Gas turbine engine including embedded electric machine and associated cooling system

Abstract

A method of removing heat from an electric machine located in a gas turbine engine is provided, the electric machine being located at least partially radially inboard of a core airflow path, the electric machine comprising an outer generator stator and an inner generator rotor. The method comprises radially directing a cooling airflow through an airflow path to an outer casing, the outer casing being at least partially defined by a heat shield at least partially surrounding the electric machine. A cooling airflow is directed radially inwardly through the outer generator stator and toward the inner generator rotor using a cooling manifold, thereby removing heat from the generator rotor.

Description

Technical Field

[0001] The present description relates generally to gas turbine engines and, more particularly, to gas turbine engines including embedded electric machines and associated cooling systems for cooling the electric machines. Background Art

[0002] Gas turbine engines are often used as part of an aircraft propulsion system. A gas turbine engine may include a compressor section, a combustion section, a turbine section, and an exhaust section. Air is provided by a fan to the compressor section, where it is compressed and delivered to the combustion section. In the combustion section, the air is mixed with fuel and then burned. The combustion gases are then delivered to the turbine section, which drives the turbine section before delivering the combustion gases to the exhaust section.

[0003] During operation, the temperature within the gas turbine engine may rise. In order to manage the temperature increase of the gas turbine engine, various cooling systems may be provided for removing thermal energy from various components of the gas turbine engine. Certain components of the gas turbine engine may be better at handling the temperature increase than other components. For example, it may be desirable to limit the temperature increase of an electric machine that may be embedded within the gas turbine engine. Summary of the invention

[0004] According to an embodiment of the present disclosure, a method for removing heat from an electric machine located in a gas turbine engine, the electric machine being located at least partially inboard of a core airflow path in a radial direction, the electric machine comprising an outer generator stator and an inner generator rotor. The method comprises radially directing a cooling airflow through an airflow path to a housing, the housing being at least partially defined by a heat shield at least partially around the electric machine. A cooling manifold is used to direct the cooling airflow radially inward through the outer generator stator and toward the inner generator rotor, thereby removing heat from the generator rotor.

[0005] According to another embodiment of the present disclosure, a gas turbine engine includes a compressor section and a turbine section arranged in a serial flow order. The compressor section and the turbine section together define a core airflow path. The rotating component can rotate together with at least a portion of the compressor section and at least a portion of the turbine section. The motor is at least partially located inside the core airflow path in a radial direction. The motor includes an outer generator stator and an inner generator rotor coupled to the rotating component. The heat shield at least partially forms a housing around the motor. The heat shield at least partially defines a cooling airflow path that at least partially surrounds the motor. The cooling manifold guides the cooling airflow received from the airflow passage through the outer generator stator and reaches the inner generator rotor.

[0006] Additional features, embodiments, and advantages of the gas turbine engine and methods of using the same described herein will be set forth in the detailed description that follows, and in part, will be apparent to those skilled in the art based on the teachings disclosed herein and are contemplated and considered within the scope of the present disclosure.

[0007] It should be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the subject matter described and claimed herein. The accompanying drawings are included to provide a further understanding of the various embodiments and are incorporated into and constitute a part of this specification. The accompanying drawings illustrate the various embodiments described herein and, together with the description, serve to explain the principles and operation of the subject matter described and claimed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic cross-sectional view of a gas turbine engine including an electric machine according to one or more embodiments shown and described herein;

[0009] Figure 2 According to one or more embodiments shown and described herein Figure 1 A schematic perspective view of a portion of a gas turbine engine including the location of an electric machine and an electrical system and a cooling system for cooling the electrical system and the electric machine;

[0010] Figure 3 A motor according to one or more embodiments shown and described herein Figure 1 A schematic cross-sectional view of a rear portion of a gas turbine engine;

[0011] Figure 4A A cooling channel according to one or more embodiments shown and described herein Figure 3 A schematic cross-sectional view of a portion of a generator rotor of an electric machine;

[0012] Figure 4B According to one or more embodiments shown and described herein, Figure 4A A schematic cross-sectional view of a portion of a generator rotor having a cooling channel;

[0013] Figure 4C is a method for Figure 1 A schematic cross-sectional view of a portion of an electric machine in a gas turbine engine;

[0014] Figure 5A A cooling system including a cooling system according to one or more embodiments shown and described herein Figure 1 A schematic cross-sectional view of a gas turbine engine;

[0015] Figure 5B According to one or more embodiments shown and described herein Figure 1 A schematic cross-sectional view of another embodiment of a gas turbine engine;

[0016] Fig. 6A is a method for Figure 1 A schematic cross-sectional view of a support of a turbine rear frame in a gas turbine engine;

[0017] Figure 6B is a method for Figure 1 A schematic cross-sectional view of another support of a turbine rear frame in a gas turbine engine;

[0018] Figure 6C is a method for Figure 1 A schematic cross-sectional view of another support of a turbine rear frame in a gas turbine engine;

[0019] Fig.6D is a method for Figure 1 A schematic cross-sectional view of another support of a turbine rear frame in a gas turbine engine;

[0020] Figure 7 is a schematic cross-sectional view of another rear portion of a gas turbine engine and an electric machine according to one or more embodiments shown and described herein; and

[0021] Figure 8 is a schematic cross-sectional view of another rear portion of a gas turbine engine and an electric machine according to one or more embodiments shown and described herein. DETAILED DESCRIPTION

[0022] Embodiments described herein are generally directed to a gas turbine engine including an embedded electric machine and an associated cooling system for cooling the electric machine. The gas turbine engine may include a compressor section and a turbine section arranged in a serial flow order and together defining a core gas flow path. A rotating member (such as a shaft, a spool, etc.) may rotate with at least some portions of the compressor section and the turbine section. The electric machine is embedded in the gas turbine engine. The electric machine may rotate with the rotating member and be coaxially positioned with the rotating member, at least partially inside the core gas flow path in a radial direction of the gas turbine engine. The electric machine may be a generator driven by the rotating member.

[0023] The gas turbine engine includes a cooling system for cooling the electric machine, which may be required due to the rearward position of the electric machine in the gas turbine engine. In particular, the electric machine may be located at least partially inboard of a core airflow path in a radial direction and rearward within a tail cone. A housing may be provided that at least partially surrounds the electric machine. The housing may at least partially define at least one airflow path around the electric machine. The at least one airflow path around the electric machine may receive air from an airflow path provided by struts of a turbine rear frame. A thermal insulation blanket may be provided around and along the airflow path to reduce heat transfer from external exhaust gas leaving the turbine section to cooling air flowing through the airflow path.

