Pressurized gas flow to rotate the compressor during engine shutdown

Abstract

A gas turbine engine includes a compressor section having a compressor rotor shaft assembly including a plurality of compressor rotors longitudinally spaced apart from one another via respective ones of a plurality of shaft sections of a rotor shaft, each of the plurality of compressor rotors having a plurality of rotor vanes extending radially outward from the compressor rotor and circumferentially spaced apart about the compressor rotor. A stator shroud assembly has a stator shroud housing surrounding the compressor rotor shaft assembly, a compressor flow passage being defined between the compressor rotor shaft assembly and the stator shroud housing. A pressurized air source generates a pressurized air flow for providing to the compressor section, and a plurality of pressurized air flow nozzles are connected with the pressurized air source and provide the pressurized air flow into the compressor flow passage to rotate the compressor rotor shaft assembly.

Description

Technical Field

[0001] This disclosure relates to rotating a pressurized airflow in a compressor during engine shutdown. More specifically, this disclosure provides a system that injects a pressurized airflow into the compressor section of a gas turbine engine to rotate and cool the compressor rotor during engine shutdown, thereby mitigating rotor bending conditions. Background Technology

[0002] Typically, when a turbocharged engine shuts down, heat stratifies within the engine core due to the high temperatures inside. In compressors, more specifically in high-pressure compressors, the top of the compressor rotor tends to become hotter than the bottom due to the rising heat within the compressor section. This results in asymmetrical thermal expansion between the top and bottom of the compressor rotor. This can lead to a bent rotor condition, where the upper part of the rotor may contact the lower part of the surrounding engine housing as it rotates, and the lower part of the housing does not expand radially as much as the upper part. During subsequent engine starts in this bent rotor condition, repeated contact or friction between the compressor rotor and the engine housing during rotation can potentially damage the engine. Attached Figure Description

[0003] The features and advantages of this disclosure will be apparent from the following description of various exemplary embodiments, as shown in the accompanying drawings, wherein similar reference numerals generally denote the same, functionally similar and / or structurally similar elements.

[0004] Figure 1 This is a schematic partial cross-sectional side view of an exemplary high-bypass turbofan jet engine according to aspects of this disclosure.

[0005] Figure 2 Based on aspects of this disclosure Figure 1 A detailed view of the front section of the core engine, taken at point 100.

[0006] Figure 3 Based on aspects of this disclosure Figure 1 A schematic rear view of the compressor rotor taken from plane 3-3.

[0007] Figure 4 Based on aspects of this disclosure Figure 2 A magnified view of a portion of the compressor section taken at point 125 in the detailed view.

[0008] Figure 5 This is a schematic side view depicting an example of a pressurized airflow from a pressurized airflow nozzle according to aspects of this disclosure.

[0009] Figure 6This is a schematic side view depicting an example of a pressurized airflow from a pressurized airflow nozzle according to another aspect of this disclosure.

[0010] Figure 7 Based on aspects of this disclosure Figure 6 A partial cross-sectional rear view taken at point 7-7 on the plane.

[0011] Figure 8 This is a schematic diagram depicting an example of a stator blade including a stator blade airflow passage according to aspects of this disclosure.

[0012] Figure 9 Based on aspects of this disclosure Figure 8 A schematic diagram of the variable stator blades and compressor rotor blades taken from plane 9-9, with the stator housing removed.

[0013] Figure 10 Based on the present aspects of this disclosure Figure 2 A schematic partial cross-sectional view of the rotor section of the compressor rotor shaft assembly, taken at plane 10-10.

[0014] Figure 11 This is a flowchart of the processing steps of a method for operating a gas turbine engine according to aspects of this disclosure. Detailed Implementation

[0015] The features, advantages, and embodiments of this disclosure will be set forth or apparent from consideration of the following detailed description, drawings, and claims. Furthermore, it should be understood that the following detailed description is exemplary and intended to provide further explanation, and does not limit the scope of the claimed disclosure.

[0016] Various embodiments are discussed in detail below. Although specific embodiments are discussed, this is for illustrative purposes only. Those skilled in the art will recognize that other components and constructions can be used without departing from the spirit and scope of this disclosure.

[0017] As used herein, the terms “first,” “second,” and “third” are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of the individual components.

[0018] The terms "upstream" and "downstream" refer to the relative directions of fluid flow within a fluid path. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction from which the fluid flows.

[0019] Typically, when a turbocharged engine shuts down, heat stratifies within the engine core due to the high temperatures inside. In compressors, more specifically in high-pressure compressors, the top of the compressor rotor tends to become hotter than the bottom due to the increased heat within the compressor section. This stratification can result in a temperature difference of up to 500°C between the top and bottom of the compressor rotor, leading to asymmetric thermal expansion between them. In this case, the top of the compressor rotor expands radially more than the bottom, resulting in what is known as a bent rotor condition. A bent rotor condition can occur within ten minutes of engine shutdown and can persist for up to eight hours. The thermal expansion can be so great that when the upper part of the rotor rotates towards the lower part of the surrounding engine housing, the upper part of the rotor may come into contact with the lower part of the housing, which does not expand radially as much as the upper part of the engine housing. When the engine is subsequently started in a bent rotor condition, the repeated contact or friction between the compressor rotor and the engine housing during rotation can potentially damage the engine.

[0020] This disclosure addresses the aforementioned problems by providing an air-assisted bent rotor mitigation system that injects a pressurized airflow into the compressor section during engine shutdown to mitigate bent rotor conditions. More specifically, during the engine shutdown phase, a pressurized air source, either inside or outside the engine, provides a pressurized airflow through a duct system connected to multiple pressurized airflow nozzles. These nozzles may extend through the compressor stator shroud or be integrated into the stator blades, directing the pressurized airflow onto the rotor blades of the compressor rotor shaft assembly, thereby rotating the compressor rotor shaft assembly. Alternatively, a reverse exhaust flow of pressurized air may be provided to a cavity within the compressor rotor shaft to pressurize the cavity. The compressor rotor shaft includes multiple pressurized airflow nozzles therethrough, which provide a tangential pressurized airflow into the compressor flow passages, thereby generating torque and rotating the compressor rotor shaft assembly. The rotation of the compressor rotor shaft assembly during the shutdown phase provides more uniform cooling of the compressor rotor, thereby reducing the likelihood of bent rotor conditions.

