阅读说明：本技术 压气机控制 (Compressor control ) 是由 S·克里施纳巴布 于 2018-12-12 设计创作，主要内容包括：一种用于燃气涡轮发动机(10)的控制器(300),该控制器根据一种控制方法进行操作。燃气涡轮发动机(10)包括具有壳体(50)的压气机(14),壳体沿操作轴线(20)延伸并且中心在操作轴线上。压气机动叶的阵列(48)被耦接到沿操作轴线(20)延伸的可旋转发动机轴(22)。第一可变导流静叶(8a)沿着操作轴线(20)与压气机动叶阵列(48)轴向间隔开,其中第一可变导流静叶(8a)可旋转地安装在壳体(50)上的第一位置(202)处,具有与操作轴线(20)成直角的静叶旋转轴线(121)。第一可变导流静叶(8a)可以耦接至调节驱动器(154),该调节驱动器可操作以使第一可变导流静叶(8a)绕第一可变导流静叶的旋转轴线(121)旋转到相对于操作轴线(20)的一个角度范围(A-D)。控制器(300)能够可操作以根据发动机轴速度来控制第一可变导流静叶(8a)的旋转,其中在发动机轴速度的第一范围(A-B)内,第一可变导流静叶(8a)相对于操作轴线(20)的角度随着发动机速度的增加而减小,并且在发动机轴速度的第二范围(B-C)内,第一可变导流静叶(8a)相对于操作轴线(20)的角度随着发动机速度的增加而增加。(A controller (300) for a gas turbine engine (10) operates according to a control method. The gas turbine engine (10) includes a compressor (14) having a casing (50) extending along and centered on an operating axis (20). An array (48) of compressor blades is coupled to a rotatable engine shaft (22) extending along an operational axis (20). The first variable guide vane (8a) is axially spaced from the compressor blade array (48) along an operational axis (20), wherein the first variable guide vane (8a) is rotatably mounted at a first location (202) on the casing (50) with a vane rotational axis (121) at right angles to the operational axis (20). The first variable guide vane (8a) may be coupled to an adjustment drive (154) operable to rotate the first variable guide vane (8a) about a rotational axis (121) of the first variable guide vane to an angular range (a-D) relative to the operational axis (20). The controller (300) is operable to control rotation of the first variable guide vane (8a) as a function of engine shaft speed, wherein over a first range of engine shaft speeds (a-B) the angle of the first variable guide vane (8a) relative to the operating axis (20) decreases with increasing engine speed, and over a second range of engine shaft speeds (B-C) the angle of the first variable guide vane (8a) relative to the operating axis (20) increases with increasing engine speed.)

1. A controller (300) for a gas turbine engine (10), said gas turbine engine (10) comprising:

a compressor (14) having:

a housing (50) extending along an operational axis (20) and centered on said operational axis;

an array (48) of compressor blades coupled to a rotatable engine shaft (22) extending along the operational axis (20);

a first variable guide vane (8a) axially spaced from the compressor blade array (48) along the operational axis (20),

wherein the first variable guide vane (8a) is rotatably mounted at a first position (202) on the housing (50),

having a vane axis of rotation (121) at right angles to said operational axis (20); and is

The first variable guide vane (8a) is coupled to an adjustment drive (154) operable to rotate the first variable guide vane (8a) about its axis of rotation (121) to a range of angles (A-D) relative to the operational axis (20);

the controller (300) is operable to:

controlling rotation of the first variable guide vane (8a) as a function of engine shaft speed, wherein:

-the angle of the first variable guide vane (8a) with respect to the operating axis (20) in a first range (a-B) and a third range (C-D) of engine shaft speeds:

decreases as engine speed increases (R1); and/or

Increases as engine speed decreases (R2);

-the angle of the first variable guide vane (8a) with respect to the operating axis (20) in a second range (B-C) of engine shaft speeds:

increases with increasing engine speed (R2); and/or

Decreases as the engine speed decreases (R1).

2. A gas turbine engine (10), comprising:

a compressor having:

a housing (50) extending along an operational axis (20) and centered on said operational axis;

an array (48) of compressor blades coupled to a rotatable engine shaft (22) extending along the operational axis (20);

a first variable guide vane (8a) axially spaced from the compressor blade array (48) along the operational axis (20);

wherein the first variable guide vane is rotatably mounted at a first location (202) on the casing (50),

having a vane axis of rotation (121) at right angles to said operational axis (20); and is

The first variable guide vane (8a) is coupled to an adjustment drive (154) operable to rotate the first variable guide vane (8a) about its axis of rotation (121) to a range of angles (A-D) relative to the operational axis (20);

a controller (300) operable to:

controlling rotation of the first variable guide vane (8a) as a function of engine shaft speed, wherein:

-the angle of the first variable guide vane (8a) with respect to the operating axis (20) in a first range (a-B) and a third range (C-D) of engine shaft speeds:

decreases as engine speed increases (R1); and/or

Increases as engine speed decreases (R2);

-the angle of the first variable guide vane (8a) with respect to the operating axis (20) in a second range (B-C) of engine shaft speeds:

increases with increasing engine speed (R2); and/or

Decreases as the engine speed decreases (R1).

