Patent Publication Number: US-2022235671-A1

Title: Embedded electric machine

Description:
FIELD OF THE DISCLOSURE 
     The present subject matter relates generally to a gas turbine engine having an embedded electric machine. 
     BACKGROUND OF THE DISCLOSURE 
     Typical aircraft propulsion systems include one or more gas turbine engines. For certain propulsion systems, the gas turbine engines generally include a fan and a core arranged in flow communication with one another. Additionally, the core of the gas turbine engine general includes, in serial flow order, a compressor section, a combustion section, a turbine section, and an exhaust section. In operation, air is provided from the fan to an inlet of the compressor section where one or more axial compressors progressively compress the air until it reaches the combustion section. Fuel is mixed with the compressed air and burned within the combustion section to provide combustion gases. The combustion gases are routed from the combustion section to the turbine section. The flow of combustion gasses through the turbine section drives the turbine section and is then routed through the exhaust section, e.g., to atmosphere. 
     For certain aircraft, it may be beneficial for the propulsion system to include an electric fan to supplement propulsive power provided by the one or more gas turbine engines included with the propulsion system. However, providing the aircraft with a sufficient amount of energy storage devices to power the electric fan may be space and weight prohibitive. Notably, certain gas turbine engines may include auxiliary generators positioned, e.g., within a cowling of the gas turbine engine. However, these auxiliary generators may not be configured to provide a sufficient amount of electrical power to adequately drive the electric fan. 
     Accordingly, a propulsion system for an aircraft having one or more gas turbine engines and electric generators capable of providing an electric propulsor with a desired amount of electrical power would be useful. 
     BRIEF DESCRIPTION OF THE DISCLOSURE 
     Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     In one exemplary embodiment of the present disclosure, a gas turbine engine is provided defining a radial direction and an axial direction. The gas turbine engine includes: a compressor section and a turbine section arranged in serial flow order, the compressor section and turbine section together defining a working air flowpath; a rotary component rotatable with at least a portion of the compressor section and with at least a portion of the turbine section; an electrical system comprising an electric machine coupled to the rotary component at least partially inward of the working air flowpath along the radial direction and an electric bus electrically coupled to the electric machine, the electric bus including an electric line extending through the working air flowpath within or downstream of the turbine section; and a cooling system including a cooling fluid supply line and a cooling fluid return line, wherein a portion of the electric line extending though the working air flowpath is substantially embedded within the cooling fluid supply line, and wherein a portion of the cooling fluid supply line extending though the working air flowpath is substantially embedded within the cooling fluid return line. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  is a top view of an aircraft according to various exemplary embodiments of the present disclosure. 
         FIG. 2  is a port side view of the exemplary aircraft of  FIG. 1   
         FIG. 3  is a schematic, cross-sectional view of a gas turbine engine in accordance with an exemplary aspect of the present disclosure. 
         FIG. 4  is a schematic, cross-sectional view of an electric machine embedded in a gas turbine engine in accordance with an exemplary embodiment of the present disclosure. 
         FIG. 5  is a close-up, schematic, cross-sectional view an electric line embedded in a cooling fluid supply line and a cooling fluid return line according to various exemplary embodiments of the present disclosure. 
         FIG. 6  is a schematic, cross-sectional view of the electric line embedded in the cooling fluid supply line and the cooling fluid return line of  FIG. 5 , along line  6 - 6  of  FIG. 5 . 
         FIG. 7  is a close-up, schematic, cross-sectional view of an electric machine in accordance with an exemplary embodiment of the present disclosure. 
         FIG. 8  is a schematic, cross-sectional view of an electric machine embedded in a gas turbine engine in accordance with another exemplary embodiment of the present disclosure. 
         FIG. 9  is a schematic, cross-sectional view of an electric machine embedded in a gas turbine engine in accordance with yet another exemplary embodiment of the present disclosure. 
         FIG. 10  is a schematic view of a plurality of electric lines embedded in a cooling fluid supply line and a cooling fluid return line according to various exemplary embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. 
     The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations. Additionally, unless specifically identified otherwise, all embodiments described herein should be considered exemplary. 
     As used herein, the terms “first”, “second”, and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. 
     The terms “forward” and “aft” refer to relative positions within a gas turbine engine or vehicle, and refer to the normal operational attitude of the gas turbine engine or vehicle. For example, with regard to a gas turbine engine, forward refers to a position closer to an engine inlet and aft refers to a position closer to an engine nozzle or exhaust. 
     The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows. 
     The terms “coupled,” “fixed,” “attached to,” and the like refer to both direct coupling, fixing, or attaching, as well as indirect coupling, fixing, or attaching through one or more intermediate components or features, unless otherwise specified herein. 
     The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. 
     Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a 1, 2, 4, 10, 15, or 20 percent margin. These approximating margins may apply to a single value, either or both endpoints defining numerical ranges, and/or the margin for ranges between endpoints. 
     Here and throughout the specification and claims, range limitations are combined and interchanged, such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. 