[0024] In some embodiments, the gas turbine engine includes a cooling system that directs cooling air to the inner generator rotor of the motor. For example, a cooling plate can be installed on the inner side of the inner generator rotor between the rotating component and the inner generator rotor, and the inner generator rotor is connected to the rotating component so that the inner generator rotor rotates with the rotating component to generate electricity. In some embodiments, the cooling plate can be part of the rotor structure and direct air directly onto the rotor component. In some embodiments, the cooling plate can also be connected to the rotating component so that the cooling plate rotates with the inner generator rotor. The cooling plate is shaped and arranged to direct cooling air received from the airflow passage to the rotor for cooling.

[0025] refer to Figure 1 , the exemplary gas turbine engine 10 may be configured for mounting on a wing or fuselage of an aircraft. In some embodiments, the gas turbine engine 10 may also be used to provide power. The gas turbine engine 10 includes: a fan section 12, which includes a fan 14; a compressor section 16; and a turbine section 18. The fan section 12, the compressor section 16, and the turbine section 18 may include one or more rotor disks 20, one or more rotor disks 20 including rotor blades extending radially therefrom. Air is drawn into the gas turbine engine 10 and accelerated by the fan 14. The air or at least a portion thereof is compressed in the compressor section 16 and delivered to the combustion chamber, where the air is mixed with fuel and combusted, thereby producing hot combustion gases. The combustion gases pass through the turbine section 18, which extracts mechanical work from the combustion gases to rotate the attached compressor section 16, thereby further compressing the upstream air to produce a self-sustaining process. The combustion gases are discharged through the nozzle section 22.

[0026] The gas turbine engine 10 defines an axial direction A extending parallel to a longitudinal centerline 23, a radial direction R extending perpendicular to the axial direction A, and a circumferential direction C extending around the axial direction A. As used herein, the terms "inner" and "outer" are used with reference to the centerline 23, such that inner is closer to the centerline 23 and outer is farther from the centerline 23. The gas turbine engine 10 includes a fan section 12 and a core section 24, which is located downstream of the fan section 12 in the axial direction.

[0027] The gas turbine engine 10 includes a tubular core shroud 30 that at least partially defines an annular inlet 32. The core shroud 30 surrounds, in serial flow relationship: a compressor section 16 that includes a boost or low pressure (LP) compressor 34 and a high pressure (HP) compressor 36; a combustion section 38 that includes a combustion chamber; a turbine section 18 that includes a high pressure (HP) turbine 40 and a low pressure (LP) turbine 42; and an ejection exhaust nozzle section 22. The compressor section 16, the combustion section 38, and the turbine section 18 together define a core gas flow path 44 that extends from the annular inlet 32 ​​through the LP compressor 34, the HP compressor 36, the combustion section 38, and the HP turbine 40. A first shaft or spool 45 drivingly connects the HP turbine 40 to the HP compressor 36. A second shaft or spool 48 drivingly connects the LP turbine 42 to the LP compressor 34 and the fan 14.

[0028] The fan section 12 includes a fan 14 having a plurality of fan blades 46 coupled to a disk 49 in a spaced apart manner. The fan blades 46 extend outwardly from the disk 49 generally in a radial direction R. The disk 49 is covered by a rotatable front hub 50 that is aerodynamically shaped to facilitate air flow through the plurality of fan blades 46. The exemplary fan section 12 includes an annular fan casing or outer nacelle 52 that circumferentially surrounds at least a portion of the fan 14 and / or the core section 24. The outer nacelle 52 is supported relative to the core section 24 by a plurality of circumferentially spaced apart struts that also serve as outlet guide vanes 54. A downstream section 56 of the outer nacelle 52 extends over an outer portion of the core cowl 30 to define a bypass airflow passage 58 therebetween.

[0029] The gas turbine engine 10 includes an electric motor 60 that can rotate with the fan 14 and is located within the tail cone 65. The electric motor 60 can be a generator coaxially mounted with the second shaft 48 and can rotate with the second shaft 48. The electric motor 60 can be used as an electric motor that converts electrical energy into mechanical energy. In some embodiments, the axis of the electric motor 60 can be radially offset from the axis of the second shaft 48 and can also be tilted to the axis of the second shaft 48, so that the electric motor 60 can be positioned at any suitable position at least partially inside the core airflow path 44. In some embodiments, the electric motor 60 can rotate with the first shaft 45.

[0030] Figure 1 The gas turbine engine 10 depicted in FIG. 1 is provided as an example only. In other exemplary embodiments, the gas turbine engine 10 may be replaced with other types of gas turbine engines utilizing embedded electric machines without loss of clarity. Examples include turboprop engines, turbojets, open rotor or non-ducted fan engines.

[0031] refer to Figure 2 , a perspective view of a portion of the gas turbine engine 10 is schematically shown and generally describes an electrical system 62 and a cooling system 64. The electrical system 62 includes a plurality of components disposed in the gas turbine engine 10 ( Figure 1 ). The rear section 66 is disposed axially downstream of the core section 24 of the gas turbine engine 10. The motor 60 converts mechanical energy generated by the gas turbine engine 10 (e.g., generated by exhaust gas generated in the core section 24) into electrical energy, which can be used to power electrical devices of the gas turbine engine 10 or components disposed elsewhere on the aircraft incorporating the gas turbine engine 10. Positioning the motor 60 in the rear section 66 of the gas turbine engine 10 can make the motor 60 easy to maintain, repair, and replace. The motor 60 can be integrated into the gas turbine engine 10 via a set of connections that can be removed without invasively disassembling the entire gas turbine engine 10, such as without removing the gas turbine engine 10 from the wing of the aircraft.

[0032] Positioning the motor 60 in the rear portion 66 provides accessibility, but creates additional design considerations for the gas turbine engine 10. The exhaust gas produced by the core section 24 may be at a relatively high temperature (e.g., in excess of about 700° C. or higher in various embodiments), which may make cooling the motor 60 beneficial. Additionally, the rear portion 66 of the gas turbine engine 10 may not be directly connected to the aircraft in which the gas turbine engine 10 is incorporated (e.g., the gas turbine engine 10 may be connected to the aircraft via an external nacelle 52 ( Figure 1 ) is connected to the wing of the aircraft by a pylon extending therefrom, with the nacelle 52 being arranged radially outward from the core section 24). In view of this, in order to provide the electricity generated by the electric motor 60 to other parts of the aircraft, the electricity is directed through the gas turbine engine 10.