3. A method of controlling a gas turbine engine (10) according to claim 2,

the method comprises controlling the rotation of the first variable guide vane (8a) as a function of the engine shaft speed, wherein:

-the angle of the first variable guide vane (8a) with respect to the operating axis (20) in a first range (a-B) and a third range (C-D) of engine shaft speeds:

decreases as engine speed increases (R1); and/or

Increases as engine speed decreases (R2);

-the angle of the first variable guide vane (8a) with respect to the operating axis (20) in a second range (B-C) of engine shaft speeds:

increases with increasing engine speed (R2); and/or

Decreases as the engine speed decreases (R1).

4. The method of claim 3, wherein

Said second range (B-C) of engine shaft speeds is between the first range (A-B) and a third range (C-D).

5. The method of claim 4, wherein

The maximum value of the first range (A-B) is not greater than the minimum value of the second range (B-C); and

the maximum value of the second range (B-C) is not greater than the minimum value of the third range (C-D).

6. The method of any one of claims 3 to 5, wherein

A rate of change of engine shaft speed per unit change of angle of the first variable guide vane (8a) relative to the operational axis (20) is greater in the third range (C-D) than in the first range (A-B).

7. The method of any one of claims 3 to 6,

said first range (A-B) is 0 to 80% of engine shaft speed;

the second range is 80% to 90% of engine shaft speed; and

the third range is 90% to 105% of the engine shaft speed.

8. The method of any one of claims 3 to 6, wherein

The first range (A-B) is 0% to no greater than 80% of engine shaft speed;

the second range is no less than 80% to no greater than 95% of engine shaft speed; and

the third range is no less than 95% to no more than 105% of the engine shaft speed.

9. The method according to any one of claims 3 to 8, wherein the compressor further comprises:

a second variable guide vane (8b) axially spaced from the first variable guide vane (8a) along the operational axis (20),

wherein the second variable guide vane (8b) is rotatably mounted at a second position (204) on the housing (50),

having a vane axis of rotation (121b) at right angles to said operational axis (20); and

the second variable guide vane (8b) is coupled to the adjustment drive (154); the adjustment drive (154) is operable to: rotating the second variable guide vane (8b) about its axis of rotation (121) to a range of angles relative to the operational axis (20) while rotating the first variable guide vane;

the method comprises the following steps:

controlling rotation of the second variable guide vane (8b) as a function of engine shaft speed, wherein:

-the angle of the second variable guide vanes (8B) with respect to the operating axis (20) within the first (a-B), second (B-C) and third (C-D) ranges of engine shaft speeds:

decreases as engine speed increases (R1); and/or

Increases as the engine speed decreases (R2).

10. The method of claim 9, wherein rotation of a plurality of the variable guide vanes is controlled such that:

within said first range (A-B) of engine shaft speeds,

the angle of the first and second variable guide vanes (8a, 8b) relative to the operational axis (20):

at the same rate.

11. The method of claim 9 or 10, wherein rotation of a plurality of the variable guide vanes is controlled such that:

within said third range (C-D) of engine shaft speed

The angle of the first variable guide vane (8a)

Changes at a greater rate than the second variable guide vane (8 b).

12. The method of claim 11, wherein the adjustment drive (154) comprises one actuator (156), the actuator (156) being coupled to both the first variable guide vane (8a) and the second variable guide vane (8 b).

13. The method of claim 11, wherein

The adjustment drive (154) comprising a first actuator (156) and a second actuator (156'),

the first actuator (156) is coupled to the first variable guide vane (8 a); and is

The second actuator (156') is coupled to the second variable guide vane (8 b); and is

The controller (300) is operable to control two actuators (156, 156') of the plurality of actuators of the adjustment drive (154).

14. The method of any one of claims 9 to 13, wherein

Controlling rotation of the first and second variable guide vane stages (8a, 8b) is achieved by: gradually closing the first stage variable guide vanes (8a) while gradually opening the following variable guide vane stages (8b) under predetermined engine operating conditions.

15. The method of any one of claims 9 to 14, wherein

Controlling rotation of the first and second variable guide vane stages (8a, 8b) is achieved by: gradually opening the first stage variable guide vanes (8a) while gradually closing the following variable guide vane stages (8b) under predetermined engine operating conditions.

Technical Field

The present disclosure relates to control of a compressor.

In particular, the present disclosure relates to control of a compressor for a gas turbine engine.

Background

A gas turbine includes a turbine and a compressor driven by the turbine. The compressor may be comprised of multiple stages of stator vanes that may not rotate about an operational axis and rotor blades that may rotate about the operational axis. Typically, gas turbines are subjected to varying operating conditions, resulting in different aerodynamic flow conditions within the compressor.

