68 influences the boundary layer of the primary flow 18. The main bump 68 is axially at a distance from the auxiliary bump 76 which possibly follows at the main hollow 78. The axisymmetric junction 74 can separate the main bump 68 from the auxiliary bump 76, in particular in the grip of the passage 44.

The main hump 68 can have a progressive upstream ascent 80 and / or a progressive downstream descent 82. The ascent 80 can be downstream of the leading edge 54. The descent 82 can cross axially the trailing edge 56, or at least the outlet 58 of the passage 44 which it marks. Thus, the apex 84 can be placed between the leading edges 54 and the trailing edges 56.

The main hump 68 can have a constant height H, for example over the majority of its length. The vertex 84 can form the zone of constant height.

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Since the primary vein 42 can be convergent, the annular surface 50 can deviate from the axis 14 downstream. Thus at a point on the axis 14, the radius R against each axisymmetric separation 72 can remain constant around said axis. However, the radius R can vary along the axis of rotation 14.

FIG. 5 represents a section of the annular row of vanes 26 along the axis V-V plotted in FIG. 3. The two successive vanes 26 are seen from the front, along the axis of rotation 14.

The annular surface 50 is shown using a solid line. A dotted line corresponds to a reference area with a constant radius RC. The constant radius RC remains in contact with the axisymmetric separations 72. By subtracting the constant radius RC, a variable radius RV makes it possible to measure the height of the main bump 68, in particular in contact with the vertex 84.

The blades 26 may have connecting radii 86 in connection with the annular surface 50. At this point, the variable radius RV makes it possible to measure the distance from the axis 14.

According to the circumference 60, the main bump 68 has an arcuate profile. Arched connections 88 can delimit it laterally. The arcuate connections 88 can be in contact with the axisymmetric separations 72.

FIG. 6 represents a stator blade 26 with its fixing platform 34 on which a main boss 68 is formed. The meeting of the blade 26, the fixing platform 34 and the fixing axis 36 can form a blade 90 , preferably in one piece. Blade 90 can be produced by additive manufacturing

The main bump 68 can be made in one piece, or be shared on two successive platforms of two successive blades, respectively of successive blades 90. The lateral edges 92 of the platform 34 can cut and / or share the main bumps 68. The radial height and / or the circumferential width of the main boss 68 is greater than that of the connecting spokes 86.

The main bump (s) 68 may not be shown to scale. Generally, the radial height of each main bump 68 is less than 5% of the height of the blade 26. Optionally, the blade 26 comprises

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BE2018 / 5314 a height representing fifty to one hundred times the height of each main bump. The blade 26 can measure 15 cm, and the main bump can measure mm, said measurements being in particular elevations relative to the annular surface 50. The platform 34 thickens on at the level of the bumps 68, and thins in between, in particular against the axisymmetric separations 72. The auxiliary bump 76 has a radial height less than that of each main bump 68. In the axial view, each main bump 68 can be offset and angularly distant from the auxiliary bump 76. The axisymmetric separations 72 of the annular surface 50 can be inserted angularly between them.

Each bump, hollow can be indifferently formed on a platform, or a ferrule; internal or external. Although the present teaching has been detailed in relation to one or more stator vanes 26, it can also be applied to one or more rotor vanes.

Claims (10)