[0021] Now refer to the attached diagram, Figure 1 This is a schematic partial cross-sectional side view of an exemplary high-bypass turbofan jet engine 10 (referred to herein as "engine 10") that can be incorporated into various embodiments of the present disclosure. Although further described below with reference to turbofan engines, this disclosure is also applicable to general turbomachinery, including turbojet engines, turboprop engines, and turboshaft gas turbine engines, including marine and industrial turbine engines and auxiliary power units. Figure 1As shown, engine 10 has a longitudinal centerline axis 12 extending through it from an upstream end 98 to a downstream end 99 of engine 10, for reference. Typically, engine 10 may include a fan assembly 14 and a core engine 16 disposed downstream of the fan assembly 14.

[0022] The core engine 16 typically includes a core engine housing 18 defining an annular inlet 20. The core engine housing 18 surrounds, in a series flow relationship: a compressor section (22 / 24) having a turbocharger or low-pressure (LP) compressor 22 and a high-pressure (HP) compressor 24; a combustor 26; a turbine section (28 / 30) including a high-pressure (HP) turbine 28 and a low-pressure (LP) turbine 30; and an injection exhaust nozzle section 32. A high-pressure (HP) rotor shaft 34 drivesly connects the HP turbine 28 to the HP compressor 24. A low-pressure (LP) rotor shaft 36 drivesly connects the LP turbine 30 to the LP compressor 22. The LP rotor shaft 36 may also be connected to the fan shaft 38 of the fan assembly 14. In certain embodiments, such as Figure 1 As shown, the LP rotor shaft 36 can be connected to the fan shaft 38 via a reduction gear 40, for example, in an indirect drive configuration or a gear drive configuration. In other embodiments, although not shown, the engine 10 may also include an intermediate pressure (IP) compressor and a turbine that can rotate with the intermediate pressure shaft.

[0023] like Figure 1 As shown, the fan assembly 14 includes a plurality of fan blades 42 coupled to and extending radially outward from the fan shaft 38. An annular fan housing or nacelle 44 circumferentially surrounds at least a portion of the fan assembly 14 and / or the core engine 16. In one embodiment, the nacelle 44 may be supported relative to the core engine 16 by a plurality of circumferentially spaced outlet guide vanes or struts 46. Furthermore, at least a portion of the nacelle 44 may extend over the outer portion of the core engine 16 to define a bypass airflow passage 48 therebetween.

[0024] In operation, air 56 enters the nacelle 44 at nacelle inlet 58, and a portion of this air 56 enters the compressor section (22 / 24) as compressor inlet airflow 50, where it is compressed to produce compressed air 52. Another portion of the air 56 enters bypass airflow passage 48, thus providing bypass airflow 60. The compressed air 52 from the compressor section (22 / 24) enters the combustor 26, where it mixes with fuel and is then ignited and burned to produce combustion gases 54. The combustion gases 54 pass through the HP turbine 28 and then through the LP turbine 30, thereby driving the HP compressor 24 and the LP compressor 22. Finally, the combustion gases 54 pass through the injection exhaust nozzle section 32 to provide thrust.

[0025] The operation of engine 10 can be controlled, in whole or in part, by an electronic engine controller (schematically shown at 62). An example of such controller 62 is a full authority digital engine control (“FADEC”). Controller 62 can be installed in any convenient location or within engine 10, including but not limited to within the fan nacelle or the core engine 16.

[0026] Figure 2 Based on aspects of this disclosure Figure 1 A detailed view, taken at point 100, showing a partial cross-sectional side view of the front of the core engine 16. Figure 2 In the gas turbine engine 10, there is a compressor section 64, which can correspond to Figure 1 The high-pressure (HP) compressor 24. Compressor section 64 includes a compressor rotor shaft assembly 66, which can be coupled with a high-pressure (HP) rotor shaft 34 and multiple compressor rotors 68. Figure 2 In the middle, only three compressor rotors 68 are marked, but from Figure 2 As can be readily seen, up to ten compressor rotors can be arranged in the compressor rotor shaft assembly 66. The compressor rotors 68 are longitudinally spaced apart from each other in the longitudinal direction (L) via respective rotor shaft sections 72. The rotor shaft sections 72 arranged between the respective compressor rotors 68 can be joined to the respective compressor rotors 68 by, for example, bolts. Each of the plurality of compressor rotors 68 has a plurality of compressor rotor blades 70 extending radially outward in the radial direction (R). Brief Reference Figure 3 , Figure 3 Is Figure 1 The schematic rear view of the compressor rotor 68 taken at plane 3-3 shows that multiple compressor rotor blades 70 are spaced apart around the compressor rotor 68.

[0027] Refer again Figure 2 It can also be seen that compressor section 64 includes a stator shroud assembly 74, which includes a stator housing 76 that extends circumferentially about a longitudinal centerline axis 12 and surrounds the compressor rotor shaft assembly 66. A compressor flow passage 78 is defined between the compressor rotor shaft assembly 66 and the stator housing 76. Figure 2In the exemplary compressor section 64, an axial compressor is depicted, wherein the compressor inlet airflow 50 generally flows through the compressor section 64 in a longitudinal (axial) direction (L) relative to the longitudinal centerline axis 12. The stator shroud assembly 74 also includes a plurality of stator blades 80 extending radially inward from the stator shroud housing 76. As will be described in more detail below, the plurality of stator blades 80 are circumferentially spaced from each other around the stator shroud housing 76 and disposed between respective compressor rotors in a plurality of compressor rotors 68.

[0028] When the core engine casing 18 (see also) Figure 1 When associated with compressor section 64, core engine housing 18 is arranged radially outward of stator housing 76, defining a bottom space 82 between core engine housing 18 and stator housing 76. Provided within bottom space 82 is an air-assisted bending rotor mitigation system 84. Air-assisted bending rotor mitigation system 84 can be combined with compressor bleed air system 86, which is well known in the art. More specifically, compressor bleed air system 86 is generally known to include a compressor discharge port 88 connected to a compressor bleed air duct 90 having a discharge valve 92 within the compressor bleed air duct 90. Compressor bleed air system 86 provides bleed airflow 91 from high-pressure compressor 24 for, for example, aircraft environmental control systems. Alternatively, air-assisted bending rotor mitigation system 84 can be a reverse discharge system, as described below, which provides airflow into compressor section 64 to rotate compressor rotor shaft assembly 66, thereby mitigating bending rotor conditions of the plurality of compressor rotors 68.