In order to adapt the compressor performance to different flow conditions, it is known to provide the compressor with Variable Guide Vanes (VGV). The variable guide vane may be pivoted/rotated about a longitudinal axis of the variable guide vane in order to adjust the angle of the variable guide vane relative to the operating axis of the engine (i.e. the axial flow direction through the compressor) and thus the angle of the variable guide vane relative to the downstream rotor blades.

During the start-up process and under off-design conditions, operating flow conditions may result in a stall condition. This may result in aerodynamic noise, loss of efficiency and excessive rotor vibration.

To avoid such adverse behavior, the engine may be controlled to avoid a combination of conditions that may lead to stalling. For example, compressor stall may be reduced by rotating the variable guide vanes to increase the angle of the blades relative to the operational axis and reduce the compressor throat area, thereby reducing the mass flow of air through the compressor.

Unfortunately, limiting the operating state may have further consequences, such as an impact on efficiency or power output.

Therefore, there is a great need for a method of controlling a compressor and/or engine operable according to the method that reduces the likelihood of unnecessary aerodynamic behavior, thereby reducing the likelihood of damage to the engine, and at the same time allowing the engine to operate over a wider range of conditions.

Disclosure of Invention

In accordance with the present disclosure, there are provided apparatus, systems, methods, and tangible, non-transitory computer-readable storage media as set forth in the appended claims. Further features of the invention will become apparent from the dependent claims and the subsequent description.

Accordingly, a controller (300) for a gas turbine engine (10) may be provided, the gas turbine engine (10) including a compressor (14) having a casing (50) extending along and centered on an operating axis (20). The compressor may further include an array of compressor blades (48) coupled to a rotatable engine shaft (22) extending along an operational axis (20), a first variable guide vane (8a) axially spaced from the array of compressor blades (48) along the operational axis (20), wherein the first variable guide vane (8a) is rotatably mounted at a first location (202) on the casing (50) with a vane rotational axis (121) at right angles to the operational axis (20). The first variable guide vane (8a) may be coupled to an adjustment drive (154) operable to rotate the first variable guide vane (8a) about a rotational axis (121) of the first variable guide vane to an angular range (a-D) relative to the operational axis (20). The controller (300) is operable to control rotation of the first variable guide vane (8a) as a function of engine shaft speed, wherein within a first range (a-B) and a third range (C-D) of engine shaft speeds, an angle of the first variable guide vane (8a) relative to the operational axis (20) decreases (R1) with increasing engine speed and/or increases (R2) with decreasing engine speed. Within a second range (B-C) of engine shaft speeds, the angle of the first variable guide vane (8a) relative to the operating axis (20) increases (R2) with increasing engine speed and/or decreases (R1) with decreasing engine speed.

In a second range (B-C) of engine shaft speeds, the second variable guide vane (8a) is simultaneously open as the first variable guide vane (8a) closes. Similarly, as the first variable guide vane (8a) opens, the second variable guide vane (8a) closes simultaneously.

A gas turbine engine (10) may also be provided, the gas turbine engine (10) including a compressor having a casing (50) extending along and centered on an operating axis (20). The compressor may further include an array of compressor blades (48) coupled to a rotatable engine shaft (22) extending along an operational axis (20), a first variable guide vane (8a) axially spaced from the array of compressor blades (48) along the operational axis (20), wherein the first variable guide vane (8a) is rotatably mounted at a first location (202) on the casing (50) with a vane rotational axis (121) at right angles to the operational axis (20). The first variable guide vane (8a) may be coupled to an adjustment drive (154) operable to rotate the first variable guide vane (8a) about a rotational axis (121) of the first variable guide vane to an angular range (a-D) relative to the operational axis (20). The compressor and/or engine may further include a controller (300), the controller (300) being operable to control rotation of the first variable guide vane (8a) as a function of engine shaft speed, wherein within the first (a-B) and third (C-D) ranges of engine shaft speeds, an angle of the first variable guide vane (8a) relative to the operational axis (20) may decrease (R1) with increasing engine speed and/or increase (R2) with decreasing engine speed. Within a second range (B-C) of engine shaft speeds, the angle of the first variable guide vane (8a) relative to the operating axis (20) increases (R2) with increasing engine speed and/or decreases (R1) with decreasing engine speed.

A method of controlling a gas turbine engine (10) according to the present disclosure may also be provided. The method may include controlling rotation of the first variable guide vane (8a) as a function of engine shaft speed, wherein within a first range (a-B) and a third range (C-D) of engine shaft speeds, an angle of the first variable guide vane (8a) relative to the operating axis (20) decreases (R1) with increasing engine speed and/or increases (R2) with decreasing engine speed. Within a second range (B-C) of engine shaft speeds, the angle of the first variable guide vane (8a) relative to the operational axis (20) may increase (R2) with increasing engine speed; and/or decreases as engine speed decreases (R1).

The second range (B-C) of engine shaft speeds may be between the first range (A-B) and the third range (C-D).

The maximum value of the first range (A-B) may be not more than the minimum value of the second range (B-C). The maximum value of the second range (B-C) may be not more than the minimum value of the third range (C-D).