[0033] In view of the foregoing, the electrical system 62 includes a connection assembly 70 that is directed through the cooling system 64. The connection assembly 70 includes a plurality of electrical connectors 73 (e.g., power cables) that conductively connect the motor 60 to the converter 72. For example, the motor 60 can generate an alternating current ("AC") power signal from the mechanical energy in the rotating LP shaft 48, and the power is directed to the converter 72 (located in the front portion of the engine) via the connection assembly 70. The converter 72 can generate a DC voltage from the AC power signal for communication with an alternative location on the aircraft (e.g., via an electrical communication bus). The structure of the converter 72 and the connection assembly 70 can vary depending at least in part on the structure and capabilities of the motor 60. For example, in various embodiments, the motor 60 can generate an AC power signal having any number of phases (e.g., one phase, two phases, three phases, four phases, etc.).

[0034] The cooling system 64 directs cooling air from an air source to the electric machine 60 to maintain the electric machine 60 within a desired temperature range despite the fact that the electric machine 60 is disposed in proximity to the relatively high temperature exhaust gas generated by the core section 24. The cooling system 64 may include a valve assembly 74 in fluid communication with the air source (see also FIG. Figure 5A ). In an embodiment, the valve assembly 74 can be controlled by a controller (e.g., FADEC controlled), or it can be started within a preset time period during or after engine shutdown. Based on a temperature sensor near the motor or elsewhere in the core housing, the blower can be operated for a period of time instead. When the blower is started (during or after shutdown), the valve assembly 74 is opened and cooling air is drawn into the cooling system 64. The cooling system 64 can also include a bypass duct 76 that can be used to bypass the valve assembly 74. The cooling blower assembly 81 can be controlled via a controller to operate during the time period when the valve assembly 74 is closed. Regardless of the operating state of the gas turbine engine 10, the bypass duct 76 and the cooling blower assembly 81 can be used to provide cooling air to the motor 60. The cooling blower assembly 81 can be powered by the aircraft or another power source specifically for use by the cooling blower assembly 81.

[0035] The cooling system 64 may include a plurality of different ducts having structures extending in different directions at various locations within the gas turbine engine 10. As shown, the cooling system 64 includes a main duct 78, a circumferential duct 80, and a plurality of generator cooling ducts 82, which may or may not continue through struts 88 (i.e., the struts 88 may have their own airflow paths; see FIG. Figures 6A-6D The main duct 78 , the circumferential duct 80 , and the plurality of generator cooling ducts 82 may be designed to provide sufficient space for directing the connection assembly 70 to the electric machine 60 while reducing the impact on the aerodynamic performance of the gas turbine engine 10 .

[0036] The valve assembly 74 controls the airflow through the main duct 78. The main duct 78 directs the cooling air to the rear portion 66 where the motor 60 is located. The circumferential duct 80 divides the cooling air into circumferential portions and directs the cooling air in a circumferential direction around the turbine rear frame 86. In an embodiment, a plurality of generator cooling ducts 82 divide each circumferential portion of the cooling air into cooling portions, and the cooling portions are provided to the motor 60 via the struts 88 of the turbine rear frame 86. In some embodiments, the cooling system 64 includes four generator cooling ducts 82, which provide cooling air to the motor 60 via four separate struts 88 of the turbine rear frame 86. It should be noted that any suitable existing structure of the gas turbine engine 10 can be made into a cooling duct that is configured to direct the cooling air to a desired location. In an embodiment, the generator cooling duct 82 extends through the strut 88 into a generator coupler that is in fluid communication with the motor 60 to cool the motor 60. Each generator cooling duct 82 can be attached to one of the outer ends 90 of the strut 88 to provide cooling air to the inner cavity defined by the strut 88 to which the generator duct 82 is attached. The struts 88 may be airfoil-shaped and provide structural rigidity between the core cowl 30 and the internal components of the engine core, as well as redirecting the airflow exiting the engine core from an angular or swirl direction to an axial direction as it is exhausted.

[0037] The electrical connectors 73 of the connection assembly 70 extend through the main duct 78, the circumferential duct 80, the plurality of generator cooling ducts 82, and the struts 88 of the turbine aft frame 86 to conductively connect the converter 72 to the electric machine 60. In an embodiment, the various sets of electrical connectors of the electrical connection assembly 70 extend through different combinations of ducts of the cooling system 64 to connect different portions (e.g., terminals) of the electric machine 60 to the converter 72. For example, a first subset 92 of electrical connectors may be directed through a first portion of the circumferential duct 80, and a second subset 94 of electrical connectors may be directed through a second portion of the circumferential duct 80. The first subset 92 of electrical connectors and the second subset 94 of electrical connectors may be further divided such that a baseline set of electrical connectors 96 are directed through each generator duct 82, through one of the struts 88, and into the generator coupler to electrically connect to the electric machine 60.

[0038] refer to Figure 3, shows an electric machine 60 embedded within the turbine section 18 of the gas turbine engine 10, and in particular, the tail cone 65. The electric machine 60 is attached to the second shaft 48 via a generator rotor subassembly 100. The electric machine 60 includes the generator rotor subassembly 100 and the generator stator subassembly 102. The generator rotor subassembly 100 includes a rotor support member 106, which is connected to the second shaft 48 at a connection 112. The release of the connection 112 can facilitate the removal of the generator rotor subassembly 100 from the rear 66 of the gas turbine engine 10. The rotor support member 106 includes a radial portion 107 and an axial portion 109. In some embodiments, the axial portion 109 can be formed to allow cooling airflow to flow directly into the inner generator rotor 104, as shown by arrow 111, as will be described in further detail below.

[0039] The generator stator subassembly 102 includes an outer generator stator 124 fixedly connected to a stationary support assembly 125 including a stator support member 126. The stationary support assembly 125 also includes a cooling jacket 132 between the stator support member 126 and the outer generator stator 124, the cooling jacket 132 including a plurality of coolant cavities represented by elements 133 that can receive a coolant liquid (e.g., oil) from a liquid coolant source for controlling the temperature of the outer generator stator 124 during operation.

[0040] The generator rotor subassembly 100 and the generator stator subassembly 102 both include cooling manifolds 140 and 142 that at least partially surround their respective inner generator rotor 104 and outer generator stator 124. The inner cooling manifold 140 is mounted to a stationary support structure 144, which in turn is mounted to the shaft 48 using bearings 146, and is also mounted to the turbine aft frame 86 at an opposite end 148. The support structure 144 is also shown mounted to the stator support member 126 at a connection 150. Release of the connection 150 may facilitate removal of the generator stator subassembly 102 from the aft portion 66 of the gas turbine engine 10.