[0029] The air-assisted bending rotor mitigation system 84 includes a pressurized air source 94, which may be an air pump having an impeller 96 and a motor 97 driving the impeller 96. The pressurized air source 94 may be connected to a controller 62 to turn the motor 97 on and off, and / or control the speed of the motor 97. The air-assisted bending rotor mitigation system 84 includes an air duct system 103 having an intake duct 101 connected to an inlet 102 and to the pressurized air source 94 via a core engine housing 18. The pressurized air duct 104 is connected to the outlet side 106 of the pressurized air source. The pressurized air duct 104 includes a valve 108 to control the pressurized air flow 110 generated by the pressurized air source 94 to the pressurized air duct 104. The valve 108 may be connected to and controlled by the controller 62. Downstream of the valve 108 connected in the pressurized air duct 104 is a valve 112. Valve 112 can be controlled by controller 62 and allows pressurized air flow 110 to enter compressor bleed air duct 90 through it. Valve 112 can also prevent compressor bleed air 91 from flowing back into pressurized air duct 104.

[0030] A branch of the pressurized air conduit 104 is the air-assisted nozzle conduit 114. The inlet 116 of the air-assisted nozzle conduit 114 can be connected to the pressurized air conduit 104 downstream of valve 108 and upstream of valve 112, such that when valve 108 is open and pressurized air source 94 is operable to generate pressurized air 110, and valve 112 is closed, pressurized air 110 flows into the air-assisted nozzle conduit 114. Valves 118 and 120 can be seen being included within the air-assisted nozzle conduit 114.

[0031] Figure 4 Is Figure 2 A magnified view of a portion of the compressor section 64, taken at point 125 in the detailed view. (See attached image.) Figure 4 As shown, manifold 122 branches off from air-assisted nozzle line 114 downstream of valve 118, and manifold 124 branches off from air-assisted nozzle line 114 downstream of valve 120. Return to Figure 3 It can be seen that the manifold 124 extends circumferentially around the stator housing 76 and is connected to a plurality of pressurized airflow nozzles 128, which can be arranged in a first array 129 spaced apart circumferentially around the stator housing 76. Figure 3 In the diagram, the first array 129 is shown to include six pressurized airflow nozzles 128, but may include any number of pressurized airflow nozzles 128. Similarly, a manifold 122 can be seen extending circumferentially around the stator housing 76 and connected to a plurality of pressurized airflow nozzles 126, which may be arranged in a second array 131 circumferentially spaced around the stator housing 76. The plurality of pressurized airflow nozzles 126 may be circumferentially staggered relative to the plurality of pressurized airflow nozzles 128, shown for reference as pressurized airflow nozzles 126(a). Figure 4 As shown, valves 118 and 120 can be connected to controller 62 via communication signal line 130. During operation of the air-assisted bending rotor mitigation system 84, controller 62 can monitor any of several conditions of compressor section 64, such as temperature, rotational speed of compressor rotor shaft assembly 66, vibration level within the compressor, etc. Controller 62 can actuate valve 118 from a closed state to an open state to allow air from pressurized air source 94 (… Figure 2 The pressurized airflow 110 flows downstream of valve 118 to manifold 122, and optionally, valve 120 can also be actuated from a closed state to an open state to allow pressurized airflow 110 to flow to manifold 124. Manifold 122 is connected to a plurality of pressurized airflow nozzles 126 and manifold 124 is connected to a plurality of pressurized airflow nozzles 128. Figure 4As shown, pressurized airflow nozzles 126 and 128 can extend through stator housing 76 to provide pressurized airflow 110 into compressor flow passage 78, thereby rotating compressor rotor shaft assembly 66 to alleviate bending rotor conditions of compressor rotor 68 during engine shutdown phases of engine 10.

[0032] Figure 5 This is a schematic side view depicting an example of a pressurized airflow from a pressurized airflow nozzle according to aspects of this disclosure. Figure 5 As shown, for reference purposes, the plurality of compressor rotors 68 may include: a first compressor rotor 68(a) having a plurality of compressor rotor blades 70(a) circumferentially spaced around the first compressor rotor 68(a), similar to Figure 3 The compressor rotor 68 and compressor rotor blades 70 are shown in the figure; the second compressor rotor 68(b) has a plurality of compressor rotor blades 70(b) circumferentially spaced around the second compressor rotor 68(b), similar to Figure 3 The compressor rotor 68 and compressor rotor blades 70 are shown in the figure; and the third compressor rotor 68(c) has a plurality of compressor rotor blades 70(c) circumferentially spaced around the third compressor rotor 68(c), similar to Figure 3 The compressor rotor 68 and compressor rotor blades 70 are shown in the diagram above. Figure 3 The plurality of pressurized airflow nozzles 128, which can be arranged in an array circumferentially spaced around the stator housing 76, are shown as the leading edge 136 of the compressor rotor blades 70(a) of the first compressor rotor 68(a). Similarly, the pressurized airflow nozzles 126, which can be arranged in an array circumferentially around the stator housing 76 as described above, are shown as the leading edge 138 of the compressor rotor blades 70(b) of the second compressor rotor 68(b). Alternatively, the pressurized airflow nozzles 126 can be arranged through the housing 76 at a longitudinal distance 140 from the pressurized airflow nozzles 128.

[0033] Each pressurized airflow nozzle 128 is arranged at an angle 132 relative to the radial direction (R) to guide a pressurized airflow 110 from it onto a plurality of compressor rotor blades 70(a). Similarly, each pressurized airflow nozzle 126 is arranged at an angle 134 relative to the radial direction (R) to guide a pressurized airflow 110 onto a plurality of compressor rotor blades 70(b). Additionally, refer to the reference. Figure 3Multiple pressurized airflow nozzles 128 may be arranged to guide pressurized airflow 110 at an angle 142 relative to the circumferential direction (C) and radial direction (R). Thus, in this aspect, the pressurized air 110 guided onto multiple compressor rotor blades 70(a), and optionally onto compressor rotor blades 70(b), causes the compressor rotor shaft assembly 66 to rotate, thereby providing more uniform cooling of the compressor rotor blades 70(a), 70(b) during engine shutdown phases to mitigate rotor bending conditions.