In some cases, the normalized angle of any or all of the guide vanes (8a, 8B, 8c, and 8d) may be constant, i.e., the angle is constant in the first range (a-B).

The rate of change of the engine shaft speed per unit change of angle of the operating axis (20) may be greater for the first variable guide vane (8a) in the third range (C-D) than for the first range (A-B).

The first range (A-B) may be 0% to 80% of the engine shaft speed. The second range may be 80% to 90% of the engine shaft speed. The third range may be 90% to 100% of the engine shaft speed.

The first range (A-B) may be 0% to no greater than 80% of the engine shaft speed. The second range may be no less than 80% to no more than 95% of the engine shaft speed. The third range may be no less than 95% to no more than 100% of the engine shaft speed.

The compressor may further comprise a second variable guide vane (8b), the second variable guide vane (8b) being axially spaced from the first variable guide vane (8a) along the operational axis (20), wherein the second variable guide vane (8b) is rotatably mounted at a second location (204) on the casing (50) having a vane rotational axis (121b) at right angles to the operational axis (20); and the second variable guide vane (8b) is coupled to a modulation drive (154), the modulation drive (154) being operable to: simultaneously with rotating the first variable guide vane, rotating the second variable guide vane (8b) about its axis of rotation (121) to a range of angles relative to the operational axis (20). The method may further comprise the steps of: controlling rotation of the second variable guide vane (8B) as a function of engine shaft speed, wherein within a first range (A-B), a second range (B-C) and a third range (C-D) of engine shaft speeds, the angle of the second variable guide vane (8B) with respect to the operational axis (20): decreasing with increasing engine speed (R1) and/or increasing with decreasing engine speed (R2).

The rotation of the variable guide vane may be controlled such that: the angle of the first variable guide vane (8a) and the second variable guide vane (8b) relative to the operational axis (20) over a first range (AB) of engine shaft speeds) vary at the same rate.

The rotation of the variable guide vane may be controlled such that: within a third range (C-D) of engine shaft speeds, the angle of the first variable guide vane (8a) varies at a greater rate than the second variable guide vane (8 b).

The modulation driver (154) may include an actuator (156) coupled to both the first variable guide vane (8a) and the second variable guide vane (8 b).

The modulation drive (154) may include a first actuator (156) and a second actuator (156'), the first actuator (156) being coupled to the first variable guide vane (8 a); and a second actuator (156') coupled to the second variable guide vane (8 b); and the controller (300) is operable to control two of the actuators (156, 156') of the adjustment drive (154).

A tangible, non-transitory computer readable storage medium may also be provided having instructions recorded thereon, which when executed by a controller for a gas turbine according to the present disclosure, cause the controller to perform a method of controlling a gas turbine according to the present disclosure.

Accordingly, a system for performing a variable guide vane schedule to improve compressor operability is provided. The schedule is designed to cause changes in one or more directions of at least one variable guide vane stage. The schedule is also designed such that the angle of at least one variable vane stage may be varied relative to other variable guide vane stages. This provides sufficient control of the airflow to avoid stalling.

Thus, under predetermined engine operating conditions, control may be achieved by gradually closing or opening the first stage variable guide vanes while gradually opening or closing (respectively) the following variable guide vane stages. In this way, the load on the downstream rotor blades is reduced, thereby avoiding stall conditions and other adverse blade dynamics issues.

Drawings

Examples of the present disclosure will now be described with reference to the accompanying drawings, in which:

FIG. 1 illustrates a schematic diagram of an example of a turbomachine;

FIG. 2 is a view of a compressor assembly;

FIG. 3 illustrates an enlarged region of the compressor assembly shown in FIG. 2;

FIG. 4 illustrates another enlarged region of the compressor assembly shown in FIG. 2; and is

FIG. 5 illustrates an example of a variable guide vane motion profile in accordance with methods, apparatus, and systems of the present disclosure.

Detailed Description

The present disclosure relates to a controller (300) for a gas turbine engine (10), the gas turbine engine (10) comprising a compressor. The present disclosure also relates to a gas turbine engine, a method of controlling the gas turbine engine, and a tangible, non-transitory computer-readable storage medium.

By way of context, fig. 1-4 illustrate an engine and compressor arrangement to which features of the present disclosure may be applied. However, features of the present disclosure may also be applied to other arrangements, e.g., involving different or alternative combinations of the features.

FIG. 1 illustrates an example of a gas turbine engine 10 in cross-section. The gas turbine engine 10 includes, in flow order, an inlet 12, a compressor or compressor section 14, a combustor section 16, and a turbine section 18, which are generally arranged in flow order and generally about and in the direction of an axis of rotation 20. The axis of rotation may also be referred to as the "operational axis" and the direction of flow through the compressor is generally aligned with the operational axis/axis of rotation. The gas turbine engine 10 also includes a shaft 22, the shaft 22 being rotatable about the axis of rotation 20 and extending longitudinally through the gas turbine engine 10. A shaft 22 drivingly connects the turbine section 18 to the compressor section 14.