[0041] The inner cooling manifold 140 extends radially from the support structure 144 to an inner cooling plate 152. The inner cooling plate 152 extends axially and radially below the inner generator rotor 104. A space is provided between the inner generator rotor 104 and the inner cooling plate 152 to provide an airflow passage 154 therebetween so that a cooling airflow 156 can be directed to the inner generator rotor 104. In some embodiments, the inner cooling plate 152 can be mounted to the shaft 48 and / or the inner generator rotor 104 (e.g., using the rotor support member 106) to rotate therewith.

[0042] Brief reference Figure 4AAs an example, an embodiment of the inner generator rotor 104 is shown that includes ducts 202 that provide cooling airflow to various cooling ducts 203 (e.g., which may form the airflow passage 154). The cooling ducts 203 may be axially and / or radially oriented and may send airflow directly to components of the inner generator rotor 104, such as surface mounted permanent magnets, such as Figure 4B As shown. Figure 4B In the example of , the cooling duct 203 may be connected to or formed as part of the rotor disk 205. The rotor disk 205 may include surface mounted permanent magnets (SPM) 209 on opposite sides of the cooling duct 203. As another example, Figure 4C A radial chimney 204 is shown which directs airflow from the passage 154 through the generator rotor between the magnets 209 and to the gap between the generator rotor 102 and the outer generator stator 124 where the cooling airflow can travel away from the machine. Figure 3 As shown, seals 206 (e.g., labyrinth seals) may be used to adjust the airflow rate through the radially extending flues 204 and / or cooling ducts 203. In other embodiments, seals 206 may not be used and the airflow rate may be controlled by the number and size of openings through the cooling manifold 140.

[0043] Reference again Figure 3 , a radial portion 160 of the inner cooling manifold 140 extends radially outward from the inner cooling plate 152 and extends around the end winding 158, connected to the stationary support assembly 125. As will be described in more detail below, the inner cooling manifold 140 includes airflow openings (represented by elements 162 and 164) that divide the incoming cooling airflow 166 into multiple cooling airflows 156 and 168 that impinge on the end winding 158. The seal 206 can also be used to control the airflow rate between the cooling airflows 156 and 168. In other embodiments, the seal 206 may be absent and the number and diameter of the openings 162 and 164 may be used to control the airflow split. For example, the airflow rates of the cooling airflows 156 and 168 may be different or they may be approximately the same.

[0044] The outer cooling manifold 142 is also mounted to the stationary support assembly 125. In some embodiments, the outer cooling manifold 142 and the inner cooling manifold 140 may be part of the same manifold structure and may be mounted in different configurations. Figure 3 In some embodiments, the outer cooling manifold 142 and the inner cooling manifold 140 may be separate structures that are indirectly connected together, such as through the stationary support assembly 125. The outer cooling manifold 142 includes airflow openings (represented by elements 169) that allow the cooling airflow 172 to impinge on the end windings 174.

[0045] Heat shield 176 defines housing 178 that extends from coupling 159 that is axially and radially coupled to turbine aft frame 86 about electric machine 60. Heat shield 176 may be formed of any suitable material (e.g., ceramic, aluminum, steel, etc.). As used herein, "heat shield" refers to a structure that effectively reduces one or more of convective, conductive, and radiative heat transfer to electric machine 60.

[0046] The duct assembly 180 is connected to the coupler 159. The duct assembly 180 includes a first duct structure 184 and a second duct structure 188, the first duct structure 184 being connected to the coupler 159 via a duct support bracket 186, and the second duct structure 188 being also connected to the coupler 159 via the duct support bracket 186, so that the first duct structure 184 and the second duct structure 188 are in fluid communication. Seals represented by elements 190 and 192 may be provided to provide an airtight seal between the duct structures 184 and 188. The duct support bracket 186 may include openings represented by elements 187 and 189 that allow airflow between the first duct structure 184 and the second duct structure 188.

[0047] The first duct structure 184 is fluidly connected to an air passage 194 extending through the struts 88. The first duct structure 184 leads to one or more outlets 196 that provide the cooling airflow 166 to the inner cooling manifold 140. The second duct structure 188 is fluidly connected to the first duct structure 184. The second duct structure 188 includes one or more outlets 198 that provide the cooling airflow 172 to the outer cooling manifold 142.

[0048] The inner generator rotor 104 and the outer generator stator 124 operate together to generate electricity as the second shaft 48 rotates during engine operation. In some embodiments, the inner generator rotor 104 includes a plurality of permanent magnets distributed circumferentially around the outer generator stator 124, so that the rotation of the inner generator rotor 104 around the outer generator stator 124 generates an AC power signal. The outer generator stator 124 may include a plurality of windings conductively connected to an electrical connector 212 via conductors 210. The electrical connector 212 may be supported by a pipe support bracket 186 connected to the coupling 159.

[0049] The electrical connector 212 is an electrical coupling configured to provide a conductive connection between the electrical connector 212 electrically coupled to the outer generator stator 124 and the electrical wire 170. For example, the electrical wire 170 may be directed through one of the struts 88 of the turbine aft frame 86. The electrical connector 212 may have a first portion 216 located in the first duct structure 184 and a second portion 218 located in the second duct structure 188. As will be further described below, the duct assembly 180 may be used to direct cooling air into and through the housing 178 to remove heat from the electric machine 60.

[0050] refer to Figure 5A As described above, the gas turbine engine 10 includes a cooling system 64 for removing heat from the electric machine 60. The cooling system 64 includes a valve assembly 74 that controls the flow of cooling air from an air source (e.g., from the compressor section 16 and / or the fan section 12). In particular, Figure 5A An embodiment of a core section 24 of a gas turbine engine 10 is shown with the fan section 12 adjacent the core section 24. The HP compressor 36 includes multiple stages of rotating blades and stationary buckets all surrounded by a compressor casing.

[0051] The gas turbine engine 10 may optionally incorporate a variable bleed valve ("VBV") system for controlling the stall margin of the supercharger. The VBV system includes one or more variable bleed valves 220 mounted within a fan hub frame 222. The variable bleed valve 220 is opened during low power operation of the gas turbine engine 10 (e.g., at idle) to bleed a portion of the compressed air. The variable bleed valve 220 may be closed during high power operation of the gas turbine engine 10 (e.g., during cruise or takeoff) because bleed may not be required. When the variable bleed valve 220 is open, air passes from the supercharged flow path through the fan hub frame 222 and into the bypass duct, or more generally into the bypass space outside the cowling 30. In the illustrated example, the engine 10 includes at least one bypass duct 226 that defines an airflow path from the fan hub frame 222 to a bleed port 224 that communicates with the bypass airflow passage 58. In some embodiments, the main duct 78 may be communicatively connected to the bypass duct 226 to receive cooling air therefrom. In some embodiments, main duct 78 may be connected to a location upstream of compressor section 16 to receive cooling air therefrom.

