KR101401328B1 - An apparatus for stall suppression of an axial compressor by casing treatment - Google Patents

Abstract

The present invention relates to an apparatus for suppressing the stall of an axial compressor using a casing treatment.
In order to achieve the above object, an apparatus for suppressing stall of an axial compressor using a casing treatment according to an embodiment of the present invention is characterized in that in an axial compressor having an outer casing in which a groove is formed in an inner wall opposed to a rotor, An inner casing which is movable in the axial direction of the outer casing so as to open the groove of the outer casing in an unstable operating region and to close the groove of the outer casing in a stable operating region; And driving means for moving the casing in the axial direction of the outer casing.
Accordingly, the present invention can be applied not only to a casing treatment structure in which the slope of the groove does not change according to the rotation position of the rotor but also to a casing having various types of grooves such as a radial slot or an axial skewed slot have.

Description

[0001] The present invention relates to a stall suppression device for an axial compressor,

The present invention relates to an apparatus for suppressing the stall of an axial compressor using a casing treatment.

A compressor used as a main component of aircraft engines and industrial gas turbines is composed of several rotating blades and serves to suck and compress air. In order to maximize the pressure ratio or efficiency of each stage in relation to such a compressor, active research has been conducted.

However, the unstable flow structure such as a stall or a surge in the compressor occurs due to an unexpected situation in the vicinity of the operating point at which high pressure and efficiency can be obtained, resulting in a deterioration in performance of the entire system A case occurs. For example, in an aircraft engine, when the pressure of the compressor outlet becomes excessively high during the operation of the compressor, the air moves away from the blade surface at the compressor inlet and enters a stall phenomenon that causes instability of the entire engine or compressor system .

There are active control and passive control methods for stall suppression. Typical active control schemes are to suppress the stall of the compressor, Pressure air is injected in the vicinity of the end, and in the manual control method, various shapes of concavities and convexities such as grooves and slots are formed in the compressor casing, that is, through the casing treatment, There is a method in which the operation region is widened by restraining or delaying the occurrence of stall by recirculating the high-pressure air to the upstream.

However, the former is capable of suppressing the stall without reducing the efficiency, but has a drawback in that it is expensive and difficult to apply to a high-speed compressor. Also, in the latter case, it can be easily applied to a compressor, and it is helpful to improve the stability of operation due to stall generation delay, but it has a problem that the efficiency of the compressor is deteriorated in order to suppress the stall, thereby adversely affecting the performance of the compressor.

Particularly, in order to solve the latter problem, as shown in FIG. 4, Korean Patent No. 10-1025857 discloses a 'fluid stabilizing device for a axial flow impeller'. The apparatus of the Korean patent is provided with a driving unit 700 for each section divided in the circumferential direction of the case 500. Each of the driving units 700 moves in the radial direction of the case 500 And the rib 620 is inserted into the adjustment hole 610. Specifically, the case 500 is divided into four sections, and then the driving section 700 is disposed for each section. Particularly, in the interval I, the control hole 610 is at 12 o'clock. In the interval II, the control hole 610 is at 3 o'clock. In the interval III, the control hole 610 is at 6 o'clock. 610 are formed uniformly at 9 o'clock direction, respectively. That is, the moving direction of the driving unit 700, the inclination direction of the adjusting hole 610, and the direction of the adjusting rib 620 must all coincide with each other.

Therefore, assuming that the rotation direction of the rotor is clockwise, when the blade (the rotor) exits the section I from the 12 o'clock direction of the section I, the inclination direction of the control hole 610 l is tilted in a direction opposite to the direction of rotation of the blades so that the flow does not flow into the control hole 610 or decreases so that the downstream air can not be guided to the upstream side and consequently the downstream high pressure air is recycled to the upstream side There is a problem that the effect of suppressing or delaying the occurrence of stall is deteriorated. In addition, when the radius of the case is taken as a reference, the inclination of the adjusting hole 610, which is opposite to the blade edge of the blade, changes according to the rotational position of the blade, which may adversely affect the overall stability of the axial compressor.