[0034] Figure 6 This is a schematic side view depicting an example of a pressurized airflow from a pressurized airflow nozzle according to another aspect of this disclosure. In the foregoing aspect, a plurality of pressurized airflow nozzles 128 and a plurality of pressurized airflow nozzles 126 are configured to provide pressurized air 110 (see [reference]) through the stator shroud housing 76 against the compressor rotor blades 70. Figure 5 However, in this aspect, pressurized air 110 is instead provided by pressurized stator blades 81, which include stator blade airflow passages 144 and a plurality of pressurized airflow nozzles 146. Figure 8 An example of a pressurized stator blade 81 is depicted, comprising a stator blade airflow passage 144 therein, and a plurality of pressurized airflow nozzles 146 in fluid communication with the stator blade airflow passage 144. The plurality of pressurized airflow nozzles 146 may be arranged to pass through the trailing edge 152 of the pressurized stator blade 81, and a plurality of pressurized airflow nozzles 150 may be arranged to pass through the trailing edge 154 of the pressurized stator blade 83. When valves 118 and 120 are actuated to the open state by controller 62, and pressurized air 110 is supplied to manifold 124, pressurized air 110 flows into the stator blade airflow passage 144 and is then guided through the plurality of pressurized airflow nozzles 146 to the plurality of compressor rotor blades 70(b) of the second compressor rotor 68(b), as shown. Figure 6 As shown, this causes the compressor rotor shaft assembly 66 to rotate.

[0035] In relation to Figure 2 In the above description, a plurality of stator blades 80 extend radially inward from and are fixed to the stator housing 76. (Brief Reference) Figure 7 , Figure 7 Is Figure 6 The view taken at plane 7-7 shows multiple stator blades 80 extending circumferentially around the stator housing 76. The stator blades 80 arranged circumferentially in the same circumferential row can also be considered as a circumferential array of stator blades. Figure 5 and Figure 6 The stator blades 80(a) shown may include a plurality of stator blades 80(a) arranged in a first circumferential array 85 around the stator housing 76, similar to Figure 7 The stator blade 80 is shown. Similarly, Figure 5 and Figure 6 The stator blades 80(b) shown may include a plurality of stator blades 80(b) arranged in a second circumferential array 87 around the stator shroud housing 76, similar to Figure 7 The stator blades 80. A first circumferential array 85 of stator blades 80(a) and a second circumferential array 87 of stator blades 80(b) are spaced apart in the longitudinal direction (L) to accommodate a second compressor rotor 68(b) having compressor rotor blades 70(b) between them. In the first circumferential array 85 of stator blades 80(a), a plurality of pressurized stator blades 81 may be included in the array in place of stator blades 80(a). For example, as Figure 7 As shown, some stator blades 80(a) may be included in the first circumferential array 85, and pressurized stator blades 81 are also included in stator blades 80(a). Although Figure 7 Eight main stator blades are depicted arranged around the stator housing 76, and four pressurized stator blades 81 are depicted among the eight main stator blades. However, the number of stator blades in any circumferential array can typically include up to one hundred stator blades around the stator housing 76. In this case, the number of pressurized stator blades 81 that can be included in the circumferential array depends only on the total amount of pressurized air 110 to be ejected by the pressurized stator blades 81 to provide full rotation of the compressor rotor shaft assembly 66.

[0036] and Figure 5 In comparison, in Figure 6 In this aspect, stator blade 80(b) may alternatively include a plurality of pressurized stator blades 83. The pressurized stator blades 83 are similar to the pressurized stator blades 81 and include a stator blade airflow passage 148 therein, and a plurality of pressurized airflow nozzles 150 that inject pressurized air 110 onto the compressor rotor blades 70(c) of the third compressor rotor 68(c). The pressurized stator blades 83 may be arranged in the second circumferential array 87 in the same manner as the pressurized stator blades 81 are arranged in the first circumferential array 85. When valve 118 is actuated to the open state by controller 62 and pressurized air 110 is supplied to manifold 122, pressurized air 110 flows into the stator blade airflow passage 148 and is then guided through the plurality of pressurized airflow nozzles 150 onto the plurality of compressor rotor blades 70(c) of the third compressor rotor 68(c), such as... Figure 6 As shown, this causes the compressor rotor shaft assembly 66 to rotate.

[0037] As Figure 8A further aspect of the pressurized stator blades 81 and 83 shown herein is that the pressurized stator blades 81 and / or 83, fixed to the stator housing 76, may each alternatively be variable stator blades, which can be rotated to change the angle of the stator blades, thereby changing the angle of the pressurized airflow 110 onto the plurality of compressor rotor blades 70. For example, as Figure 8 As shown, the variable stator blades 160 and / or 162 include a stator blade shaft 156 extending through the stator shroud housing 76 and engaging with a stator blade actuator 158. A stator blade airflow passage 144 (146) extends through the stator blade shaft 156 and engages with a manifold 124 (122). The stator blade actuator 158 can be controlled by a controller 62 to rotate the variable stator blades 160 (162) about the central axis 164 of the stator blade shaft 156. For example, as... Figure 9 As shown, Figure 9 Is Figure 8 A schematic diagram of the variable stator blades and compressor rotor blades, taken at plane 9-9, where the stator housing 76 is removed, allows the stator blade actuator 158 to rotate the variable stator blade 160 (162) clockwise by an angle 166 from a first position (shown by solid lines) to a second position (shown by dashed lines). Thus, as an example, the first impact angle 168 of the pressurized airflow 110 on the compressor rotor blades 70 can change from a first impact angle 168 (shown as a right angle in the first position) to a second impact angle 170 (shown as an acute angle (less than ninety degrees)). By utilizing the variable stator blades 160 (162) to change the impact angle of the pressurized air 110 on the multiple compressor rotor blades 70, the rotational speed of the compressor rotor shaft assembly 66 can be controlled.