[0052] The cooling system 64 includes a main duct 78, which can be communicatively connected to a bypass duct 226. The bypass duct 226 is provided to draw air from the fan toward the bypass airflow passage 58. The extracted air can be used as cooling air because the temperature of the cooling air is lower than the operating temperature in the rear portion 66 where there is no cooling air. In particular, the cooling air can be used to cool the tail cone 65 ( Figure 3 ) in the motor 60.

[0053] The engine core section 24 is surrounded by (contained within) a core cowl 30 which defines an inner boundary of a bypass airflow passage 58 through which fan bypass air flows. Shown is a ducted turbofan that includes a fan 14 or one of a plurality of fans surrounded by an outer nacelle 52 which is spaced apart from the core cowl 30 and defines an outer boundary of the bypass airflow passage 58. In this example, the bypass airflow passage 58 may also be referred to as a "fan duct." Alternatively, in the case of an open rotor engine, there would be no outer nacelle 52 and the bypass airflow passage 58 would be defined only by the outer surface of the core cowl 30. The space inside the core cowl 30 is referred to as an "under-hood space" 232. In practice, the under-hood space 232 may be provided, for example, by vents 233 (at Figure 1 For purposes of this disclosure, what is referred to as the engine interior refers to what is located within the space surrounded by the outer nacelle 52 or core cowling 30 (in the case of an open rotor engine, for example, where the outer nacelle 52 is not present).

[0054] The main duct 78 may be located completely or at least partially within the underhood space 232. The main duct 78 has one or more inlets, represented by element 234, in fluid communication with the bypass duct 226. In some embodiments, the inlet 234 of the main duct 78 is directly connected to the bypass airflow channel 58, whether or not connected to the bypass duct 226. The main duct 78 also has an outlet, represented by element 236, in fluid communication with the circumferential duct 80, which is connected to a plurality of generator cooling ducts 82 ( Figure 2 ) fluid connected.

[0055] The valve assembly 74 can be incorporated in the main conduit 78 and include one or more valves that are operable to control the flow of air through the main conduit 78. As an example, the valve assembly 74 can include a valve 238, which can be a controllable valve that includes a flow control element that can be moved between an open and closed configuration. In the open configuration, the air flow through the main conduit 78 is allowed by the flow control element, and in the closed configuration, the air flow through the main conduit 78 is inhibited by the flow control element. In some embodiments, the valve 238 can have a variable intermediate configuration that allows the air flow to be adjusted to a selected air flow rate between a predetermined minimum and maximum flow rate. As an example, the valve 238 can allow up to about 100% (e.g., up to about 70%, such as up to about 50%, such as up to about 25%, such as up to about 10%, such as about 10% to about 90%, such as about 30% to about 70%) of the total flow rate of cooling air from the bypass conduit 226 during normal engine operation through the main conduit 78.

[0056] The bypass conduit 76 may have an inlet 240 that is fluidly connected to the main conduit 78 at a location upstream of the valve assembly 74. The bypass conduit 76 may have an outlet 242 that is fluidly connected to the main conduit 78 at a location downstream of the valve assembly 74. The inlet 240 and outlet 242 of the bypass conduit 76 may be on opposite sides of the valve assembly 74 so that the cooling air flow can bypass the valve assembly 74 when the valve 238 is in the closed configuration.

[0057] The bypass duct 76 includes a cooling blower assembly 81 between the inlet 240 and the outlet 242. The cooling blower assembly 81 can be any device that can be operated to blow, pump or move the cooling air flow from the inlet 240 to the outlet 242. The power source for operating the cooling blower assembly 81 can be mechanical, hydraulic, pneumatic or electric. For example, the blower rotor can be connected to an electric motor. In one example, the electric motor can be an AC induction motor or a DC motor. The electric motor can utilize a power source provided by the aircraft, or it can utilize its own power source, for example, a power source inside the cooling blower assembly. In addition, the size of the cooling blower assembly 81 can be designed to provide sufficient discharge pressure and flow rate for cooling the motor 60, which can depend at least in part on the size of the gas turbine engine. In addition, the speed of the cooling blower assembly 81 can be controlled so as to change the air speed automatically and / or in response to user input. For example, the volumetric air flow rate provided by the cooling blower assembly 81 can be about 1m 3 / min (50cfm) to about 28.3m 3 / min(1000cfm) anywhere between.

[0058] When the gas turbine engine 10 is operating, the valve assembly 74 is in an open configuration and the blower assembly 81 is inactive. The bypass duct 76 is pressurized with cooling air from the bypass duct 226 and / or the bypass air flow passage 58. The cooling air travels through the valve assembly 74, into the circumferential duct 80, and then through the generator cooling duct 82 ( Figure 2 ). Figure 5A An embodiment is shown in which the converter 72 is located in the bypass air flow passage 58 . Figure 5B Another embodiment is shown where the converter 72 is located within the nacelle 52 .

[0059] Figure 3 A cooling air flow 166 is shown flowing through one of the struts 88 and flowing alongside the electrical wires 170. In some embodiments, a layer of thermal insulation may be provided along the struts 88. Figures 6A-6D Various embodiments of struts 88 are schematically illustrated including thermal insulation 246 that may further insulate cooling airflow 166 flowing through the struts from ambient exhaust gas from the engine turbine. Fig. 6AA thermal insulation layer 246a is shown located on the inner surface of the outer wall 248a and in direct contact with the cooling air flow. Figure 6B Insulation layer 246b is shown positioned on an outer surface of an interior passage wall 250b that defines a passage 252 within an opening 254 through support post 88b. Figure 6C A thermal insulation layer 246c is shown located on the inner surface of the inner passage wall 250c. Fig.6D An insulating layer 246d is shown located on the outer surface of the outer wall 248d. Figures 6A-6D Various insulation placement examples are shown, and other examples are contemplated, including Figures 6A-6D In addition, any suitable material (e.g., titanium alloy, iron-nickel alloy, advanced low CTE superalloy, ceramic, etc.) can be used to form the thermal insulation layer, either as a thermal blanket and / or applied as a coating.

