FR3116299A1 - turbomachine compressor - Google Patents

Abstract

A turbomachinery long-axis compressor, comprising a rotor comprising an annular row of moving blades; a stator (140; 240; 340) comprising at least a first annular row of first stationary vanes (142; 242; 342) and a second annular row of second stationary vanes (144; 244; 344), each first stationary vane (142 ; 242; 342) comprising a blade inscribed radially in a first annular space having a first external radius (R1) and a first internal radius (r1), each second fixed vane (144; 244; 344) comprising a blade inscribed radially in a second annular space having a second outer radius (R2) and a second inner radius (r2), the first inner radius (r1) is greater than or equal to the second outer radius (R2), wherein the number of first stationary vanes (142; 242; 342) is different from the number of second fixed vanes (144; 244; 344). Abstract Figure: Figure 3

Description

turbomachine compressor

The present disclosure relates to a turbomachine compressor, in particular an aircraft turbojet or turboprop, and to a turbomachine comprising such a compressor.

Typically, as depicted in , a compressor 10 of a turbomachine such as a turbojet or an airplane turboprop comprises several stages 20 of compression. Each stage 20 comprises a rectifier 40 downstream and a wheel 30 upstream. The wheel 30, or rotor, comprises an annular row of moving blades 32 fixed to a central shaft 14 having an axis of rotation defining a longitudinal axis A1 of the compressor. The stator 40 comprises an annular row of stationary vanes 42 carried externally by an external annular casing 12. In the example of the , the compressor 10 comprises a plurality of stages 20 positioned successively along the longitudinal axis A1, only three stages being shown in FIG. 1.

As illustrated in , the stationary vanes 42 of a stator 40 extend radially between the outer annular casing 12 and an inner shroud 16 fixed to the radially inner end of the stationary vanes 42. The inner shroud 16 has a radially inner face on which rests a abradable material intended to cooperate by friction with wipers of the central shaft 14.

The free spaces, on the one hand between the moving blades 32 of rotor 30, and on the other hand, between the fixed vanes 42 of stator 40, define a vein of the compressor 40.

The moving vanes 32 of the rotor 30 and the fixed vanes 42 of the stator 40 each comprise a blade extending radially inside the vein. The blade of each moving vane and of each fixed vane also has a wing profile shape.

In operation, the central shaft 14 carrying the annular rows of moving blades 32 of the rotor 30 is driven in rotation around the longitudinal axis A1, by means of a turbine. The rotation of each annular row of blades 32 of rotor 30 produces a downstream flow of air in the path of the compressor 10. In particular, the annular row of blades 32 of a rotor 30 produces an increase of the aerodynamic load of the through air flow. The air flow is then then slowed down by being straightened axially by the blades of the stationary vanes 42 of the straightener 40 located downstream of the rotor. The slowing down of the air flow produces an increase in the pressure of the air flow at the outlet of the rectifier 40. Thus, the air flow is gradually compressed by flowing through the successive 20 stages of the compressor 10.

The ability of a stator 40 to slow down and straighten an airflow having a given aerodynamic load is a function of the relative circumferential pitch between the blades of two adjacent stationary vanes 42 of the stator 40. Thus, the number of stationary vanes 42 d a rectifier is determined according to the aerodynamic load of the air flow entering the rectifier.

However, the aerodynamic load of the airflow varies radially in the vein. For example, an aerodynamic load of the airflow in the vicinity of the radially inner end of the vane blades 42 of the stator 40 can be less than an aerodynamic load of the airflow in the vicinity of the radially outer end of the blades.

Therefore, the number of fixed vanes 42 is generally selected as being as high as possible to allow straightening and sufficient slowing down of the air flow over the entire radial dimension of the vein.

Nevertheless, such a rectifier 40, having a constant number of fixed vanes 42 over the entire radial dimension of the vein, has the disadvantage of not producing an optimal straightening and slowing down of the air flow on the entire radial dimension of the vein. In addition, the excess of stationary vanes 42 increases the mass of the compressor 10 and produces pressure drops due to the friction of the air flow on the blades of the stationary vanes 42, thus reducing the efficiency of the compressor 10.