Korean Patent No. 10-1025857 (Published on Mar. 30, 2011)

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus for restraining a stall of an axial compressor using a casing treatment that does not impair performance such as compressor efficiency while suppressing occurrence of instability such as stall occurrence .

It is also an object of the present invention to provide an apparatus for suppressing stall of an axial compressor using a casing treatment, which can be applied to a casing treatment structure in which the slope of the groove is not changed according to the rotational position of the rotor.

Further, the present invention includes other objects that can be achieved from the construction of the present invention described later, in addition to the objects explicitly mentioned.

According to an aspect of the present invention, there is provided an apparatus for suppressing a stall of an axial compressor using a casing treatment, the apparatus comprising: an axial compressor including an outer casing having a groove formed in an inner wall facing the rotor, An inner casing movable in the axial direction of the outer casing so as to open or close the groove of the outer casing; and drive means for moving the inner casing in the axial direction of the outer casing .

The outer casing may include a cavity communicating with the groove in the axial direction of the outer casing and located inside the outer casing, and a slot communicating with the cavity in the thickness direction of the outer casing, ).

Further, the driving means includes a connecting member connected to the inner casing and extending to the outside through the slot, and a moving means for moving the connecting member in an axial direction of the outer casing.

The moving means includes a cylinder connected to the connecting member, the cylinder being divided into right and left through an inner portion of the partition, a first valve controlling the inflow of high pressure air located downstream of the axial compressor into the cylinder, And a third valve and a fourth valve for controlling the flow of the high-pressure air introduced into the cylinder.

The first valve and the third valve are connected to the left side of the cylinder, and the second valve and the fourth valve are connected to the right side of the cylinder.

Further, a distance between a portion where the groove and the cavity communicate with each other in the outer casing is equal to a thickness of the inner casing.

A hermetic holding member is mounted between the outer casing and the inner casing at a portion where the groove and the cavity communicate with each other.

Further, the inner casing moves in such a manner that the groove is opened in an unstable operating region and the groove is closed in a stable operating region.

According to the present invention having the above-described configuration, when the compressor is operated in a region far from the stall, the casing treatment is closed, and if the operating point approaches the stall, the casing treatment is opened to expand the operating point, The stall can be suppressed without reduction and the operation range can be expanded.

Further, the present invention can be applied not only to a casing treatment structure in which the inclination of the groove does not change according to the rotational position of the rotor but also to casings having various types of grooves such as a radial slot or an axial skewed slot .

Further, when necessary, the casing treatment formed on the outer casing can be easily opened and closed through the inner casing and the driving means for driving the inner casing.

Further, by utilizing high-pressure air downstream of the compressor for driving the inner casing, the inner casing can be effectively moved in the axial direction of the compressor without requiring a separate driving energy source.

On the other hand, the effects of the present invention are not limited to those described above, and other effects that can be derived from the constitution of the present invention described below are also included in the effects of the present invention.

Fig. 1 shows an example of a compressor in which a casing treatment is formed on an outer casing.
FIG. 2 is a cross-sectional view taken along the line AA of FIG. 3 showing a main configuration of a stall restraining device for an axial compressor using a casing treatment according to an embodiment of the present invention.
3 is a perspective view of a main structure showing a stall restraining device of the axial compressor of Fig. 2 mounted on an outer casing.
4 shows a fluid stabilizing device of a conventional axial compressor.

Hereinafter, a stall restraining device for an axial compressor (hereinafter referred to as a stall restraining device of the present axial compressor) utilizing a casing treatment according to an embodiment of the present invention will be described in detail with reference to the drawings.

First, referring to FIG. 1, an axial compressor will be briefly described. The axial compressor includes a rotary part 400 and an outer casing 300. The rotary part 400 includes a rotary shaft 401 and a plurality of blades 402 arranged in the circumferential direction of the rotary shaft 401. The outer casing 300 is provided with a plurality of stator blades 302 corresponding to the rotor 402. The fluid introduced into the compressor is compressed and discharged after passing between the rotating rotor 402 and the stationary stator 302.

However, an axial compressor can cause a stall due to an unexpected situation in a low flow rate and high pressure section having a high efficiency. In order to prevent this, a casing treatment 301 may be provided in the outer casing 300, but this has a disadvantage that the performance of the compressor is adversely affected, such as the efficiency of the compressor being reduced.