During operation of the gas turbine engine 10, air 24 drawn in through the air inlet 12 is compressed by the compressor 14 and delivered to the combustion or combustor section 16. The combustor section 16 includes a combustor plenum 26, one or more combustion chambers 28 extending along a longitudinal axis 35, and at least one combustor 30 secured to each combustion chamber 28. The combustion chamber 28 and the burner 30 are located within the burner plenum 26. Compressed air passing through the compressor 14 enters the diffuser 32 and is discharged from the diffuser 32 into the combustor plenum 26, with a portion of the air entering the combustor 30 from the combustor plenum 26 and being mixed with gaseous or liquid fuel. The air/fuel mixture is then combusted and combustion gases 34 or working gases from the combustion are channeled to turbine section 18 through combustor 28 via transition duct 17.

The exemplary gas turbine engine 10 has a can-annular combustor section arrangement 16, the can-annular combustor section arrangement 16 being comprised of an annular array of combustor cans 19, each combustor can having a combustor 30 and a combustion chamber 28, and a transition duct 17 having a generally circular inlet that meets the combustion chamber 28 and an outlet in the form of an annular segment. The annular array of transition duct outlets forms an annular space for directing the combustion gases to the turbine 18.

The turbine section 18 includes a plurality of bucket carrier disks 36 attached to the shaft 22. In this example, two disks 36 are shown, the disks 36 each carrying an annular array of turbine buckets 38. However, the number of bucket carrying disks may be different, i.e. may be only one disk or more than two disks. Additionally, guide vanes 40 secured to a stator 42 of the gas turbine engine 10 are disposed between stages of the annular array of turbine blades 38. A guide vane 44 is disposed between the outlet of the combustor 28 and the inlet of the leading turbine blade 38, and the guide vane 44 diverts the flow of working gas onto the turbine blade 38.

Combustion gases 34 from combustor 28 enter turbine section 18 and drive turbine blades 38, which turbine blades 38 in turn rotate shaft 22. The guide vanes 40, 44 serve to optimize the angle of the combustion or working gas 34 on the turbine blades 38.

The turbine section 18 drives the compressor 14 via a shaft 22, i.e. in particular drives the compressor rotor.

The compressor 14 includes an axially series connected stationary vane stage 46, or inducer stationary vane stage 46, and a rotor moving vane stage 48. The rotor blade stage 48 includes a rotor disk for supporting an annular array of blades. The compressor 14 also includes a casing 50, the casing 50 surrounding the rotor moving blade stages 48 and supporting the guide vane stages 46. The housing 50 extends along the operational axis 20 and is centered on the operational axis 20. The guide vane stage 46 includes an annular array of radially extending guide vanes 7 mounted to a casing 50. The guide vanes 7 (also referred to below as vanes 7) are arranged to provide airflow at an optimum angle to blades of a rotor blade stage 48 at a given engine operating point, the rotor blade stage 48 being present in the vicinity of the compressor 14 and downstream of the compressor 14 along the compressor 14 with respect to the flow direction of the air 24.

The housing 50 defines a radially outer surface 52 of a passage 56 of the compressor 14. The guide vane stages 46 and the rotor moving vane stages 48 are alternately arranged in the passage 56 substantially in the axial direction. The passages 56 define a flow path for air through the compressor 14, which is also referred to as an axial flow path 56 of the compressor 14. Air 24 from the inlet 12 flows over and around the inducer static stages 46 and the rotor moving blade stages 48. The radially inner surface 54 of the channel 56 is at least partially defined by the rotor drum 53 of the rotor, the rotor drum 53 being partially defined by the annular array of buckets.

Some of the guide vane stages 46 have variable guide vanes 8 (illustrated as vanes 8a, 8b, 8c, 8d), wherein the angle of the guide vanes 8 about the longitudinal axis of the guide vanes 8 themselves may be adjusted for angle according to the flow characteristics that may occur under different engine operating conditions. Other guide vane stages 46 have fixed guide vanes 9, wherein the angle of the guide vanes 9 about the longitudinal axis of the guide vanes 9 themselves is fixed, so that the angle cannot be adjusted.

The present methods, apparatus, and systems are described with reference to the above exemplary turbine engine having a single shaft or spool connecting a single multi-stage compressor and a single one-stage or multi-stage turbine. However, it should be understood that the present system and method are equally applicable to two-shaft engines or three-shaft engines, and may be used in industrial, aeronautical, or marine applications.

Further, the can-annular combustor section arrangement 16 is also used for exemplary purposes, and it should be understood that the present technique is equally applicable to gas turbine engines 10 having both annular type and can type combustors.

Unless otherwise specified, the terms "axial," "radial," and "circumferential" are with respect to the rotational axis 20 of the engine.

In the example shown in FIG. 2, the pitch or angular offset of individual stages of variable guide vanes 8a-d inside the compressor wall 50 is controlled via a linkage mechanism 100 applied from the outside of the wall.