[0038] In the foregoing aspect, pressurized air 110 is supplied to the compressor flow passage 78 to rotate the compressor rotor shaft assembly 66 via a plurality of pressurized airflow nozzles 128 (126) extending through the stator housing 76, or via pressurized airflow 110 supplied through pressurized stator blades 80(a), 80(b), 81 or 83. In another aspect according to this disclosure, pressurized air 110 is supplied from nozzles in the compressor rotor shaft assembly 66 to the compressor flow passage 78, thereby rotating the compressor rotor shaft assembly 66. Return to Reference Figure 2In this aspect, the compressor rotor shaft assembly 66 includes a cavity 174 therein. Valve 176 is disposed in the compressor bleed air system 86 near the compressor discharge port 88, and conduit 172 connects valve 176 to cavity 174 within the compressor rotor shaft assembly 66. By this aspect, air-assisted nozzle conduit 114, valves 118 and 120, a plurality of pressurized airflow nozzles 128 and 126 may not be included as part of the air-assisted bent rotor mitigation system 84. During shutdown, the compressor discharge port 88 may be closed and the discharge valve 92 may also be closed. When the air-assisted bent rotor mitigation system 84 is activated by the controller 62, pressurized air source 94 is actuated to begin supplying pressurized airflow 110, and valves 108, 112, and 176 may be opened by the controller 62. The pressurized airflow 110 flows through the compressor bleed air duct 90 as a reverse flow (compared to the bleed airflow 91) through the pressurized air duct 104, through the open valve 176, through the duct 172, and into the cavity 174 within the compressor rotor shaft assembly 66. As a result, the cavity 174 is pressurized by the pressurized air 110.

[0039] Figure 10 Based on the present aspects of this disclosure Figure 2 A schematic partial cross-sectional view of the rotor shaft section 72 of the compressor rotor shaft assembly 66, taken at plane 10-10. (See also...) Figure 10 As seen in the diagram, the rotor shaft section 72 of the compressor rotor shaft assembly 66 includes a plurality of rotor shaft pressurized airflow nozzles 184 extending through the rotor shaft section 72. Each rotor shaft pressurized airflow nozzle 184 is arranged at a tangential angle 180 such that a pressurized airflow 110 enters the compressor flow passage 78 from the pressurization chamber 174 in a generally tangential direction relative to the outer surface 182 of the rotor shaft section 72. The pressurized air 110 through the plurality of rotor shaft pressurized airflow nozzles 184 generates a torque force, thereby causing the compressor rotor shaft assembly 66 to rotate in a rotational direction 178 opposite to the tangential pressurized airflow 110. Since the rotor shaft section 72 has a generally radially arranged array of a plurality of stator blades 80, the tangential pressurized airflow 110 from the rotor shaft pressurized airflow nozzles 184 can impinge on the stator blades 80 to provide an additional torque-generating force for rotating the compressor rotor shaft assembly 66.

[0040] In the foregoing description, pressurized air source 94 is described as constituting an air pump within the air-assisted bending rotor mitigation system 84 incorporated within the core engine 16. However, this disclosure is not limited to the air pump within the core engine 16, and alternatively, the pressurized air source may be external to the engine 10. For example, the air-assisted bending rotor mitigation system 84 may omit the air pump (pressurized air source 94) within the core engine 16, and alternatively, a ground power unit or other pressurized air source (not shown) external to the engine 10 or on an aircraft on which the engine 10 is mounted may be connected to inlet 102 to provide pressurized airflow 110 through intake duct 101. The remainder of the air-assisted bending rotor mitigation system 84, excluding pressurized air source 94 (air pump), may be implemented in the same manner as described above, thereby using pressurized air 110 to rotate the compressor rotor shaft assembly 66 to mitigate bending rotor conditions during engine shutdown phases of the engine 10.

[0041] Figure 11 This is a flowchart of the processing steps for a method to mitigate bending rotor conditions. This method can be implemented in a gas turbine engine 10, which includes the steps described above. Figures 1 to 10The air-assisted bending rotor mitigation system 84 described in any of the foregoing aspects. This method can be controlled by controller 62 as part of a shutdown phase of operation of the gas turbine engine 10. In step 1101, controller 62 initiates engine shutdown phase control. The engine shutdown phase is typically performed at the end of flight, after the aircraft has been parked, and the fuel flow to the engine's combustor is terminated to shut down the engine. Of course, the shutdown operation can be performed at any time after the engine has been operated (e.g., during a ground test run, or while taxiing between ground locations), not just at the end of flight. Similarly, for land-based or sea-based engine applications, the shutdown phase can be initiated at any time after the engine has been operational. In the method of this disclosure, when the shutdown phase is initiated, in step 1102, the controller checks (monitors) at least one condition of the compressor section 64 of the gas turbine engine 10. At least one condition can be, for example, the temperature of the compressor section 64. Alternatively, controller 62 can simply check to confirm that the fuel flow has been terminated and / or the combustor has shut down, and then automatically initiate the shutdown phase control. In step 1103, based on the result of checking at least one condition, controller 62 actuates pressurized air source 94 and actuates any one or more of valves 108, 112, 118, 120, and / or 176 to a closed or open state to begin providing pressurized airflow 110 from pressurized air source 94 to a plurality of pressurized airflow nozzles 128, 126, 146, 150, 184. In step 1104, the plurality of pressurized airflow nozzles 128, 126, 146, 150, 184 directs pressurized airflow 110 into compressor flow passage 78, and in step 1105, directing pressurized airflow 110 into compressor flow passage 78 causes compressor rotor shaft assembly 66 to rotate. In step 1106, while compressor rotor shaft assembly 66 rotates, controller 62 monitors at least one condition of compressor section 64. For example, controller 62 may monitor the temperature of compressor section 64. In step 1107, the controller determines whether a threshold for at least one condition is met during monitoring. If the controller determines that the monitored condition is above the threshold (yes in step 1107), the shutdown phase control continues to allow the compressor rotor shaft assembly 66 to continue rotating, and the controller 62 continues to monitor at least one condition. Once it is determined that the monitored condition is below the threshold (no in step 1107), the controller 62 terminates the shutdown phase control in step 1108.

