RU2576354C2 - Compressor drum of axial turbine machine with double device for blade locking - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: drum contains wall, on a whole rotating-symmetrical relatively to rotor axis , and having on a whole bent profile. Wall is intended for several blade rows installation on it. First blades row is made by ring flange, made integrally with wall at top of its profile relatively to the axis. Second row of blades is made directly downstream the first and third blade rows directly upstream the first row is made by one or several slots to fix the blades made on the wall. The first blades row and drum create single assembly excluding any oscillations. Blades securing is mixed. Rotor can be installed in casing with ring stators.

EFFECT: reduced oscillations in rotor of axial turbine machine.

15 cl, 3 dwg

Description

BACKGROUND OF THE INVENTION

The present invention relates to a rotor of an axial turbomachine. More specifically, the present invention relates to a rotor drum of an axial turbomachine compressor. The present invention relates to an axial turbomachine equipped with a rotor drum of a low pressure compressor.

State of the art

The turbomachine provides compression, combustion and expansion of gas. Due to this, the turbomachine produces mechanical energy. To this end, the turbomachine comprises a compressor and a turbine equipped with a rotor and a housing.

The inner surface of the casing and the outer surface of the rotor form the contour of the primary flow path. Its annular cross-section is variable. The diameter of the inner and outer contour can increase and decrease along the axis of the engine. In a compressor, especially in a low pressure compressor, the outer casing typically has a reduced diameter in the downstream direction. In the direction from the side upstream to the side downstream, the diameter of the rotor may increase and then decrease. This combination of surfaces provides a wide inlet section and a high compression ratio at the outlet.

To transfer mechanical work to the fluid, both the casing and the compressor rotor contain several annular rows of blades. The rows of rotor blades and the rows of stator vanes alternate in the axial direction.

The housing may contain several annular stators, each of which contains an annular row of blades. The stators form rings that axially abut one another in order to assemble them. In this case, each blade in the row of the rotor is connected to the rotor by means of a shank, which is inserted into the annular groove formed on the rotor.

When assembling a compressor with a rotor in the form of a drum, the first row of blades is mounted on the rotor, and then the stator is assembled so that it is directed axially towards this first row. Only after this, the second row of blades can be installed on the rotor behind the stator relative to the first row. The assembly is continued likewise in the forward direction, collecting a series of rotor and stator vanes one after another. This method of assembly is necessary in view of the fact that the stators are made integrally and their internal diameters do not allow a rotor with blades to be inserted into them.

Patent FR 2845436 B1 discloses an axial turbomachine compressor. The compressor comprises an outer casing formed of several stators assembled in the axial direction. It also contains annular rows of blades, each of which is located between the stators. The rotor blades are attached by means of shanks, which are inserted into the annular grooves made in the rotor. Such an embodiment allows a compressor, the assembly of which is simple, to be performed. However, the rotor is subject to vibration. It creates complex forms of vibrations that are difficult to analyze and quench. Moreover, for its implementation requires complex and expensive machining. In addition, it has a bulky and heavy construction.

SUMMARY OF THE INVENTION

Technical challenge

The aim of the present invention is to solve at least one of the problems inherent in the prior art. More specifically, an object of the present invention is to reduce oscillations in a rotor of an axial turbomachine. Another objective of the present invention is to reduce the mass of the rotor of the axial turbomachine.

Technical solution

The present invention relates to a rotor drum of an axial turbomachine, in particular a low pressure compressor, wherein the drum comprises a wall generally rotationally symmetrical about its axis as a whole with a curved profile, said wall being configured to mount several rows of blades; the first row of blades is formed by an annular shelf made integrally with the wall at the top of its profile relative to the axis; and at least one, preferably each, second row of blades directly downstream of the first and third row of blades and immediately upstream of the first is formed by one or more grooves for fixing the blades made on the wall.

According to an advantageous embodiment of the present invention, the outer surface of the locking groove (s) is at an average distance from the axis, which is less than the average distance of the shelf from the first row to the specified axis.

According to an advantageous embodiment of the present invention, the wall on its outer surface comprises a set of annular ribs adapted to mate with the annular layer of abradable material to provide a seal, wherein the set of annular ribs is made in the axial direction between the first and second row of blades and / or between the first and third row of blades.

According to an advantageous embodiment of the present invention, the minimum interval between the vertices of one set of ribs relative to the axis is greater than the minimum distance from the specified axis to the outer surface of adjacent fixing grooves. This refers to the groove (s) of the second and / or third row of the row (s) of blades.