Each individual vane 8a (first stage 46a), 8b (second stage 46b), 8c (third stage 46c), 8d (fourth stage 46d) may be mounted on the main shaft 122 to allow angular movement of the vanes 8a, 8 b. Fig. 3 shows a single vane 8a and a corresponding lever 120 of a first stage, for example the most upstream stage of the compressor. FIG. 4 illustrates a view along the length of a vane 8a showing how the vane rotates about its axis of rotation 121.

As shown in fig. 2, lever 120 can connect main shaft 122 to drive ring 140, which drive ring 140 is provided as an adjustment ring, a so-called unison ring. Each vane 8 of each stage 46 is connected to each vane respective unison ring via levers 120. That is, lever 120 connects main shaft 122 of each vane to respective drive rings 140, 141, 142, 143.

All vanes 8 in a single stage may be connected to the same ring such that all vanes 8 on the same stage 46 are modulated simultaneously and at the same angle.

Each of drive rings 140, 141, 142, 143 can be rotated by dispenser drive 154 via push rods 150, one for each ring.

The dispenser driver may comprise only a single actuator (i.e. driver). A single driver may thus provide input to act on all of the pushrods 150, unison ring 140 and 143, and thus on the guide vanes.

Alternatively, the dispenser driver may comprise two or more actuators. Thus, one actuator may drive one or more unison rings, while another actuator drives the remaining unison ring(s). Thus, multiple drivers may provide input to act on all of the pushrods 150, unison ring 140, 143, and thus on the guide vanes.

Rotational movement of the drive ring 140, 141, 142, 143 (shown as arrows s1, s2, s3, s4) may be applied to the lever 120 of each vane 8a to 8d via the lever 120 in a rotational movement, which is indicated via arrow m 2. Therefore, as shown in fig. 3, 4, the movement of the distributor drive shaft 152 causes the rotation of the vanes 8a to 8 d.

Ignoring the details of the variable guide vane actuation arrangement, the gas turbine engine 10 according to the present disclosure includes a compressor having a casing 50 extending along the operational axis 20 and centered on the operational axis 20. An array 48 of compressor blades coupled to the rotatable engine shaft 22 extends along the operational axis 20, and the first variable guide vane 8a is axially spaced from the array 48 of compressor blades along the operational axis 20. A first variable guide vane is rotatably mounted on the casing 50 at a first location 202, the first variable guide vane having a vane rotational axis 121 extending radially from the operational axis 20 and at right angles to the operational axis 20. The first variable guide vane 8a is coupled to an adjustment drive 154, which adjustment drive 154 is operable to rotate the first variable guide vane 8a about the first variable guide vane axis of rotation 121 to an angular range a-D (i.e., angular orientation) relative to the operational axis 20.

As shown in FIG. 4, for example, the angle of the variable guide vane relative to the operational axis 20 may be considered in terms of the angle formed by a chord line 123 between the vane leading and trailing edges and the operational axis 20.

A feature common to all examples covered by the present disclosure is that the first stage 46a operates in conjunction with the subsequent stages 46b, 46c, 46 d. However, the stages 46b, 46c, 46d are synchronized with each other, but the stage 46a is configured to turn on and off according to a different schedule.

In other words, the opening/closing of the stages 46b, 46c, 46d is synchronous in that they all open and close simultaneously, while the opening/closing of the first stage 46a is asynchronous with respect to the other stages in that the first stage 46a may open at the time the other stages close and may close at a different rate than the other stages. This is best illustrated with reference to fig. 5.

FIG. 5 illustrates a graph of variable guide vane angle plotted against engine speed for vanes 8a, 8b, 8c, 8d of different stages 46a, 46b, 46c, 46 d. As seen with reference to the graphical time charts of the vanes 8b, 8c, 8d, at low engine speeds, the vanes are disposed at a first angle relative to the operational axis 20 (and/or the direction of flow through the compressor), and as engine speed increases, the vanes rotate relative to the operational axis 20 (e.g., in the direction R2 shown in fig. 4) such that the vanes are at a most "open" condition at a highest engine speed to allow for a maximum air flow.

As shown by the curve labeled 8 a' in fig. 5, in a conventional compressor for a gas turbine engine, the vanes of the first stage 46a will follow the same pattern.

However, as shown at 8a in fig. 5, for the arrangement of the present disclosure, the curve of the first level corresponds to a time schedule.

As shown in FIG. 2, the gas turbine engine includes a controller 300, such as shown in FIG. 5, the controller 300 operable to control rotation of the first variable guide vanes 8a as a function of engine shaft speed.

The controller 300 may form part of an engine control unit and may be mounted to or in any suitable location on or near the engine and/or compressor. The controller 300 is linked to the distributor driver 154 and is operable to control the distributor driver 154, thereby controlling the variable guide vanes 8a, 8b, 8c, 8 d.

Thus, regardless of how the variable guide vanes 8a, 8b, 8c, 8d are actuated/rotated, their orientation, direction of rotation, and speed of rotation are controlled by the controller 300.