The present invention can easily open and close a casing treatment formed on an outer casing to suit the situation, thereby enabling stall prevention and compressor efficiency to be maintained at the same time, and being applicable to casings having various types of grooves .

2 and 3, the stall restraint device of the present axial compressor is provided with an axial compressor (not shown) having an outer casing 3 in which a groove (casing treatment) 31 is formed on an inner wall facing the rotor 402, And includes, as main components thereof, an inner casing 1 and a driving means 2 for driving the inner casing 1. [

The inner casing 1 is located inside the outer casing 3 and opens the groove 31 of the outer casing 3 in an unstable operating region and the groove 31 of the outer casing 3 in a stable operating region, In the axial direction of the outer casing (3).

On the other hand, the outer casing 3 has a cavity 32 communicating with the groove 31 in the axial direction of the outer casing and located inside the outer casing 3. Here, the inside of the outer casing 3 means that the cavity 32 is located between the inner wall and the outer wall of the outer casing 3, and through which the cavity 32 is connected to the working fluid passing through the compressor And is not exposed to the outside except for the slot 33 which will be described later.

The outer casing 3 also has a slot 33 communicating with the cavity 32 in the wall thickness direction of the outer casing.

The driving means 2 moves the inner casing 1 in the axial direction of the outer casing 3 and includes a connecting member 21 connected to the inner casing 1 and extending outward through the slot 33, And a moving means (22) for moving the connecting member (21) in the axial direction of the outer casing (3).

Specifically, the moving means 22 is connected to the connecting member 21 and includes a cylinder 221 whose inside is divided into right and left through a partition wall, a cylinder 221 which can control the inflow of high pressure air downstream of the axial compressor into the cylinder 221 A first valve 222 and a second valve 223 and a third valve 224 and a fourth valve 225 capable of regulating the flow of the high pressure air introduced into the cylinder 221. Of course, the moving means 22 may use a known hydraulic device in addition to this. For example, hydraulic pressure may be used from a hydraulic device mounted on an aircraft engine.

The connecting member 21 includes a first connecting member 211 connected to the inner casing 1 and a second connecting member 211 connected to both ends of the first connecting member 211 and the cylinder 221, 212). For reference, as shown in FIG. 2, the second connecting member 212 may be disposed parallel to the compressor axial direction, and the first connecting member 211 may be disposed perpendicular to the compressor axial direction.

Hereinafter, the operation (operation) of the stall restraint device of this axial-flow compressor having such a configuration will be described.

First, in the operating region where the operating point of the compressor is approaching the stall, the inner casing 1 is moved in the downstream direction of the working fluid (rightward in FIG. 2) so that the grooves 31 of the outer casing 3 are exposed to the working fluid ). ≪ / RTI > The first valve 222 and the fourth valve 225 are opened in the drive means 2 and the second valve 223 and the third valve 224 are closed to introduce high pressure air into the left side of the cylinder 221 .

The connecting member 21 is moved in the downstream direction of the working fluid and the inner casing 1 connected to the connecting member 21 is also moved in the downstream direction of the working fluid, . At this time, the casing groove 31 is exposed to the working fluid, and the high-pressure air downstream in the casing groove 31 is recirculated to the upstream side, thereby restraining the stall, thereby widening the operating range.

On the other hand, the inner casing 1 is formed so that the working fluid flowing into the casing groove 31 flows from the outer casing 3 to the outer casing 3 so as not to flow into the cavity 32 through the gap between the inner casing 1 and the outer casing 3 It is preferable that the gap g (the thickness direction of the outer casing) of the portion where the groove 31 and the cavity 32 communicate with each other matches the wall thickness of the inner casing 1. The meaning of the distance g between the communicating portions and the thickness of the wall of the inner casing 1 means that the gap between the inner casing 1 and the outer casing 3 is closed g and the wall thickness of the inner casing 1 are not substantially different from each other. A known airtightness holding member such as a seal may be additionally installed between the inner casing 1 and the outer casing 3 at a portion where the groove 31 of the outer casing communicates with the cavity 32 will be.