According to an advantageous embodiment of the present invention, the blades of the first row are welded to the shelf of said row.

According to an advantageous embodiment of the present invention, the shelf of the first row of blades comprises a blade leg to which a blade extension is welded; preferably the height of the blade legs is more than 10% of the radial height of the blade in the first row, more preferably more than 25%.

According to an advantageous embodiment of the present invention, the first row of blades is at least partially cut into the body of the untreated drum.

According to an advantageous embodiment of the present invention, the overall curved wall profile extends for the most part of the drum length and / or has a main concavity directed towards the main axis and extending along most of the drum length, with the radius of said profile relative to the axis having the greatest value on the first row of vanes.

According to an advantageous embodiment of the present invention, the shelf of the first row of blades protrudes relative to the wall immediately above and downstream of said row.

According to an advantageous embodiment of the present invention, the wall comprises two parts extending generally in the radial direction under the shelf of the first row, so that the longitudinal section of the wall on said shelf has a π-shaped profile.

According to an advantageous embodiment of the present invention, the wall comprises at least one annular stiffener extending inward in the radial direction on the first row of vanes, preferably over at least one of the radial parts.

According to an advantageous embodiment of the present invention, the wall immediately upstream and downstream of the first row comprises a portion with a substantially constant thickness that forms an annular space for accommodating the inner stator housing.

According to an advantageous embodiment of the present invention, the rotor drum comprises blades of a second and / or third row of blades, each of said blades comprising a shank disposed in one or any of the fixing grooves.

According to an advantageous embodiment of the present invention, the locking groove (s) are arranged (arranged) in a ring along the perimeter of the drum.

According to an advantageous embodiment of the present invention, the vanes in the first row and the annular shelf form an integral unit.

According to an advantageous embodiment of the present invention, the drum is made of a metal material, preferably titanium.

According to an advantageous embodiment of the present invention, the wall is forged and processed from a solid body.

According to another advantageous embodiment of the present invention, the annular shelf and the fixing grooves are integrally formed.

According to an advantageous embodiment of the present invention, the drum is characterized by the continuity of the material between the blades of the first row and the wall.

According to an advantageous embodiment of the present invention, the set of annular ribs is axially distributed at the annular joint.

According to an advantageous embodiment of the present invention, all rows of vanes on the drum, with the exception of the first, comprise a groove for fixing the vanes for assembly on the drum.

The present invention also relates to an axial turbomachine comprising a rotor drum, wherein the drum is in accordance with the present invention; preferably, the rotor is a rotor of a low pressure compressor comprising essentially three annular rows of rotor blades.

Advantages of the Invention

It is also an object of the present invention to reduce rotor vibrations of an axial turbomachine. To this end, the freedom of movement between the annular wall and the vanes in the first row is eliminated. The present invention also increases the overall rigidity of the drum. The proposed design also allows to reduce the mass of the rotor, subjecting changes to both the drum and the blades.

The machining of the surfaces of the drum and the blades is simplified. All these improvements to the drum remain possible while maintaining the compatibility of the rotor with the housing formed by the ring stators.

The present invention is applicable to a drum equipped with annular ribs used as sealing elements between compression stages. This aspect is not limiting since the present invention can also be applied to a drum mating with axial brush seals. Such sealing elements are well known to those skilled in the art and, for example, may correspond to the sealing elements disclosed in DE102005042272 A1.

A brief description of the graphic materials

In FIG. 1 shows an axial turbomachine in accordance with the present invention.

In FIG. 2 schematically shows a turbomachine compressor in accordance with the present invention.

In FIG. 3 shows a rotor drum in cross section in accordance with the present invention.

Description of Embodiments

In the following description, the terms “internal” or “inside” or “external” or “external” refer to a position relative to the axis of rotation of the turbomachine.

In FIG. 1 schematically shows an axial turbomachine. In this case, it is a dual-circuit turbojet engine. The turbojet engine 2 contains a first compression stage, the so-called low pressure compressor 4, a second compression stage, the so-called high pressure compressor 6, a combustion chamber 8 and one or more stages of the turbine 10. During operation, the mechanical power of the turbine 10 is transmitted through the central shaft to the rotor 12 and drives two compressors 4 and 6. Reduction mechanisms can increase the speed of rotation transmitted to the compressors. Alternatively, each of the different stages of the turbine can be connected to the stages of the compressor via coaxial shafts. The latter contain several rows of rotor blades connected to the rows of stator blades. The rotation of the rotor around its axis of rotation 14 ensures the creation of a stream and gradually compresses it to the inlet into the combustion chamber 10.