     The present disclosure is generally related to a gas turbine engine of a propulsion system for an aircraft having an electric machine embedded therein. In at least certain embodiments, the gas turbine engine includes a compressor section and a turbine section arranged in serial flow order and together defining a working air flowpath. A rotary component, such as a shaft or spool, is rotatable with at least a portion of the compressor section and the turbine section. 
     The propulsion system and/or gas turbine engine additionally includes an electrical system and a cooling system. The electrical system includes an electric machine embedded within the gas turbine engine and an electric bus. For example, the electric machine may be rotatable with the rotary component and positioned coaxially with the rotary component at least partially inward of the working air flowpath along a radial direction of the gas turbine engine. For example, in at least certain embodiments, the electric machine may be an electric generator, driven by the rotary component. The electric bus includes an electric line extending through the working air flowpath within or downstream of the turbine section. 
     The cooling system is provided to maintain a temperature of the electric machine and electric bus within desired operating temperature ranges, despite their respective locations within a hot section of the engine. In particular, the cooling system includes a cooling fluid supply line and a cooling fluid return line. A portion of the electric line extending though the working air flowpath is substantially embedded within the cooling fluid supply line, and a portion of the cooling fluid supply line extending though the working air flowpath is substantially embedded within the cooling fluid return line. In such a manner, the electric line extending through the working air flowpath is very well shielded from the hot gasses flowing through the turbine section of the engine, and further, a flow of relatively cool cooling fluid through the cooling fluid supply line is also shielded from the hot gasses flowing through the turbine section of the engine. 
     The relatively cool cooling fluid through the cooling fluid supply line may be used to cool the embedded electric machine and optionally other components located within the hot section of the engine (e.g., sumps, bearings, etc.). 
     A gas turbine engine according to such a configuration may allow for inclusion of an embedded electric machine capable of generating high amounts of electrical power, and transferring such electrical power at high voltages through the working air flowpath with a reduced risk of substantial losses and, e.g., corona discharge losses. 
     Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures,  FIG. 1  provides a top view of an exemplary aircraft  10  as may incorporate various embodiments of the present invention.  FIG. 2  provides a port side view of the aircraft  10  as illustrated in  FIG. 1 . As shown in  FIGS. 1 and 2  collectively, the aircraft  10  defines a longitudinal centerline  14  that extends therethrough, a vertical direction V, a lateral direction L, a forward end  16 , and an aft end  18 . 
     Moreover, the aircraft  10  includes a fuselage  12 , extending longitudinally from the forward end  16  of the aircraft  10  towards the aft end  18  of the aircraft  10 , and a pair of wings  20 . As used herein, the term “fuselage” generally includes all of the body of the aircraft  10 , such as an empennage of the aircraft  10 . The first of such wings  20  extends laterally outwardly with respect to the longitudinal centerline  14  from a port side  22  of the fuselage  12  and the second of such wings  20  extends laterally outwardly with respect to the longitudinal centerline  14  from a starboard side  24  of the fuselage  12 . Each of the wings  20  for the exemplary embodiment depicted includes one or more leading edge flaps  26  and one or more trailing edge flaps  28 . The aircraft  10  further includes a vertical stabilizer  30  having a rudder flap  32  for yaw control, and a pair of horizontal stabilizers  34 , each having an elevator flap  36  for pitch control. The fuselage  12  additionally includes an outer surface or skin  38 . It should be appreciated however, that in other exemplary embodiments of the present disclosure, the aircraft  10  may additionally or alternatively include any other suitable configuration of stabilizer that may or may not extend directly along the vertical direction V or horizontal/lateral direction L. 
     The exemplary aircraft  10  of  FIGS. 1 and 2  includes a propulsion system  100 , herein referred to as “system  100 ”. The exemplary system  100  includes one or more aircraft engines and one or more electric propulsion engines. For example, the embodiment depicted includes a plurality of aircraft engines, each configured to be mounted to the aircraft  10 , such as to one of the pair of wings  20 , and an electric propulsion engine. More specifically, for the embodiment depicted, the aircraft engines are configured as gas turbine engines, or rather as turbofan jet engines  102 ,  104  attached to and suspended beneath the wings  20  in an under-wing configuration. Additionally, the electric propulsion engine is configured to be mounted at the aft end of the aircraft  10 , and hence the electric propulsion engine depicted may be referred to as an “aft engine.” Further, the electric propulsion engine depicted is configured to ingest and consume air forming a boundary layer over the fuselage  12  of the aircraft  10 . Accordingly, the exemplary aft engine depicted may be referred to as a boundary layer ingestion (BLI) fan  106 . The BLI fan  106  is mounted to the aircraft  10  at a location aft of the wings  20  and/or the jet engines  102 ,  104 . Specifically, for the embodiment depicted, the BLI fan  106  is fixedly connected to the fuselage  12  at the aft end  18 , such that the BLI fan  106  is incorporated into or blended with a tail section at the aft end  18 , and such that the mean line  15  extends therethrough. It should be appreciated, however, that in other embodiments the electric propulsion engine may be configured in any other suitable manner, and may not necessarily be configured as an aft fan or as a BLI fan. 