[0042] Regarding the foregoing aspects, this disclosure provides an air-assisted bent rotor mitigation system and related methods to provide a pressurized airflow to the compressor section during engine shutdown, thereby causing rotation of the compressor rotor shaft assembly. By providing continuous rotation of the compressor rotor shaft assembly after engine shutdown, bent rotor conditions can be mitigated because one side (top side) of the compressor rotor shaft is not subjected to thermal stratification within the engine core. The pressurized airflow itself can also provide additional cooling to the compressor rotor blades, thereby further mitigating bent rotor conditions.

[0043] While the foregoing description generally pertains to gas turbine engines, gas turbine engines can be implemented in a variety of environments. For example, the engine can be implemented in aircraft, but it can also be implemented in non-aircraft applications (such as power plants, marine applications, or oil and gas production applications). Therefore, this disclosure is not limited to use in aircraft.

[0044] Further aspects of this disclosure are provided by the subject matter of the following clauses.

[0045] A gas turbine engine includes: a compressor section comprising: (a) a compressor rotor shaft assembly including a plurality of compressor rotors longitudinally spaced apart from each other via respective shaft segments of a plurality of shaft segments of a rotor shaft, each compressor rotor having a plurality of rotor blades extending radially outward from the compressor rotor and circumferentially spaced around the compressor rotor; and (b) a stator shroud assembly including a stator shroud housing surrounding the compressor rotor shaft assembly, a compressor flow passage defined between the compressor rotor shaft assembly and the stator shroud housing; a pressurized air source generating a pressurized airflow to be supplied to the compressor section; and a plurality of pressurized airflow nozzles connected to the pressurized air source and supplying the pressurized airflow into the compressor flow passage to rotate the compressor rotor shaft assembly.

[0046] The gas turbine engine according to the foregoing clause, wherein the gas turbine engine is installed in the aircraft, and the pressurized air source is any one of the auxiliary power unit installed in the aircraft, the air pump installed in the aircraft, and an air source outside the aircraft and connected to the aircraft during the shutdown phase of the gas turbine engine.

[0047] According to any of the preceding clauses, in a gas turbine engine, wherein the compressor rotor shaft assembly defines a pressurized chamber in fluid communication with the pressurized air source, and the plurality of pressurized airflow nozzles are arranged through at least one rotor shaft section of the compressor rotor shaft assembly, the plurality of pressurized airflow nozzles being circumferentially spaced and arranged to provide tangential airflow therefrom to the compressor flow passage relative to the circumferential direction about the compressor rotor shaft assembly, so as to rotate the compressor rotor shaft assembly.

[0048] According to any of the preceding clauses of the gas turbine engine, wherein the stator shroud assembly includes a plurality of pressurized stator blades, each of the pressurized stator blades including: (i) a stator blade airflow passage within the pressurized stator blade, the stator blade airflow passage being in fluid communication with the pressurized air source; and (ii) at least one of the plurality of pressurized airflow nozzles, the at least one pressurized airflow nozzle being arranged to direct the pressurized airflow onto the plurality of rotor blades of at least one of the plurality of compressor rotors to rotate the compressor rotor shaft assembly.

[0049] According to any of the preceding clauses, in the gas turbine engine, each of the plurality of pressurized stator blades is a variable stator blade, and the controller controls the variable angle of each variable stator blade to control the impact angle of the pressurized air from the at least one pressurized airflow nozzle on the plurality of rotor blades of the respective compressor rotor.

[0050] The gas turbine engine according to any of the foregoing clauses further includes: (i) a core engine housing disposed radially outside the stator shroud housing, the pressurized air source disposed between the stator shroud housing and the core engine housing; (ii) an intake duct connected to an inlet and to the pressurized air source via the core engine housing; and (iii) a pressurized air duct connecting the pressurized air source to the plurality of pressurized airflow nozzles.

[0051] The gas turbine engine according to any of the foregoing clauses further includes at least one valve disposed in the pressurized air duct to control the flow of pressurized air generated by the pressurized air source to the plurality of pressurized airflow nozzles.

[0052] According to any of the preceding clauses, in a gas turbine engine, the pressurized air source is an air pump, and the controller controls the air pump and the at least one valve during engine shutdown to generate a pressurized airflow, which is provided to the plurality of pressurized airflow nozzles to rotate the compressor rotor shaft assembly.

[0053] According to any of the preceding clauses, in a gas turbine engine, wherein the controller monitors at least one operating condition of the compressor section during the engine shutdown phase to control the air pump and the at least one valve, the at least one operating condition of the compressor section including any one of the compressor section temperature, the rotational speed of the compressor rotor shaft assembly, and the vibration level.

[0054] According to any of the preceding clauses, in a gas turbine engine, the plurality of pressurized airflow nozzles are arranged at the stator housing and direct the pressurized airflow through the stator housing to the plurality of rotor blades of at least one of the plurality of compressor rotors to rotate the compressor rotor shaft assembly.

[0055] According to any of the preceding clauses, in a gas turbine engine, the plurality of pressurized airflow nozzles are arranged in an array circumferentially around the stator casing.

[0056] A gas turbine engine according to any of the foregoing clauses includes a first array of the plurality of pressurized airflow nozzles and a second array of the plurality of pressurized airflow nozzles, the first array and the second array being spaced apart from each other in the longitudinal direction, and the plurality of pressurized airflow nozzles of the first array being circumferentially staggered relative to the plurality of pressurized airflow nozzles of the second array.

[0057] According to any of the preceding clauses, in a gas turbine engine, a plurality of arrays of pressurized airflow nozzles are arranged around the stator shroud housing, each of the plurality of arrays being spaced apart in the longitudinal direction and corresponding to a respective compressor rotor among the plurality of compressor rotors.