[0060] Reference again Figure 3 , the cooling airflow 166 can remove heat from the wires 170 and then flow into the first duct structure 184 of the duct assembly 180. The first duct structure 184 includes an outlet 196 that provides the cooling airflow 166 to the inner cooling manifold 140. The first duct structure 184 includes another outlet 255 connected to the duct support bracket 186 so that the cooling airflow 166 is supplied to the second duct structure 188. It can be seen that the first duct structure divides the cooling airflow 166 into a plurality of cooling airflows 166a and 166b. The cooling airflow 166a is directed through the outer generator stator 124, through one or more openings 256 in the support structure 144, and then divided into a plurality of cooling airflows 156 and 168 by the inner cooling manifold 140. As described above, the cooling airflow 156 is directed along the airflow path 154 between the cooling plate 152 and the inner generator rotor 104, thereby removing heat from the inner generator rotor 104. The cooling air can then be directed to impinge on the end windings 158 of the outer generator stator 124. The cooling airflow 168 flows through the inner cooling manifold 140 along a different path and directly impinges on the end windings 158 without flowing through the inner generator rotor 104. For example, when there is no seal 206, the seals 206 and / or the number and diameter of the openings 162, 164 can be used to control the percentage of the airflow 166a that forms the cooling airflows 156 and 168. Once in the inner cooling manifold 140, the cooling air can also travel through the gap 250 between the inner generator rotor 104 and the outer generator stator 124 and remove heat from the electric machine 60, particularly from components (e.g., magnets) of the generator rotor subassembly 100.

[0061] The cooling airflow 166b is directed from the first duct structure 184 to the second duct structure 188 and over the electrical connector 212. In the illustrated embodiment, the cooling airflow 166b is not split into multiple airflows as the cooling airflow 166a is, but is directed out of the outlet 198 and into the outer cooling manifold 142. The cooling airflow 166b then exits the outer cooling manifold 142 through the opening 169 and impinges on the end windings 174.

[0062] The spent cooling air streams 156, 168, and 166b may then meet and be directed out of the housing 178 along different paths. As used herein, the term "spent cooling air stream" refers to cooling air that has had heat removed from the motor 60. The spent cooling air stream, even though heat has been removed from the motor 60, may still have a sufficiently low temperature to provide a thermal buffer between the motor 60 and the exhaust gas flowing out of the tail cone 65.

[0063] Some of the spent cooling airflow 257 may flow directly out of the opening 256 in the heat shield 176 and out of the tail cone 65. Another spent cooling airflow 258 may be directed forward by the heat shield 176 partially around the motor, thereby forming an airflow buffer cavity 260. The spent cooling airflow 258 may then be directed back through the struts 88 (as shown by spent cooling airflow 262) and / or directed out of the rear of the tail cone 65 (as shown by spent cooling airflow 264), forming another airflow buffer cavity 266 radially spaced from the airflow buffer cavity 260.

[0064] Various manifolds, ducts, and other air flow devices may be used to direct flow over and through the inner generator rotor 104. For example, Figure 7 Another simplified example of using an accelerator 270 that changes the direction of airflow is illustrated. Figure 7 Many of the components discussed above are included, including the generator rotor 274, the generator stator 276, the heat shield 278, etc. The manifold and ducting assemblies are largely omitted for simplicity, but the cooling airflow 278 arrangement is shown, in which the cooling airflow 279 is directed to the generator rotor 274 and also hits the end windings 280 of the generator stator 276. The accelerator 270 is a structure similar to an impeller or fin that moves the cooling airflow more circumferentially. The accelerator 270 can be stationary, or the accelerator 270 can rotate with the shaft 272, for example. In some embodiments, the accelerator 270 can be mounted to the rotor support member 275 and the inner generator rotor 274 and rotate with it. In the illustrated embodiment, the inner cooling plate 281 is mounted to the rotor support member 275 and rotates with it, thereby generating a circumferential flow of increased cooling airflow.

[0065] The flow paths of the new and spent cooling air streams may be selected depending on the engine architecture and the desired cooling characteristics. For example, Figure 8An embodiment is shown in which the majority of the cooling airflow 282 that enters the housing 284 through the air passages 285 and struts 287 is directed along electrical wires 289 to an electrical connector 286 located at the rear of the motor 288 and then directed to the end windings 290 of the generator stator 294 and the generator rotor 292. In this embodiment, the cooling airflow 282 is directed from the electrical connector 286 and split between the front and rear sides of the motor 288. In some embodiments, an accelerator may be added radially inwardly of the generator rotor 292 or elsewhere to introduce more circumferential flow vectors into the cooling airflow flowing to the generator rotor 292.

[0066] The jet turbine engine described above includes a cooling system that helps remove heat from the motor (e.g., the generator assembly) and creates multiple thermal barriers to reduce external heat loads on the motor. The cooling system may include a duct assembly that directs cooling airflow to a desired location, such as toward the end windings of the generator rotor and the generator stator. The duct assembly and the cooling manifold may be used to preselect a flow pattern so as to provide refreshed and used cooling air to a desired location. In addition, the generator rotor may be provided with airflow passages, cooling plates, etc. that facilitate cooling air to reach internal components of the generator rotor. Such cooling channels may amplify the internal cooling effect of the cooling airflow passing through and through the generator rotor.

[0067] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" component includes aspects having two or more such components unless the context clearly dictates otherwise.

[0068] Scope can be expressed as from "about" a specific value in this article, and / or to "about" another specific value. When expressing such a scope, another embodiment includes from a specific value and / or to another specific value. Similarly, when a value is expressed as an approximation, by using the antecedent "about", it will be understood that the specific value forms another embodiment. It will be further understood that the endpoints of each scope are important with respect to the other endpoint and independently of the other endpoint. The term "about" can be included in any value within ten percent of a specific value (e.g., within five percent of a specific value, such as within two percent of a specific value, such as within one percent of a specific value).

[0069] Directional terms used herein, such as up, down, right, left, front, rear, top, bottom, above, below, are made only with reference to the drawings drawn and are not intended to imply an absolute orientation unless otherwise expressly stated. The terms "axial" and "longitudinal" both refer to directions parallel to the centerline of the gas turbine engine, while "radial" refers to directions perpendicular to the longitudinal direction. The terms "tangential" and "circumferential" refer to directions that are mutually perpendicular to the radial and longitudinal directions. The terms "forward" or "front" refer to an upstream position in the airflow through or around a component during operation, while the terms "rearward" or "rear" refer to a downstream position during operation. These directional terms are used for convenience of description only, and no specific orientation of the structures described thereby is required.