Summary

A turbomachine longitudinal axis compressor is proposed, the compressor comprising:
- a rotor comprising an annular row of moving blades,
- a straightener mounted downstream of the annular row of moving vanes and comprising at least a first annular row of first stationary vanes and a second annular row of second stationary vanes, each first stationary vane comprising a blade inscribed radially in a first annular space having a first external radius and a first internal radius, each second fixed vane comprising a blade inscribed radially in a second annular space having a second external radius and a second internal radius,
wherein the first inner radius of said first annular space is greater than or equal to the second outer radius of said second annular space,
wherein the number of first stationary vanes is different from the number of second stationary vanes.

The number of first stationary vanes of the first annular row is thus adjusted to the aerodynamic load of the air flow entering the stator in the vicinity of the first annular space. Likewise, the number of second stationary vanes of the second annular row can be adjusted to the aerodynamic load of the air flow entering the rectifier in the vicinity of the second annular space. Thus, advantageously, the straightening and slowing down of the flow of air by the rectifier is improved.

The same plane transverse to the longitudinal axis can intercept the first fixed vanes and the second fixed vanes.

The first annular space may be bounded, upstream, by a leading edge of each first fixed vane and, downstream, by a trailing edge of each first fixed vane. The second annular space can be bounded, upstream, by a leading edge of each second fixed vane and, downstream, by a trailing edge of each second fixed vane. The first annular space and the second annular space may have the same longitudinal dimension. An upstream end of the first annular space and an upstream end of the second annular space may be at the same longitudinal position. A downstream end of the first annular space and a downstream end of the second annular space can be at the same longitudinal position.

A radially outer end of each first stationary vane of the stator can be attached to an outer annular casing.

A radially inner end of each second stationary vane of the stator can be attached to an inner shroud.

The number of first stationary vanes may be less than the number of second stationary vanes.

Thus, the straightening and slowing down of the flow of air by the straightener is improved in the case where the flow of air presents a higher aerodynamic load at the level of a radially internal portion of the vein than at the level of a radially outer portion of the vein. The reduction in the number of first stationary vanes of the first annular row also makes it possible to reduce the mass of the stator and to limit frictional pressure drops.

A radially inner end of each first stationary vane and/or a radially outer end of each second stationary vane can be fixed to an intermediate shroud.

Such an arrangement allows a better mechanical strength of the stator, it allows in particular to limit the vibrations undergone by the first and second fixed blades.

Each first stationary vane can be cantilevered at a radially inner end and each second stationary vane can be cantilevered at a radially outer end.

In other words, the rectifier may have no intermediate shroud. Such an arrangement makes it possible to limit the mass of the rectifier. Furthermore, this arrangement makes it possible to limit the pressure losses by friction, in comparison with an arrangement comprising an intermediate shroud between the first and second annular rows of fixed blades.

The stator may comprise a third annular row of third fixed vanes, each third fixed vane comprising a blade inscribed radially in a third annular space having a third external radius and a third internal radius, in which the third internal radius of said third annular space is greater or equal to the second outer radius of said second annular space, the third outer radius of said third annular space being less than or equal to the first inner radius of said first annular space, wherein the number of third stationary vanes may be different from the number of first stationary vanes and /or the number of second fixed vanes.

The number of third fixed blades of the third annular row can also be adjusted to the aerodynamic load of the air flow entering the rectifier in the vicinity of the third annular space. A third annular row of fixed blades thus allows a more precise adjustment of the number of blades to the radial variation of the aerodynamic load.

Said plane transverse to the longitudinal axis can also intercept the third fixed vanes.

The third annular space may be bounded, upstream, by a leading edge of each third fixed vane and, downstream, by a trailing edge of each third fixed vane. The third annular space may have the same longitudinal dimension as the first annular space and the second annular space. An upstream end of the third annular space may be at the same longitudinal position as an upstream end of each of the first annular space and the second annular space. A downstream end of the third annular space may be at the same longitudinal position as a downstream end of each of the first annular space and the second annular space.

The rectifier may comprise a plurality of sectors arranged circumferentially end to end around the longitudinal axis.

Such an arrangement makes it possible to improve the manufacture and the associated cost of the rectifier.

The rectifier can be one-piece.

Such an arrangement allows simpler mounting of the rectifier in the compressor.

A turbomachine, such as a turbojet or a turboprop, may be proposed, comprising a compressor according to any one of the preceding claims.

Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the appended drawings, in which:

, already described previously, represents a partial schematic half view in axial section of a compressor of the prior art;

, already described above, is a perspective view of the rectifier of the compressor of the ;

is a perspective view of a compressor rectifier according to a first embodiment;

is a partial perspective view of a compressor rectifier according to a second embodiment;

is a perspective view of a compressor rectifier according to a third embodiment.