The supply fan, generally designated by the fan 16, is connected to the rotor 12 and creates an air stream divided into a primary stream 18 passing through the various stages of the turbomachine above and a secondary stream 20 passing through an annular channel (partially shown) along the length of the machine, which then connected to the main stream at the outlet of the turbine. The primary stream 18 and the secondary stream 20 are circular flows and are directed through the channels through the turbomachine body. For this purpose, the housing has cylindrical walls or casings, which may be internal or external.

In FIG. 2 shows a sectional view of a compressor of an axial turbomachine 2, such as that shown in FIG. 1. The compressor may be a low pressure compressor 4. The ideas of the present invention also apply to the rotor drum of a turbine 10.

On the compressor 4 there is a front part 22 of the separator of the primary 18 and secondary 20 air flows. The rotor 12 contains several annular rows of rotor blades; in FIG. 2 shows three. Additional rows of vanes may also be provided. These three rows are arranged sequentially in the axial direction. That is, a first row 24 of rotor blades is presented, a second row 26 of rotor blades downstream of the first row 24 and a third row of rotor blades 28 upstream of the first row 24.

The blades (24, 26, 28) of the rotor diverge essentially in the radial direction from the rotor 12. The blades in the same row are located at the same distance from each other and are directed at the same angle into the air stream. Optionally, the distance between the blades may vary in certain places, as well as their angular position. Some shoulder blades in a row may differ from the rest.

Compressor 4 comprises an outer casing. The outer casing contains several stators, for example four, each of which contains an outer casing 30, a row 32 of stator vanes and, optionally, an inner casing 34. An annular layer of abradable material 36 can be applied to the inner surface of the outer casing and the inner stator casing. The blades 32 of the stator of the same stator extend radially from their outer casing 30 to their inner casing 34. The stators form closed circular rings. They are assembled axially opposite each other and are attached to each other using radial flanges 38.

The stators interact with a fan or a row of rotor blades (24, 26, 28) to straighten the air flow so as to convert the flow velocity to pressure.

The rotor 12 comprises a drum 40. The drum 40 comprises a wall 42 generally rotationally symmetrical about its axis of rotation 14, the axis being a common axis for the turbomachine. The wall 42 may have a common rotational profile or a middle rotational profile relative to the axis of rotation 14. The overall profile can be taken into account in the thickness of the parts of the wall 42, which are axially located at right angles to the rows of stator vanes.

The overall profile is generally curved and may have continuous curvature and / or continuously changing curvature. In the radial direction, it coincides with a change in the inner surface of the primary stream 18. The outer surface of the general profile is curved. In the direction from the upstream side to the downstream side, the radius of the inner surface increases and then decreases, so that the wall profile is maximum. Wall 42 is mostly thin. Its thickness is generally constant. Its thickness is less than 10.00 mm, preferably less than 5.00 mm, more preferably less than 2.00 mm. Wall 42 forms a hollow body that forms a cavity that has an animated or barrel shape. Drum 40 and / or rotor blades (24, 26, 28) are made of a metal material, preferably titanium.

Drum 40 comprises annular ribs 44 or sealing lips. They form narrow annular bands that extend in a radial position. They are designed for abrasive mating with the annular layers of abradable material 36, providing a seal. In general, one abradable layer 36 mates with two annular ribs 44.

In FIG. 3 is a detailed sectional view of the drum 40 shown in FIG. 2. The drum may also be the rotor drum of a high pressure compressor. It can also be a turbine rotor drum.

The first row of blades 24 is made integrally on the wall due to the annular shelf 46. The annular shelf 46 is made integrally with the wall 42. The annular shelf 46 is made above the wall profile 42. The annular shelf 46 has a generally straight or curved rotational profile.

Each blade 26 of the rotor of the second row and third row 28 contains a shelf 48 of the blade, forming the inner surface of the primary stream, a blade 50 extending radially outward from the shelf 48 of the blade, and a locking shank 52 extending inward in the radial direction from the shelf 48 of the blade. The locking shank 52 may be in the form of a dovetail. It can have a shape whose axial size increases when approaching inward, providing fixation in place.