claims 1. Annular row of blades (24; 26) of an axial turbomachine (2), in particular of a compressor (4; 6) of an axial turbomachine (2), the row having: - an annular surface (50); - An annular row of vanes (24; 26) extending radially from the annular surface (50), said vanes (24; 26) comprising two vanes (24; 26) successive with curved aerodynamic profiles (64); - A passage (44) between the two successive blades (24; 26) where the annular surface (50) has a main boss (68) projecting radially in said passage (44); characterized in that the main bump (68) comprises a curved middle line (70) matching the aerodynamic profiles (64) curved of the two successive blades (24; 26). 2. Row according to claim 1, characterized in that the middle line (70) of the main hump (68) is identical to one of the middle lines (66) of the aerodynamic profiles (64), or comprises a section identical to a section mean line (66) aerodynamic profile curve (64); said sections extending over the axial majority of the main hump (68). 3. Row according to one of claims 1 to 2, characterized in that, depending on the circumference, the thickness of the main hump (68) is greater than the thickness of the aerodynamic profiles (64), preferably the thickness of the main bump (68) represents from three times to six times the thickness of the aerodynamic profiles (64), possibly the thickness of the main bump (68) is equal to four times the thickness of the aerodynamic profiles (64). 4. Row according to one of claims 1 to 3, characterized in that the passage (44) has a circumferential distance (62) between the two successive blades (24; 26), the thickness of the main bump (68) ranging from 5% to 25%, values included, of the circumferential difference (62). 2018/5314 BE2018 / 5314 5 19. Turbomachine (2), in particular an aircraft turbojet, comprising an annular row of blades (24; 26) and a compressor (4; 6), characterized in that the annular row of blades (24; 26 ) conforms to one of claims 1 to 14, and / or the compressor conforms to one of claims 16 to 18. 5. Row according to one of claims 1 to 4, characterized in that the main hump (68) comprises an upstream rise (80) extending axially over 10% to 30%, values included, of the main hump (68 ). 6. Row according to one of claims 1 to 5, characterized in that the main hump (68) has an upstream end downstream of the leading edges (54) of the two successive blades (24; 26). 7. Row according to one of claims 1 to 6, characterized in that the main boss (68) has a downstream end downstream of the trailing edges (56) of the two successive blades (24; 26). 8. Row according to one of claims 1 to 7, characterized in that according to the circumference, the main boss (68) is equidistant from each of the two successive blades (24; 26). 9. Row according to one of claims 1 to 8, characterized in that the main hump (68) extends axially over 50% to 120% of the two successive blades (24; 26), preferably over 50% to 100% of the two successive vanes (24; 26). 10. Row according to one of claims 1 to 9, characterized in that the maximum radial height H of the main boss (68) represents from 1% to 1.5% of the radial height of the two blades (24; 26) successive. 11. Row according to one of claims 1 to 10, characterized in that the annular surface (50) has auxiliary bumps (76) in contact with the leading edges of the successive blades (24; 26). 12. Row according to one of claims 1 to 11, characterized in that the annular surface (50) has main recesses (78) upstream of the leading edges of the successive blades (24; 26). 13. Row according to claims 11 and 12, characterized in that each main recess (78) is upstream and / or in contact with an auxiliary hump (76). 2018/5314 BE2018 / 5314 14. Row according to one of claims 1 to 13, characterized in that the annular surface (50) comprises axisymmetric separations (72) isolating the main bump (68) from the two successive blades (24; 26), each axisymmetric separation (72) extends axially over the majority of the two successive vanes (24; 26). 15. Blade (90) of an axial turbomachine (2), in particular of a turbojet compressor, the blade having come in one piece and comprising a blade (24; 26) with an arcuate aerodynamic profile (64), and a fixing platform (34) with a fixing portion and a base surface from which the said blade (24; 26) extends radially, the base surface forming in particular an annular surface portion (50); the base surface having at least one main bump (68) forming a radial allowance on the base surface, characterized in that the main bump (68) comprises a curved mean line (70) matching the aerodynamic profile (64) said blade (24; 26), said blade forming in particular one of the two successive blades according to one of claims 1 to 14. 16. Compressor (4; 6) of axial turbomachine (2), in particular a low-pressure compressor (4) of axial turbomachine (2), the compressor comprising an annular row of blades (24; 26) and / or a blade (90), characterized in that the annular row of blades (24; 26) conforms to one of claims 1 to 14; and / or the blade (90) according to claim 15; preferably the main bump (68) is a first bump, the annular surface (50) having an annular row of identical bumps to which the first bump belongs. 17. Compressor (4; 6) according to claim 16, characterized in that it comprises a primary vein (42) and an internal ferrule (40) with an external surface forming the annular surface (50) and delimiting the primary vein ( 42). 2018/5314 BE2018 / 5314 18. Compressor (4; 6) according to one of claims 16 to17, characterized in that it comprises an external casing (28), in particular of composite material with organic matrix, the fixing platform (34) being fixed to said casing external (28). 20. A turbomachine (2) according to claim 19, characterized in that it comprises a fan (16) axially at a distance from the compressor and / or from the annular row of blades (24; 26), radially at the level of the main bump (68) the blower (16) comprises straight aerodynamic profiles.