[0070] Unless otherwise expressly stated, any method described herein is in no way intended to be construed as requiring that its steps be performed in a particular order, nor is it intended to require any particular orientation of the apparatus. Thus, in any respect, if a method claim does not actually recite the order in which its steps are to be followed, or any apparatus claim does not actually recite the order or orientation of individual components, or if the claim or description does not otherwise specifically state that the steps are to be limited to a particular order, or if a particular order or orientation of components of the apparatus is not recited, then no order or orientation is intended to be inferred. This applies to any possible non-explicit basis for interpretation, including: problems of logic relating to arrangement of steps, operational flow, order of components, or orientation of components; plain meaning derived from grammatical organization or punctuation; and the number or type of embodiments described in the specification.

[0071] Further aspects are provided by the subject matter in the following clauses:

[0072] Item 1: A method for removing heat from an electric machine located in a gas turbine engine, the electric machine being located at least partially inboard of a core airflow path in a radial direction, the electric machine comprising an outer generator stator and an inner generator rotor, the method comprising: radially directing a cooling airflow through an airflow passage to an outer casing, the outer casing being at least partially defined by a heat shield at least partially surrounding the electric machine; and using a cooling manifold to direct the cooling airflow radially inward through the outer generator stator and toward the inner generator rotor, thereby removing heat from the generator rotor.

[0073] Clause 2: The method of any preceding clause, further comprising directing the cooling airflow radially through radially extending channels of the inner generator rotor.

[0074] Clause 3: The method of any preceding clause, wherein the inner generator rotor comprises a plurality of radially extending channels that direct the cooling airflow radially outward toward a gap between the inner generator rotor and the outer generator stator.

[0075] Clause 4: A method according to any of the above clauses, wherein the cooling manifold is mounted to a stationary support structure, the cooling manifold includes an axially extending cooling plate, the axially extending cooling plate is located radially inwardly of the inner generator rotor to define another air flow path, and the method includes axially directing the cooling air flow through the other air flow path.

[0076] Clause 5: The method of any preceding clause, further comprising limiting the flow rate of the cooling air flow through the another air flow passage using a seal.

[0077] Clause 6: The method of any preceding clause, wherein a flow rate of the cooling airflow through the another airflow passage is restricted using one or more openings through the cooling manifold, the one or more openings having a diameter sized to restrict the cooling airflow.

[0078] Clause 7: The method of any preceding clause, wherein the inner generator rotor comprises a rotor disk including a plurality of surface mounted permanent magnets and an axially extending cooling duct receiving the cooling air flow.

[0079] Clause 8: The method of any preceding clause, wherein the cooling conduit extends axially between adjacent permanent magnets.

[0080] Clause 9: A method according to any preceding clause, wherein the inner generator rotor comprises a rotor disk including radially extending channels, the method comprising directing the cooling airflow into a gap between the inner generator rotor and the outer generator stator.

[0081] Clause 10: A method according to any of the above clauses, wherein the cooling manifold includes a radial portion extending alongside the generator rotor, the radial portion directing the cooling air flow towards the end windings of the outer generator stator and directing the spent cooling air into the gap between the inner generator rotor and the outer generator stator.

[0082] Clause 11: The method of any preceding clause, further comprising an accelerator located radially inwardly of the inner generator rotor and coupled to the rotating member, the accelerator moving the cooling airflow in a circumferential direction as the cooling airflow approaches the inner generator rotor.

[0083] Item 12: The method of claim 1 further comprising an axially extending cooling plate located radially inwardly of the inner generator rotor to define another airflow path that rotates with the inner generator rotor, the method comprising axially directing the cooling airflow through the another airflow path.

[0084] Item 13: A gas turbine engine comprising: a compressor section and a turbine section, the compressor section and the turbine section being arranged in a serial flow order, the compressor section and the turbine section together defining a core airflow path; a rotating component, the rotating component being capable of rotating together with at least a portion of the compressor section and at least a portion of the turbine section; an electric machine, the electric machine being at least partially located on the inner side of the core airflow path in a radial direction, the electric machine comprising an outer generator stator and an inner generator rotor coupled to the rotating component; a heat shield, the heat shield at least partially forming a casing around the electric machine, the heat shield at least partially defining a cooling airflow path, the cooling airflow path at least partially surrounding the electric machine; and a cooling manifold, the cooling manifold directing a cooling airflow received from an airflow passage through the outer generator stator and to the inner generator rotor.

[0085] Clause 14: The gas turbine engine of claim 12, further comprising a cooling plate inwardly adjacent said inner generator rotor, said cooling plate having radially extending channels that direct said cooling airflow radially outwardly toward said inner generator rotor.

[0086] Clause 15: The gas turbine engine of any preceding clause, wherein the cooling plate comprises a plurality of radially extending channels that direct the cooling airflow radially outward toward the inner generator rotor.

[0087] Item 16: A gas turbine engine according to any of the above items, wherein the cooling manifold is mounted to a stationary support structure, the cooling manifold includes an axially extending portion, the axially extending portion is located radially inwardly of the cooling plate, thereby defining another airflow path, the other airflow path axially directing the cooling airflow between the cooling plate and the axially extending portion of the cooling manifold.

[0088] Item 17: A gas turbine engine according to any of the above items, wherein the cooling manifold is mounted to a stationary support structure, the cooling manifold including an axially extending portion, the axially extending portion being located radially inward of the inner generator rotor, thereby defining another airflow passage, the other airflow passage axially directing the cooling airflow between the inner generator rotor and the axially extending portion of the cooling manifold.

[0089] Clause 18: The gas turbine engine of any preceding clause, further comprising a seal in said another gas flow passage, said seal thereby limiting a flow rate of said cooling gas flow.

[0090] Clause 19: The gas turbine engine of any preceding clause, wherein the inner generator rotor comprises a rotor disk including a plurality of surface mounted permanent magnets and an axially extending cooling duct receiving the cooling air flow.

[0091] Clause 20: The gas turbine engine of any preceding clause, wherein the cooling duct extends axially between adjacent permanent magnets.

[0092] Clause 21: The gas turbine engine of any preceding clause, wherein the inner generator rotor comprises a rotor disk including radially extending channels that direct the cooling air to a gap between the inner generator rotor and the outer generator stator.

[0093] Item 22: A gas turbine engine according to any of the above items, wherein the cooling manifold includes a radial portion that extends alongside the inner generator rotor and directs the cooling air flow toward the end windings of the outer generator stator and directs the spent cooling air into the gap between the inner generator rotor and the outer generator stator.

[0094] Clause 23: The gas turbine engine according to any preceding clause, further comprising an accelerator located radially inward of the inner generator rotor and coupled to the rotating member, the accelerator being configured to move the cooling air in a circumferential direction as the cooling airflow approaches the inner generator rotor.