The wall 42 of the drum 40 contains two sections for fixing the blades using locking grooves. Each fixation section contains an annular groove 54 into which the fixing shanks 52 of the second row of blades 26 and the third row of blades 28 are inserted. Annular grooves 54 contain annular outer surfaces that come into contact with the shelves 48 of the blades. The shelves 48 of the blades 26 of the second row are engaged with the second outer surface 56, and the shelves 48 of the blades of the third row of blades 28 are engaged with the third outer surface 58.

In general, the shape of the locking shanks 52 coincides with the corresponding locking groove, providing radial fixation. The locking grooves 54 have a profile with a narrowing on the outer surface. Thus, the blades 26 of the second row and the blades 28 of the third row are reversibly fixed. Between the annular wall 42 and the rotor blades of the second and third row, a mechanical clearance is made, providing a slight movement of the blades. However, the rotor is designed in such a way that the centrifugal forces present during compressor operation set the blades in place at their smallest sections.

According to an alternative embodiment of the present invention, the locking grooves may be axial grooves. In this case, the annular wall contains an annular row of axial grooves distributed around its circumference, and each of which forms an annular row of blades.

The outer surface (56, 58) of at least one of the annular grooves 48 is located at an average distance from the axis 14, which is less than the average distance between the annular shelf 46 and the first row 24 of the specified axis. Preferably, each radius at the axial end of the annular shelf 48 is greater than the maximum radius of the outer surface (56, 58) located opposite.

The blades 24 of the first row are attached to the drum in a manner different from the attachment of the blades (26, 28) of the other rows. The fixation or attachment of the blades is different or mixed. The vanes 24 of the first row are attached to the annular shelf 46 by welding. They can be welded by friction, for example, during orbital welding. Thus, the drum 40 serves as a support for fixing the blades of both types.

For this, the blades corresponding to the first row 24 are attached to an unfitted drum and welded to the annular shelf 46. These blades can be directly or indirectly attached to the annular shelf 46. The annular shelf 46 may comprise a blade leg 60 extending radially from its outer surface . In this case, each blade welded to the second surface effectively forms the radial part of the finished blade. A weld 62 between the leg and part of the blade is located above the annular shelf 46.

According to an alternative embodiment of the present invention, the first row of blades 24 can be completely machined on the body of an untreated drum, the wall of which is also machined.

Thus, the wall of the drum 40 and the blades of the first row form a single unit. They are characterized by the continuity of the material. The metallic materials of which they are made have a continuous crystalline structure at their interface. They can be at least partially complete. The fixing of the blades is irreversible. The blades 24 of the first row are made integrally with the annular wall 42. This embodiment eliminates vibrations between the blades 24 of the first row and the wall 42 of the drum 40.

In addition, this method of fixing the blades simplifies the machining, since the manufacture of the annular flange 46 and any leg 60 is simpler than obtaining an annular groove or several axial grooves. Indeed, the groove should be cut as a whole in an inaccessible area with a small tool, which increases the production time. Alternatively, the axial groove may be machined with a broach. However, this method of material removal requires expensive equipment and is not suitable for all types of drums.

The drum wall 42 immediately upstream and downstream of the first row of vanes 24 comprises at least a portion 64 of a substantially constant thickness or an axial annular joint 64 preferably with two parts of a substantially constant thickness 64. Each constant thickness portion 64 extends in the axial direction from the annular shelf 46 to the second row of vanes 26 or to the third row of vanes 28. The annular shelf 46 projects in the radial direction from the portion 64 with a constant thickness. Constant-thickness portions 64 form an annular space between the first row of vanes 24 and the second row of vanes or the third row of vanes 28, with the annular space extending outward in the radial direction. They are designed to accommodate the internal stator housings.

Wall 42 comprises two parts 65 that extend generally in a radial direction. They extend from the ring shelf 46 inward. They can be located on each of the axial edges of the annular shelf 46. Thus, the wall can have a generally π-shaped profile. The profiles of the radial sections extend generally perpendicular to the profile of the annular shelf 46.

The annular ribs 44 are located on parts 64 with a constant thickness. Each set of ribs contains several ribs 44. On each side of the annular flange 46, there is a gradual decrease in the outer radii from the edge of the annular flange 46, the ribs 44, and the outer surfaces (56, 58) of the annular grooves. The tops of these elements form a staircase. This configuration allows the stators equipped with vanes to be fixed on both sides of the first row of vanes 24, and then to assemble the second row 26 and the third row 28.

In FIG. 3 shows the blades 32 and the inner casing 36 of two stators upstream and downstream, respectively, of the first row of blades 24. In FIG. 3 dotted lines also show these stators in an intermediate position during axial assembly around the drum.