There shows a first example of a rectifier 140 for a turbomachine compressor with a longitudinal axis (A1). This is a 140 rectifier for an axial compressor. The rectifier is intended to be mounted downstream of a moving blade wheel, thus forming a stage of the compressor. The moving blade wheel is driven in rotation around the longitudinal axis by means of a central shaft extending along the longitudinal axis. The central shaft can, for example, be connected to a turbine of the turbomachine. A compressor stage, comprising such a rectifier 140, is in particular suitable for compressing a primary flow of a bypass turbomachine.

The compressor comprises an outer annular casing 112. A portion of the outer annular casing 112, surrounding the rectifier 140, is visible in .

The stator 140 comprises a first annular row of first stationary vanes 140. Each first stationary vane 140 of the stator is fixed, at a radially outer end, to the outer annular casing 112.

The stator 140 also comprises a second annular row of second stationary vanes 144. Each second stationary vane 144 of the stator is fixed here, at one radially inner end, to an inner shroud 116. Here and in what follows, the term "shroud" refers to an annular part. The inner shroud 116 is adapted to surround the central shaft of the compressor. To this end, a radially internal surface of the shroud carries an abradable material intended to cooperate by friction with wipers of the central shaft to limit an exit of the air from the vein of the compressor.

Each first stationary vane 144 comprises a blade inscribed radially in a first annular space having a first external radius R1 and a first internal radius r1. The first annular space is here delimited radially on the outside by the external annular casing 112. Thus, the first external radius R1 corresponds to the radius of the portion of the external annular casing 112 in the vicinity of the rectifier 140.

Similarly, each second fixed vane 144 comprises a blade inscribed radially in a second annular space having a second external radius R2 and a second internal radius r2. The second annular space is delimited radially on the inside by the internal shroud 116. Thus, the second internal radius r2 corresponds to the radius of the internal shroud 116 of the rectifier 140.

The blades of the first stationary vanes 142 and of the second stationary vanes 144 here have identical geometric parameters. For example, the blades of the first stationary vanes 142 and of the second stationary vanes 144 have the same chord and the same angle of attack. Alternatively, the blades of the first stationary vanes 142 and of the second stationary vanes 144 may have different geometric parameters.

Remarkably, the first annular row of first stationary vanes 142 surrounds the second annular row of second stationary vanes 144. In other words, the first internal radius r1 of the first annular space is greater than or equal to the second external radius R2 of the second annular space. A same plane transverse to the longitudinal axis intercepts the first fixed vanes 142 and the second fixed vanes 144. The first annular space is bounded, upstream, by a leading edge of each first fixed vane 142 and, at the downstream, by a trailing edge of each first fixed vane 142. The second annular space is bounded, upstream, by a leading edge of each second fixed vane 144 and, downstream, by an edge of leakage of each second fixed vane 144. The first annular space and the second annular space have the same longitudinal dimension. An upstream end of the first annular space and an upstream end of the second annular space are at the same longitudinal position. A downstream end of the first annular space and a downstream end of the second annular space are at the same longitudinal position.

According to the first embodiment of the , the first stationary vanes 142 are cantilevered at a radially inner end. In other words, a radially inner end of each first fixed vane 142 is free. Likewise, the second stationary vanes 144 are cantilevered at a radially outer end. Alternatively, a radially outer end of each second fixed vane 144 is free. Thus, the rectifier 140 has no intermediate shroud between the first annular row and the second annular row, as will be described later. Such an arrangement makes it possible to limit the mass of the stator 140. Furthermore, this arrangement makes it possible to limit the pressure losses by friction in comparison with an arrangement comprising an intermediate shroud between the first and second annular rows of fixed vanes 142, 144.

The inner shroud 116 can then be connected to the outer annular casing 112 by arms extending radially between the inner shroud 116 and the outer annular casing 112. For example, the rectifier 140 can comprise three arms securing the inner shroud 116 to the annular casing external 112.

In addition, the number of first stationary vanes 142 is different from the number of second stationary vanes 144. Indeed, the number of first stationary vanes 142 and second stationary vanes 144 are independent of each other. Also, the choice of the number of fixed vanes per annular row makes it possible to modify, between the first annular space and the second annular, the solidity of the stator, the solidity being defined by the ratio between the chord of the blades and the pitch between two blades. adjacent to an annular row.