[0095] Clause 24: The gas turbine engine of any preceding clause, wherein the strut includes a thermal insulation layer surrounding and along the airflow passage, the airflow passage extending radially through the strut.

[0096] It will be apparent to those skilled in the art that various modifications and changes may be made to the embodiments described herein without departing from the spirit and scope of the subject matter claimed. Therefore, this specification is intended to cover modifications and changes of the various embodiments described herein, provided that these modifications and changes fall within the scope of the appended claims and their equivalents.

Claims

1. A method of removing heat from an electric machine located in a gas turbine engine, the electric machine being located at least partially radially inboard of a core gas flow path, the electric machine comprising an outer generator stator and an inner generator rotor, characterized in that: The method comprises: directing a cooling airflow radially inwardly through an airflow passage extending radially through a strut of a turbine aft frame to an outer casing at least partially defined by a heat shield at least partially surrounding the electric machine; and The cooling airflow is directed radially inwardly through the outer generator stator and toward the inner generator rotor using a cooling manifold to remove heat from the generator rotor, the inner generator rotor being disposed radially inwardly from the outer generator stator.

2. The method according to claim 1, characterized in that: Further included directing the cooling airflow radially through radially extending channels of the inner generator rotor.

3. The method according to claim 2, characterized in that The inner generator rotor includes a plurality of radially extending channels, and the plurality of radially extending channels direct the cooling airflow radially outward toward a gap between the inner generator rotor and the outer generator stator.

4. The method according to claim 1, characterized in that: Wherein the cooling manifold is mounted to a stationary support structure, the cooling manifold includes an axially extending cooling plate, the axially extending cooling plate is located radially inwardly of the inner generator rotor to define another air flow path, and the method includes axially directing the cooling air flow through the another air flow path.

5. The method according to claim 4, characterized in that Further included using a seal to limit the flow rate of the cooling airflow through the other airflow passageway.

6. The method according to claim 4, characterized in that The flow rate of the cooling air flow through the another air flow passage is restricted using one or more openings through the cooling manifold, the one or more openings having a diameter sized to restrict the cooling air flow.

7. The method according to claim 1, characterized in that The inner generator rotor includes a rotor disk, wherein the rotor disk includes a plurality of surface-mounted permanent magnets and an axially extending cooling duct receiving the cooling airflow.

8. The method according to claim 7, characterized in that The cooling channel extends axially between adjacent permanent magnets.

9. The method according to claim 1, characterized in that: Wherein the inner generator rotor comprises a rotor disk including radially extending channels, the method comprises directing the cooling airflow into a gap between the inner generator rotor and the outer generator stator.

10. The method according to claim 1, characterized in that The cooling manifold comprises a radial portion extending alongside the generator rotor, the radial portion directing the cooling air flow towards the end windings of the outer generator stator and directing spent cooling air into a gap between the inner generator rotor and the outer generator stator.

11. The method according to claim 1, characterized in that: Further included is an accelerator located radially inside the inner generator rotor and coupled to a rotating component, the accelerator moving the cooling airflow in a circumferential direction when the cooling airflow approaches the inner generator rotor.

12. The method according to claim 1, characterized in that Further comprising an axially extending cooling plate located radially inwardly of the inner generator rotor to define another airflow path rotating with the inner generator rotor, the method comprising axially directing the cooling airflow through the another airflow path.

13. A gas turbine engine, characterized in that: include: a compressor section and a turbine section arranged in a serial flow order, the compressor section and the turbine section together defining a core airflow path; a rotating component rotatable with at least a portion of the compressor section and at least a portion of the turbine section; an electric machine located at least partially radially inward of the core airflow path, the electric machine comprising an outer generator stator and an inner generator rotor coupled to the rotating member; a heat shield at least partially forming an enclosure around the electric machine, the heat shield at least partially defining a cooling airflow path at least partially surrounding the electric machine; as well as A cooling manifold directs cooling airflow received from an airflow passage extending radially through a strut of a turbine aft frame through the outer generator stator and to the inner generator rotor, the inner generator rotor being disposed radially inwardly from the outer generator stator.

14. The gas turbine engine according to claim 13, characterized in that Further included is a cooling plate inwardly adjacent the inner generator rotor, the cooling plate having radially extending channels that direct the cooling airflow radially outwardly toward the inner generator rotor.

15. The gas turbine engine according to claim 14, characterized in that The cooling plate includes a plurality of radially extending channels, and the plurality of radially extending channels direct the cooling airflow radially outward toward the inner generator rotor.

16. The gas turbine engine according to claim 15, characterized in that The cooling manifold is mounted to a stationary support structure, the cooling manifold comprising an axially extending portion located radially inwardly of the cooling plate to define another air flow passage, the other air flow passage axially directing the cooling air flow between the cooling plate and the axially extending portion of the cooling manifold.

17. The gas turbine engine according to claim 13, characterized in that wherein the cooling manifold is mounted to a stationary support structure, the cooling manifold comprising an axially extending portion located radially inwardly of the inner generator rotor to define another air flow passage, the other air flow passage axially directing the cooling air flow between the inner generator rotor and the axially extending portion of the cooling manifold.

18. The gas turbine engine according to claim 17, characterized in that Further included is a seal in the another air flow path, the seal thereby limiting the flow rate of the cooling air flow.

19. The gas turbine engine according to claim 13, characterized in that The inner generator rotor includes a rotor disk, wherein the rotor disk includes a plurality of surface-mounted permanent magnets and an axially extending cooling duct receiving the cooling airflow.

20. The gas turbine engine according to claim 19, characterized in that The cooling channel extends axially between adjacent permanent magnets.

21. The gas turbine engine according to claim 13, characterized in that The inner generator rotor comprises a rotor disk, wherein the rotor disk comprises radially extending channels, wherein the radially extending channels guide the cooling airflow to a gap between the inner generator rotor and the outer generator stator.

22. The gas turbine engine according to claim 13, characterized in that The cooling manifold includes a radial portion extending alongside the inner generator rotor and directing the cooling air flow towards the end windings of the outer generator stator and directing spent cooling air into a gap between the inner generator rotor and the outer generator stator.

23. The gas turbine engine according to claim 13, characterized in that Further included is an accelerator located radially inward of the inner generator rotor and coupled to the rotating member, the accelerator being configured to move the cooling airflow in a circumferential direction when the cooling airflow approaches the inner generator rotor.

24. The gas turbine engine according to claim 13, characterized in that The struts include a thermal insulation layer surrounding and along the airflow passageway, the airflow passageway extending radially through the struts.

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