The annular wall 42 of the drum contains annular stiffening elements 66. The annular stiffening elements 66 may comprise annular flanges that extend radially inward. These flanges are located in the axial direction at the ends of the annular flange 46, preferably in the radial direction of the radial sections 65.

Typically, the drum is machined by turning, starting with a raw billet in the form of a drum, the walls of which make up the finished drum. The drum blank must radially cover the outer surfaces of the annular grooves 54, the annular shelf 46, the internal stiffeners 66, and any blade leg 60. Depending on the circumstances, it may comprise a first row of vanes 24 over the entire radial height.

Claims (15)

1. The drum (40) of the rotor (12) of the axial turbomachine (2), in particular the low pressure compressor (4), comprising a wall (42) made generally rotationally symmetrical about its axis (14) and having a generally curved profile, while the specified wall (42) is designed to hold several rows (24, 26, 28) of blades,
characterized in that
the first row (24) of blades is formed by an annular shelf (46), made integrally with the wall (42) on the top of its profile relative to the axis (14), at least each blade of one, preferably the second, row (26) of blades located directly downstream from the first (24) and third row (28) of blades located directly upstream from the first (24) row, it is fixed by at least one groove (54) for fixing the blades made on the wall. 2. The rotor drum (40) according to claim 1, characterized in that the outer surfaces (56, 58) of the fixing grooves (54) are located at an average distance from the axis (14), which is less than the average distance from the shelf (46) of the first row ( 24) to the specified axis. 3. The rotor drum (40) according to claim 1, characterized in that the wall (42) on its outer surface comprises a set of annular ribs (44) configured to mate with the annular layer of abradable material (36) to provide a seal, while a set of annular ribs (44) is located in the axial direction between the first (24) and second (26) rows of blades and / or between the first (24) and third (28) rows of blades. 4. The rotor drum (40) according to claim 3, characterized in that the minimum interval between the vertices of one set of ribs (44) relative to the axis (14) is greater than the maximum distance from the specified axis (14) of the outer surfaces (56, 58) of the adjacent fixing groove (grooves) (54). 5. The rotor drum (40) according to claim 1, characterized in that the blades (24) of the first row are welded to the shelf (46) of the indicated row. 6. The rotor drum (40) according to claim 1, characterized in that the shelf (46) of the first row (24) of blades contains legs (60) of the blades to which the blade extensions are welded, preferably the height of the legs (60) of the blades is more than 10% from the radial height of the first row (24) of the blades and more preferably more than 25%. 7. The drum (40) of the rotor according to claim 1, characterized in that the blades (24) of the first row and the wall of the drum 40 are made in one piece. 8. The rotor drum (40) according to claim 1, characterized in that the general curved wall profile (42) extends for the most part of the drum length and / or has a main concavity directed towards the main axis and extending along most of the drum length, wherein the radius of the specified profile relative to the axis is of greatest importance on the first row of blades (24). 9. The rotor drum (40) according to claim 1, characterized in that the shelf (46) of the first row (24) of the blades protrudes relative to the wall immediately above and downstream of the specified row. 10. The rotor drum (40) according to claim 9, characterized in that the wall (42) contains two parts (65) extending generally radially under the shelf (46) of the first row (24), so that the longitudinal section of the wall ( 42) on the indicated shelf (46) has a π-shaped profile. 11. The rotor drum (40) according to claim 10, characterized in that the wall (42) comprises at least one annular stiffener (66) extending inward in the radial direction on the first row (24) of the blades, preferably for at least at least one of the radial parts (65). 12. The rotor drum (40) according to one of claims. 9-11, characterized in that the wall (42) immediately upstream and downstream of the first row (24) contains essentially a portion (64) of constant thickness, which forms an annular space for accommodating the inner casing (34) of the stator. 13. The rotor drum (40) according to claim 1, characterized in that each blade of the second and / or third row of blades contains a shank (52) located in one of the fixing grooves (54). 14. The rotor drum (40) according to claim 1, characterized in that the fixing groove or grooves (54) are located or are arranged along the ring along the perimeter of the drum (40). 15. An axial turbomachine (2) containing a drum (40) of the rotor (12), characterized in that the drum (40) is made according to one of paragraphs. 1-14, while the rotor (12) is preferably the rotor (4) of the low-pressure compressor and contains three annular rows of rotor blades (24, 26, 28).

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