The number of stationary vanes per annular row of the stator is then to be adjusted according to the radial variation of the aerodynamic load of the air flow entering the stator and according to a desired deviation of the air flow. Thus, the straightening and slowing of the air flow by the rectifier is improved.

To do this, the number of first stationary vanes 142 is here adjusted to the aerodynamic load of the air flow entering the rectifier 140 at the level of the first annular space. Likewise, the number of second fixed vanes 144 of the second annular row is adjusted to the aerodynamic load of the air flow entering the rectifier 140 at the level of the second annular space.

In the example shown in , the number of first stationary vanes 142 is less than the number of second stationary vanes 144. Such an arrangement is particularly suitable for an airflow having a higher aerodynamic load at the level of a radially internal portion of the vein than at the level of a radially external portion of the vein. Indeed, the number of stationary vanes necessary for straightening and slowing down the air flow is all the lower as the aerodynamic load of the air flow is high.

The reduction in the number of first stationary vanes 142 makes it possible to limit the pressure losses by friction of the air flow on the blades of the first stationary vanes 142. Thus, the efficiency of the rectifier 140 is improved. In addition, this makes it possible to reduce the mass of the rectifier 140.

In addition, the increase in the number of second fixed vanes 144 compared to the number of first fixed vanes 142 makes it possible to limit, or even prevent, the separation of the air flow on the blades.

The rectifier 140 is here in one piece. Nevertheless, the rectifier 140 may comprise a plurality of sectors arranged circumferentially end to end around the longitudinal axis. For example, the rectifier 140 may comprise two sectors having the shape of semicircles.

There represents a second exemplary embodiment of the stator 240. The second exemplary embodiment differs from the first exemplary embodiment in that the stator 240 comprises an intermediate shroud 252. Each first stationary vane 242 is then fixed, at the radially inner end, to the intermediate shroud 252. Similarly, each second fixed vane 244 is fixed, at the radially outer end, to the intermediate shroud 252.

Thus, the first internal radius r1 of the first annular space here corresponds to an external radius of the intermediate shroud 252. The second external radius R2 of the second annular space corresponds to an internal radius of the intermediate shroud 252.

Such an intermediate shroud 252 allows a better mechanical resistance of the rectifier 240, in particular by limiting the vibrations undergone by the first and second fixed vanes 242, 244.

Alternatively, only the stationary vanes 242, 244 of one of the first and second annular rows can be fixed to the intermediate shroud 252.

There shows a third exemplary embodiment of a stator 340. The third exemplary embodiment differs from the second exemplary embodiment essentially in that the stator 340 comprises a third annular row, the third annular row comprising third stationary vanes 346. Each third stationary vane 346 comprises a blade inscribed radially in a third annular space having a third external radius R3 and a third internal radius r3.

The third annular row is here inserted radially between the first annular row and the second annular row. In other words, the third internal radius r3 of the third annular space is greater than or equal to the second external radius R2 of the second annular space and the third external radius R3 of the third annular space is less than or equal to the first internal radius r1 of the first space annular.

The plane transverse to the longitudinal axis, intercepting the first stationary vanes 342 and the second stationary vanes 344, also intercepts the third stationary vanes 346. The third annular space is bounded, upstream, by a leading edge of each third fixed vane 346 and, downstream, by a trailing edge of each third fixed vane 346. The third annular space has the same longitudinal dimension as the first annular space and the second annular space. An upstream end of the third annular space is at the same longitudinal position as an upstream end of each of the first annular space and the second annular space. A downstream end of the third annular space is at the same longitudinal position as a downstream end of each of the first annular space and the second annular space.

The rectifier 340 comprises a first intermediate shroud 354. Each first fixed vane 342 is fixed, at the radially inner end, to the first intermediate shroud 354. Each third fixed vane 346 is fixed, at the radially outer end, to the first intermediate shroud 354. Thus, the first internal radius r1 of the first annular space here corresponds to an external radius of the first intermediate shroud 354. The third external radius R3 of the third annular space corresponds to an internal radius of the first intermediate shroud 354.