[0058] A method of operating a gas turbine engine, the gas turbine engine comprising: (a) a compressor section, the compressor section comprising: (i) a compressor rotor shaft assembly having a plurality of compressor rotors, each compressor rotor including a plurality of rotor blades; and (ii) a stator shroud assembly including a stator shroud surrounding the compressor rotor shaft assembly, a compressor flow passage defined between the compressor rotor shaft assembly and the stator shroud; (b) a pressurized air source generating a pressurized airflow to be supplied to the compressor section; (c) a plurality of pressurized airflow nozzles connected to the pressurized air source and configured to provide the pressurized airflow into the compressor flow passage; and (d) a controller, the method comprising: initiating control of an engine shutdown phase via the controller, the control of the engine shutdown phase comprising: (a) during the start-up... (a) During the engine shutdown phase, the controller checks at least one condition of the compressor section of the gas turbine engine; (b) the controller actuates the pressurized air source based on the result of checking the at least one condition, thereby initiating the supply of pressurized air flow from the pressurized air source to the plurality of pressurized airflow nozzles; (c) the pressurized air flow is directed into the compressor flow passage through the plurality of pressurized airflow nozzles; (d) the compressor rotor shaft assembly is rotated by directing the pressurized air flow into the compressor flow passage; (e) the controller monitors the at least one condition of the compressor section when the compressor rotor shaft assembly rotates; (f) the controller determines whether a threshold of the at least one condition is met during the monitoring; and (g) when the determination determines that the threshold of the at least one condition has been met, the controller terminates the control of the engine shutdown phase.

[0059] According to the method described in the foregoing clause, the at least one condition includes at least one of the temperature at the compressor section and the rotational speed of the compressor rotor shaft assembly.

[0060] According to any of the foregoing clauses, the plurality of pressurized airflow nozzles are arranged to provide the pressurized airflow through the stator shroud and to direct the pressurized airflow onto the plurality of rotor blades of at least one of the plurality of compressor rotors to rotate the compressor rotor shaft assembly.

[0061] According to any of the foregoing claims, the stator shroud assembly includes a plurality of pressurized stator blades, each pressurized stator blade including a stator blade airflow passage therein and at least one of the plurality of pressurized airflow nozzles in fluid communication with the stator blade airflow passage, and in the guiding, the pressurized airflow nozzles of the plurality of pressurized stator blades guide the pressurized airflow to the plurality of rotor blades of at least one of the plurality of compressor rotors to rotate the compressor rotor shaft assembly.

[0062] According to any of the foregoing descriptions, the plurality of pressurized stator blades are variable stator blades capable of angular adjustment about the stator blade axis, and in the guidance, the controller controls the angle of the variable stator blades to adjust the impact angle of the pressurized airflow on the plurality of rotor blades.

[0063] According to any of the foregoing clauses of the method, wherein the compressor rotor shaft assembly defines therein a pressurized chamber in fluid communication with the pressurized air source, and the plurality of pressurized airflow nozzles are arranged through at least one rotor shaft section of the compressor rotor shaft assembly, the plurality of pressurized airflow nozzles being circumferentially spaced and arranged to provide tangential airflow therefrom with respect to the circumferential direction about the compressor rotor shaft assembly, and in the guiding, the plurality of pressurized airflow nozzles guide the pressurized airflow therefrom in the tangential direction into the compressor flow passage to cause the compressor rotor shaft assembly to rotate.

[0064] According to any of the foregoing clauses, the gas turbine engine further includes a piping system connecting the pressurized air source and the plurality of pressurized airflow nozzles, and at least one valve within the piping system; the method further includes the controller controlling the at least one valve based on the at least one condition, and the plurality of pressurized airflow nozzles including a first array of pressurized airflow nozzles corresponding to a first compressor rotor of the plurality of compressor rotors, and a second array of pressurized airflow nozzles corresponding to a second compressor rotor, the at least one valve including a first valve for controlling airflow to the first array of pressurized airflow nozzles, and a second valve for controlling airflow to the second array of pressurized airflow nozzles, the method further including the controller controlling at least one of the first valve and the second valve to be in an open state or in a closed state based on the at least one condition.

[0065] While the foregoing description is directed to some exemplary embodiments of the present disclosure, it should be noted that other changes and modifications will be apparent to those skilled in the art and can be made without departing from the spirit or scope of the present disclosure. Furthermore, features described in connection with one embodiment of the present disclosure may be used in conjunction with other embodiments, even if not explicitly stated above.

Claims

1. A gas turbine engine, characterized in that, include: The compressor section includes: (a) a compressor rotor shaft assembly including a plurality of compressor rotors longitudinally spaced apart from each other via respective shaft segments of a plurality of shaft segments of a rotor shaft, each of the plurality of compressor rotors having a plurality of rotor blades extending radially outward from the compressor rotors and circumferentially spaced around the compressor rotors; and (b) a stator shroud assembly including a stator shroud housing surrounding the compressor rotor shaft assembly, a compressor flow passage defined between the compressor rotor shaft assembly and the stator shroud housing; A pressurized air source that generates a pressurized airflow to be supplied to the compressor section; and Multiple pressurized airflow nozzles are connected to the pressurized air source and provide the pressurized airflow into the compressor flow passage to cause the compressor rotor shaft assembly to rotate; The compressor rotor shaft assembly defines a pressurized chamber in fluid communication with the pressurized air source, and the plurality of pressurized airflow nozzles are arranged through at least one rotor shaft section of the compressor rotor shaft assembly, the plurality of pressurized airflow nozzles being circumferentially spaced and arranged to provide tangential airflow from there to the compressor flow passage relative to the circumferential direction about the compressor rotor shaft assembly, so as to rotate the compressor rotor shaft assembly.

2. The gas turbine engine according to claim 1, characterized in that, The gas turbine engine is installed in the aircraft, and the pressurized air source is any one of the auxiliary power unit installed in the aircraft, the air pump installed in the aircraft, and an air source outside the aircraft and connected to the aircraft during the shutdown phase of the gas turbine engine.

3. The gas turbine engine according to claim 1, characterized in that, The stator shroud assembly includes a plurality of pressurized stator blades, each of the pressurized stator blades including: (i) a stator blade airflow passage within the pressurized stator blade, the stator blade airflow passage being in fluid communication with the pressurized air source; and (ii) at least one of the plurality of pressurized airflow nozzles, the at least one pressurized airflow nozzle being arranged to guide the pressurized airflow onto the plurality of rotor blades of at least one of the plurality of compressor rotors to cause the compressor rotor shaft assembly to rotate.

4. The gas turbine engine according to claim 3, characterized in that, Each of the plurality of pressurized stator blades is a variable stator blade, and the controller controls the variable angle of each variable stator blade to control the impact angle of the pressurized airflow from the at least one pressurized airflow nozzle on the plurality of rotor blades of the corresponding compressor rotor.