Referring to fig. 5, the controller 300 is operable to control rotation of the variable guide vanes 8a such that the angle of the first variable guide vanes 8a relative to the operating axis 20 decreases with increasing engine speed (i.e., turning in the direction R1 as shown in fig. 4 to increase the flow area between the vanes 8a) and/or increases with decreasing engine speed (i.e., turning in the direction R2 as shown in fig. 4 to decrease the flow area between the vanes 8a) over the first range (a-B) and the third range (C-D) of engine shaft speeds. Referring also to fig. 5, the controller 300 may also be operable to control the rotation of the variable guide vanes 8a such that, within a second range of engine shaft speeds (B-C), the angle of the first variable guide vanes 8a relative to the operational axis 20 increases with increasing engine speed (i.e., turns in the direction R2) and/or decreases with decreasing engine speed (i.e., turns in the direction R1).

Accordingly, a controller 300 is provided, the controller 300 being operable to rotate the first variable guide vane 8a about the first variable guide vane rotational axis 121 to an angular range a-D relative to the operational axis 20 (i.e., angular orientation in directions R1, R2). Accordingly, the controller 300 is operable to control rotation of the first variable guide vane 8a as a function of engine shaft speed, wherein the angle of the first variable guide vane 8a relative to the operational axis 20 decreases (i.e., turns in the direction of direction R1) with increasing engine speed over the first and third ranges a-B and C-D of engine shaft speed; and/or increases as engine speed decreases (i.e., rotates in direction R2). Within a second range of engine shaft speeds, B-C, the angle of the first variable guide vanes 8a relative to the operational axis 20 increases (i.e., rotates in direction R2) with increasing engine speed; and/or decreases as engine speed decreases (i.e., rotates in direction R1).

As shown in fig. 4, the first rotational direction R1 is opposite the second rotational direction R2.

As described above, the variable guide vane 8a may be one of an array of variable guide vanes 8a arranged around the circumference of the casing 50 to form at least a portion of the first flow stage 46 a.

Also as described, another array/stage 46b, 46c, 46d of variable guide vanes 8b, 8c, 8d may also be provided, the variable guide vanes 8b, 8c, 8d each being arranged about a circumference of the casing 50 to form at least a portion of another flow stage 46b, 46c, 46d, the other flow stage 46b, 46c, 46d being spaced from the first flow stage 46a along the operational axis 20.

Accordingly, a second (or more) array/stage 46b, 46c, 46d of variable guide vanes 8b, 8c, 8d arranged about the circumference of the casing 50 may be provided, forming at least a portion of a second, third and/or fourth flow stage 46a, 46b, 46d, the second, third and/or fourth flow stage 46a, 46b, 46d being spaced apart from the first flow stage 46a along the operational axis 20.

Therefore, it is also possible to provide a second variable guide vane 8b, which second variable guide vane 8b is axially spaced from the first variable guide vane 8a along the operational axis 20, wherein the second variable guide vane 8b is rotatably mounted at a second position 204 on the casing 50, having a vane rotation axis 121b, which vane rotation axis 121b extends radially from the operational axis 20 and is at right angles to the operational axis 20. The second variable guide vane 8b may be coupled to an adjustment driver 154, which adjustment driver 154 is operable to rotate the second variable guide vane 8b about its rotational axis 121 to an angular range a-D (angular orientation) relative to the operational axis 20 while rotating the first variable guide vane 8 a.

When an axial compressor 14 having a plurality of stages is operated, compression of air passing through the compressor is achieved in steps and with similar compression ratios at each stage, so the area of the gas path through the compressor is designed to be gradually reduced. At very low speeds encountered during engine start-up and shut-down, the early stage variable guide vanes 8a, 8b fail to provide sufficient compression to enable flow through the trailing (downstream) vane stages 46c, 46d that become "choked". When this occurs, the flow may separate from the airfoil surfaces, causing "stall" and reverse flow in all stages of the compressor 14. When this occurs, high pressure air exiting the compressor flows back through the compressor 14, creating a pressure wave (known as "surge"). Typically, surge will occur repeatedly until the engine stops.

However, the arrangement of the present disclosure controls the airflow to avoid the occurrence of a stall condition. Fig. 5 illustrates the relative movement of a first stage 46a in one arrangement according to the present disclosure, relative to the subsequent stages 46b, 46c, 46d, which relative movement has been determined to affect air flow such that, with the first stage 46a, the occurrence of stall and/or other adverse air flow conditions will be inhibited, the first stage 46a being restricted compared to other stages under predetermined engine conditions.

At low speeds, the variable guide vanes are "closed" (i.e., rotated in direction R2 to restrict flow to a maximum extent), and as engine speed increases, the variable guide vanes 8 a-8 d open in direction R1 to the operating position of the variable guide vanes to pass more flow.