Next, when the operation point of the compressor is operated in a stable region considerably distant from the stall, the groove 31 of the outer casing 3 needs to be not exposed to the working fluid.

To this end, the second valve 223 and the third valve 224 are opened to move the inner casing 1 in the upstream direction (left direction of FIG. 2) of the working fluid, and the first valve 222 and the fourth valve (225) is closed to introduce high-pressure air to the right side of the cylinder (221). The connecting member 21 moves in the upstream direction of the working fluid and the inner casing 1 connected to the connecting member 21 moves in the upstream direction of the working fluid while the inner casing 1 moves to the outer casing 3 in a direction away from the cavity 32. At this time, the casing groove 31 is closed so as not to be exposed to the working fluid, thereby preventing the performance of the compressor efficiency from being reduced.

On the other hand, as described above, the operating region where instability occurs in which the operating point of the compressor approaches the stall occurs and the stable region in which the operating point of the compressor is considerably distanced from the stall can be preset in advance through experimental data or the like.

As described above, in the related art, the structure can be applied only when the moving direction of the driving unit 700, the inclination direction of the adjusting hole 610, and the direction of the adjusting rib 620 are all the same, The stall restraining device of the present axial compressor can be applied to a constant casing without changing the inclination of the groove in the circumferential direction, while the stall restraint device of this axial compressor can be applied only to the casing 500 in which the inclination l changes in the circumferential direction. As a result, the tilting direction of the grooves is formed opposite to the direction of rotation of the blades, so that the flow does not flow into the grooves, and the downstream air can not be guided to the upstream side, thereby reducing the effect of suppressing or delaying stall occurrence. The problem of the stall restraining device of the present axial compressor can be improved. Further, the stall restraining device of the present axial compressor can be applied to a casing having a constant groove inclination according to the rotational position of the rotor, thereby contributing to an improvement in the overall stability of the axial compressor.

While the present invention has been particularly shown and described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, And all changes and modifications to the scope of the invention.

1 ... inner casing,
2 ... driving means,
21 ... connection member, 211 ... first connection member
212 ... second connecting member, 22 ... moving means
221 ... cylinder, 222 ... first valve
223 ... second valve,
3 ... outer casing,
31 ... groove, 32 ... cavity,
33 ... slot

Claims (8)

An apparatus for suppressing the occurrence of stall in an axial compressor having an outer casing having a groove formed in an inner wall facing a rotor,
An inner casing movable in the axial direction of the outer casing to open or close the groove of the outer casing;
A drive means for moving the inner casing in the axial direction of the outer casing
/ RTI >
The outer casing
A cavity communicating with the groove in an axial direction of the outer casing and located inside the outer casing,
A slot communicating with the cavity in the thickness direction of the outer casing;
/ RTI >
Wherein an interval of a portion where the groove and the cavity communicate with each other in the outer casing is equal to a thickness of the inner casing
An apparatus for suppressing stall of an axial compressor using a casing treatment. delete The method of claim 1,
The driving means includes:
A connecting member connected to the inner casing and extending to the outside through the slot, and
A moving means for moving the connecting member in an axial direction of the outer casing,
Containing
An apparatus for suppressing stall of an axial compressor using a casing treatment. 4. The method of claim 3,
The moving means
A cylinder connected to the connecting member and having an interior partitioned into left and right through a partition wall,
A first valve and a second valve for regulating introduction of high-pressure air located downstream of the axial compressor into the cylinder,
A third valve for controlling the outflow of the high-pressure air introduced into the cylinder,
Having a
An apparatus for suppressing stall of an axial compressor using a casing treatment. 5. The method of claim 4,
Wherein the first valve and the third valve are connected to the left side of the cylinder and the second valve and the fourth valve are connected to the right side of the cylinder. delete The method of claim 1,
And a hermetic holding member is mounted between the outer casing and the inner casing at a portion where the groove and the cavity communicate with each other. The method of claim 1,
Wherein the inner casing moves in such a manner that the groove is opened in an unstable operating region and the groove is closed in a stable operating region.

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