5. The gas turbine engine according to claim 1, characterized in that, Further includes: (i) a core engine housing, the core engine housing being disposed radially outside the stator shield housing, and the pressurized air source being disposed between the stator shield housing and the core engine housing; (ii) an intake duct, which is connected to the inlet and the pressurized air source via the core engine housing; and (iii) a pressurized air conduit that connects the pressurized air source to the plurality of pressurized airflow nozzles.

6. The gas turbine engine according to claim 5, characterized in that, It further includes at least one valve disposed in the pressurized air duct to control the flow of pressurized air generated by the pressurized air source to the plurality of pressurized airflow nozzles.

7. The gas turbine engine according to claim 6, characterized in that, The pressurized air source is an air pump, and the controller controls the air pump and the at least one valve during the engine shutdown phase to generate a pressurized airflow, which is provided to the plurality of pressurized airflow nozzles to rotate the compressor rotor shaft assembly.

8. The gas turbine engine according to claim 7, characterized in that, The controller monitors at least one operating condition of the compressor section during the engine shutdown phase to control the air pump and the at least one valve. The at least one operating condition of the compressor section includes any one of the compressor section temperature, the rotational speed of the compressor rotor shaft assembly, and the vibration level.

9. The gas turbine engine according to claim 1, characterized in that, The plurality of pressurized airflow nozzles are arranged at the stator housing and guide the pressurized airflow through the stator housing to the plurality of rotor blades of at least one of the plurality of compressor rotors to rotate the compressor rotor shaft assembly.

10. The gas turbine engine according to claim 9, characterized in that, The plurality of pressurized airflow nozzles are arranged in an array around the stator housing.

11. The gas turbine engine according to claim 10, characterized in that, The device includes a first array of the plurality of pressurized airflow nozzles and a second array of the plurality of pressurized airflow nozzles, the first array and the second array being spaced apart from each other in the longitudinal direction, and the plurality of pressurized airflow nozzles of the first array being circumferentially staggered relative to the plurality of pressurized airflow nozzles of the second array.

12. The gas turbine engine according to claim 10, characterized in that, The plurality of arrays of pressurized airflow nozzles are arranged around the stator housing, each array being spaced apart in the longitudinal direction and corresponding to a respective compressor rotor among the plurality of compressor rotors.

13. A method for operating a gas turbine engine, characterized in that, The gas turbine engine includes: (a) a compressor section, the compressor section including: (i) a compressor rotor shaft assembly having a plurality of compressor rotors, each compressor rotor including a plurality of rotor blades; and (ii) a stator shroud assembly including a stator shroud surrounding the compressor rotor shaft assembly, a compressor flow passage defined between the compressor rotor shaft assembly and the stator shroud; (b) a pressurized air source generating a pressurized airflow to be supplied to the compressor section; (c) a plurality of pressurized airflow nozzles connected to the pressurized air source and configured to provide the pressurized airflow into the compressor flow passage; and (d) a controller, the method including: The engine shutdown phase is initiated via the controller, and the engine shutdown phase control includes: (a) During the engine shutdown phase, the controller checks at least one condition of the compressor section of the gas turbine engine; (b) The controller actuates the pressurized air source based on the result of checking the at least one condition, thereby initiating the supply of pressurized air flow from the pressurized air source to the plurality of pressurized airflow nozzles; (c) The pressurized airflow is guided into the compressor flow passage through the plurality of pressurized airflow nozzles; (d) Rotating the compressor rotor shaft assembly by directing the pressurized airflow into the compressor flow passage; (e) The controller monitors at least one condition of the compressor section when the compressor rotor shaft assembly rotates; (f) The controller determines whether a threshold is met in the monitoring for at least one of the conditions; and (g) When the determination determines that the threshold of at least one of the conditions has been met, the control of the engine shutdown phase is terminated by the controller.

14. The method according to claim 13, characterized in that, The at least one of said conditions includes at least one of the temperature at the compressor section and the rotational speed of the compressor rotor shaft assembly.

15. The method according to claim 13, characterized in that, The plurality of pressurized airflow nozzles are arranged to provide the pressurized airflow through the stator shroud and to direct the pressurized airflow onto the plurality of rotor blades of at least one of the plurality of compressor rotors to rotate the compressor rotor shaft assembly.

16. The method according to claim 13, characterized in that, The stator shroud assembly includes a plurality of pressurized stator blades, each pressurized stator blade including a stator blade airflow passage therein and at least one of the plurality of pressurized airflow nozzles in fluid communication with the stator blade airflow passage, and in the guiding, the pressurized airflow nozzles of the plurality of pressurized stator blades guide the pressurized airflow to the plurality of rotor blades of at least one of the plurality of compressor rotors to cause the compressor rotor shaft assembly to rotate.

17. The method according to claim 16, characterized in that, The plurality of pressurized stator blades are variable stator blades capable of angular adjustment around the stator blade axis, and in the guidance, the controller controls the angle of the variable stator blades to adjust the impact angle of the pressurized airflow on the plurality of rotor blades.

18. The method according to claim 13, characterized in that, The compressor rotor shaft assembly defines a pressurized chamber therein in fluid communication with the pressurized air source, and the plurality of pressurized airflow nozzles are arranged through at least one rotor shaft section of the compressor rotor shaft assembly, the plurality of pressurized airflow nozzles being circumferentially spaced and arranged to provide tangential airflow therefrom with respect to the circumferential direction about the compressor rotor shaft assembly, and in the guidance, the plurality of pressurized airflow nozzles guide the pressurized airflow therefrom in the tangential direction into the compressor flow passage to cause the compressor rotor shaft assembly to rotate.

19. The method according to claim 13, characterized in that, The gas turbine engine further includes a piping system connecting the pressurized air source and the plurality of pressurized airflow nozzles, and at least one valve within the piping system; the method further includes the controller controlling the at least one valve based on the at least one condition, and the plurality of pressurized airflow nozzles including a first array of pressurized airflow nozzles corresponding to a first compressor rotor of the plurality of compressor rotors, and a second array of pressurized airflow nozzles corresponding to a second compressor rotor, the at least one valve including a first valve for controlling airflow to the first array of pressurized airflow nozzles, and a second valve for controlling airflow to the second array of pressurized airflow nozzles, the method further including the controller controlling at least one of the first valve and the second valve to be in an open state or in a closed state based on the at least one condition.

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