Accordingly, a control method of controlling the rotation of the first variable guide vane 8a according to the engine shaft speed is provided. Within the first and third ranges A-B, C-D of engine speeds, the angle of the first variable guide vanes 8a relative to the operating axis 20 decreases as engine speed increases (i.e., rotates in the direction R1) and/or increases as engine speed decreases (i.e., rotates in the direction R2). Within a second range B-C of engine shaft speeds, the angle of the first variable guide vanes 8a relative to the operating axis 20 increases as engine speed increases (i.e., rotates in direction R2) and/or decreases as engine speed decreases (i.e., rotates in direction R1).

The second range (B-C) of engine shaft speeds may be between the first range (A-B) and the third range (C-D).

The maximum value of the first range (A-B) may be not more than the minimum value of the second range (B-C). The maximum value of the second range (B-C) may be not more than the minimum value of the third range (C-D).

The rate of change of the engine shaft speed per unit change of angle of the operating axis 20 may be greater for the first variable guide vane 8a in the third range (C-D) than for the first range (a-B).

The control method may further include the steps of: the rotation of the second variable guide vanes 8B is controlled according to the engine shaft speed, wherein the angle of the variable guide vanes 8a with respect to the operation axis 20 decreases with increasing engine speed (i.e., rotation in the direction R1) and/or increases with decreasing engine speed (i.e., rotation in the direction R2) within the first range (a-B), the second range, and the third range (CD) of engine shaft speeds. In the step of controlling the rotation of the second variable guide vane 8b according to the engine shaft speed, the second variable guide vane 8b is driven via the first variable guide vane 8a such that the second variable guide vane 8b is in mechanical relationship with the first variable guide vane 8a or is mechanically coupled with the first variable guide vane 8 a. The first variable guide vane 8a may be an inlet guide vane.

As shown in fig. 5, the angles of the first and second variable guide vanes 8a and 8B relative to the operational axis 20 change at substantially the same rate over a first range of engine shaft speeds (a-B).

The rotation of the variable guide vane may be controlled such that: within a third range (C-D) of engine shaft speeds, the angle of the first variable guide vane 8a varies at a substantially greater rate than the second variable guide vane 8 b.

The modulation driver 154 may include one actuator 156, the actuator 156 being coupled with both the first variable guide vane 8a and the second variable guide vane 8 b.

Alternatively, the modulation drive 154 may include a first actuator 156 and a second actuator 156', the first actuator 156 being coupled to the first variable guide vane 8 a; and the second actuator 156' is coupled to the second variable guide vane 8 b; and the controller 300 is operable to control both actuators 156, 156' of the adjustment drive 154.

Additionally, the second and first flow stages are configured such that the vanes 8b of the second flow stage 46b will move a different amount and/or in a different direction than the variable vanes of the first flow stage 46a at a predetermined flow condition of the compressor 14. The predetermined flow condition may be expressed in terms of engine speed. That is, referring to FIG. 5, the control method may define point "B" as a first percentage of the maximum engine speed and point "C" as a second percentage of the maximum engine speed.

Point "B" may be in the range of 70% to 80% of maximum engine speed, while point C is in the range of 85% to 95% of maximum engine speed.

Point "B" may be 80% of the maximum engine speed, while point C may be 90% of the maximum engine speed.

Alternatively, point "B" may be at 80% of maximum engine speed, while point C may be at 95% of maximum engine speed.

In one example, the first engine shaft speed range (A-B) may be 0 to 80% of the engine shaft speed. The second engine shaft speed range (B-C) may be 80% to 90% of the engine shaft speed. The third engine shaft speed range (C-D) may be 90% to 100% of the engine shaft speed, or even 90% to 105% of the engine shaft speed.

In an alternative example, the first range (A-B) may be 0% to no greater than 80% of the engine shaft speed. The second range (B-C) may be no less than 80% to no more than 95% of the engine shaft speed. The third range (C-D) is no less than 95% to no more than 105% of the engine shaft speed.

A non-transitory computer readable storage medium may also be provided having instructions recorded thereon that, when executed by the controller 300 for the gas turbine 10, cause the controller 300 to perform a method of controlling the gas turbine 10 in accordance with the methods of the present disclosure.

Accordingly, a mechanism is provided for operating variable guide vanes of a compressor on a schedule to improve operability of the compressor. The system includes a controller, an engine, and/or a method that advantageously closes the first stage variable inlet guide vanes while turning on other compressor stages of the compressor. Stall is typically avoided by turning on all stages of the compressor, but for inefficient compressor flow conditions, the system of the present disclosure provides further anti-stall capability.

Thus, the system of the present disclosure provides for an extension of the stall/surge margin, as well as avoiding/reducing the strength of stall when it occurs, and also reducing the "forcing" of downstream rotor blades to reduce adverse blade dynamics issues.

Thus, an arrangement is provided which enables a "programmed" schedule of operation (i.e. a predetermined motion profile) of the variable guide vane stage, thereby avoiding stall and other potentially damaging airflow conditions. It also enables multiple variable guide vane stages to operate according to different predetermined on/off schedules to avoid stall and other potentially damaging airflow conditions.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.