The rectifier 340 comprises a second intermediate shroud 356. Each third fixed vane 346 is fixed, at the radially inner end, to the second intermediate shroud 356. Each second fixed vane 344 is fixed, at the radially outer end, to the second intermediate shroud 356. Thus, the third internal radius r3 of the third annular space here corresponds to an external radius of the second intermediate shroud 356. The second external radius R2 of the second annular space corresponds to an internal radius of the second intermediate shroud 356.

Remarkably, the number of third fixed vanes 346 is different from the number of first fixed vanes 342. The number of third fixed vanes 346 is, here also, different from the number of second fixed vanes 344.

The number of third fixed vanes 346 of the third annular row is adjusted to the aerodynamic load of the air flow entering the rectifier 340 in the vicinity of the third annular space. A third annular row of stationary vanes 346 thus allows a more precise adjustment of the number of stationary vanes per annular row according to the radial variation of the aerodynamic load.

In the third embodiment of the , the number of second stationary vanes 344 is greater than the number of third stationary vanes 346, the latter being greater than the number of first stationary vanes 342. Similarly to the first example embodiment, the rectifier 340 of the third example embodiment is in particular adapted to an airflow whose aerodynamic load increases radially outwards in the compressor channel.

The invention is not limited to the examples described above and is capable of numerous variants.

According to a variant not shown of the first and of the second embodiment, the number of first fixed vanes 142, 242 is greater than the number of second fixed vanes 144, 244.

According to variants not shown of the third embodiment, all combinations of relationships between the numbers of first, second and third fixed blades 342, 344, 346 are possible.

According to a variant of the third embodiment, not shown, the stationary vanes of two annular rows can be cantilevered, so that the stator 340 only comprises a single intermediate shroud.

According to another variant not shown, the stator comprises more than three annular rows of stationary vanes.

According to a variant not shown, the rectifier is a compressor rectifier of the centrifugal or mixed type, that is to say of the axial and centrifugal type.

Claims (10)

A turbomachine longitudinal axis compressor, the compressor comprising:
- a rotor comprising an annular row of moving blades,
- a straightener (140; 240; 340) mounted downstream of the annular row of moving vanes and comprising at least a first annular row of first stationary vanes (142; 242; 342) and a second annular row of second stationary vanes ( 144; 244; 344), each first fixed vane (142; 242; 342) comprising a blade inscribed radially in a first annular space having a first external radius (R1) and a first internal radius (r1), each second fixed vane ( 144; 244; 344) comprising a blade inscribed radially in a second annular space having a second external radius (R2) and a second internal radius (r2), in which the first internal radius (r1) of said first annular space is greater than or equal at the second outer radius (R2) of said second annular space, wherein the number of first stationary vanes (142; 242; 342) is different from the number of second stationary vanes (144; 244; 344). A compressor according to claim 1, wherein a radially outer end of each first stationary vane (142; 242; 342) of the stator (140; 240; 340) is fixed to an outer annular casing (112; 212; 312). A compressor according to claim 1 or 2, wherein a radially inner end of each second stationary vane (144; 244; 344) of the stator (140; 240; 340) is attached to an inner shroud (116; 216; 316). A compressor according to any preceding claim, wherein the number of first stationary vanes (142; 242; 342) is less than the number of second stationary vanes (144; 244; 344). Compressor according to any one of the preceding claims, in which a radially inner end of each first stationary vane (242; 342) and/or a radially outer end of each second stationary vane (244; 344) is fixed to an intermediate shroud ( 252; 354; 356). A compressor according to any one of claims 1 to 4, wherein each first stationary vane (142) is cantilevered at a radially inner end and each second stationary vane (144) is cantilevered at a radially outer end. A compressor according to any preceding claim, wherein the stator (340) comprises a third annular row of third fixed vanes (346), each third fixed vane (346) comprising a blade inscribed radially in a third annular space having a third outer radius (R3) and a third inner radius (r3), wherein the third inner radius (r3) of said third annular space is greater than or equal to the second outer radius (R2) of said second annular space, the third outer radius (R3) said third annular space being less than or equal to the first internal radius (r1) of said first annular space, wherein the number of third stationary vanes (346) is different from the number of first stationary vanes (342) and/or the number of second vanes fixed (344). A compressor according to any preceding claim, wherein the rectifier (140; 240; 340) comprises a plurality of sectors arranged circumferentially end to end around the longitudinal axis. Compressor according to any one of claims 1 to 7, in which the rectifier (140; 240; 340) is integral. A turbomachine, such as a turbojet or a turboprop, comprising a compressor according to any preceding claim.