     Referring still to the embodiment of  FIGS. 1 and 2 , in certain embodiments the propulsion system further includes one or more electric generators  108  operable with the jet engines  102 ,  104 . For example, one or both of the jet engines  102 ,  104  may be configured to provide mechanical power from a rotating shaft (such as an LP shaft or HP shaft) to the electric generators  108 . Although depicted schematically outside the respective jet engines  102 ,  104 , in certain embodiments, the electric generators  108  may be positioned within a respective jet engine  102 ,  104 . Additionally, the electric generators  108  may be configured to convert the mechanical power to electrical power. For the embodiment depicted, the propulsion system  100  includes an electric generator  108  for each jet engine  102 ,  104 , and also includes a power conditioner  109  and an energy storage device  110 . The electric generators  108  may send electrical power to the power conditioner  109 , which may transform the electrical energy to a proper form and either store the energy in the energy storage device  110  or send the electrical energy to the BLI fan  106 . For the embodiment depicted, the electric generators  108 , power conditioner  109 , energy storage device  110 , and BLI fan  106  are all are connected to an electric bus  111 , such that the electric generator  108  may be in electrical communication with the BLI fan  106  and/or the energy storage device  110 , and such that the electric generator  108  may provide electrical power to one or both of the energy storage device  110  or the BLI fan  106 . Accordingly, in such an embodiment, the propulsion system  100  may be referred to as a gas-electric propulsion system. 
     It should be appreciated, however, that the aircraft  10  and propulsion system  100  depicted in  FIGS. 1 and 2  is provided by way of example only and that in other exemplary embodiments of the present disclosure, any other suitable aircraft  10  may be provided having a propulsion system  100  configured in any other suitable manner. For example, it should be appreciated that in various other embodiments, the BLI fan  106  may alternatively be positioned at any suitable location proximate the aft end  18  of the aircraft  10 . Further, in still other embodiments the electric propulsion engine may not be positioned at the aft end of the aircraft  10 , and thus may not be configured as an “aft engine.” For example, in other embodiments, the electric propulsion engine may be incorporated into the fuselage of the aircraft  10 , and thus configured as a “podded engine,” or pod-installation engine. Further, in still other embodiments, the electric propulsion engine may be incorporated into a wing of the aircraft  10 , and thus may be configured as a “blended wing engine.” Moreover, in other embodiments, the electric propulsion engine may not be a boundary layer ingestion fan, and instead may be mounted at any suitable location on the aircraft  10  as a freestream ingestion fan (e.g., in an underwing-mounted configuration, in a fuselage-mounted configuration, in a tail-mounted configuration, etc.). Furthermore, in still other embodiments, the propulsion system  100  may not include, e.g., the power conditioner  109  and/or the energy storage device  110 , and instead the generator(s)  108  may be directly connected to an electric propulsor. 
     Referring now to  FIG. 3 , a schematic cross-sectional view of a propulsion engine in accordance with an exemplary embodiment of the present disclosure is provided. In certain exemplary embodiments, the propulsion engine may be configured a high-bypass turbofan jet engine  200 , herein referred to as “turbofan  200 .” Notably, in at least certain embodiments, the jet engines  102 ,  104  may be also configured as high-bypass turbofan jet engines. In various embodiments, the turbofan  200  may be representative of jet engines  102 ,  104 . Alternatively, however, in other embodiments, the turbofan  200  may be incorporated into any other suitable aircraft  10  or propulsion system  100 . 
     As shown in  FIG. 3 , the turbofan  200  defines an axial direction A (extending parallel to a longitudinal centerline  201  provided for reference), a radial direction R, and a circumferential direction C (extending about the axial direction A; not depicted in  FIG. 3 ). In general, the turbofan  200  includes a fan section  202  and a turbomachine  204  disposed downstream from the fan section  202 . 
     The exemplary turbomachine  204  depicted generally includes a substantially tubular outer casing  206  that defines an annular inlet  208 . The outer casing  206  encases, in serial flow relationship, a compressor section including a booster or low pressure (LP) compressor  210  and a high pressure (HP) compressor  212 ; a combustion section  214 ; a turbine section including a high pressure (HP) turbine  216  and a low pressure (LP) turbine  218 ; and a jet exhaust nozzle section  220 . The compressor section, combustion section  214 , and turbine section together define a working air flowpath  221  extending from the annular inlet  208  through the LP compressor  210 , HP compressor  212 , combustion section  214 , HP turbine section  216 , LP turbine section  218  and jet nozzle exhaust section  220 . A high pressure (HP) shaft or spool  222  drivingly connects the HP turbine  216  to the HP compressor  212 . A low pressure (LP) shaft or spool  224  drivingly connects the LP turbine  218  to the LP compressor  210 . 
     For the embodiment depicted, the fan section  202  includes a variable pitch fan  226  having a plurality of fan blades  228  coupled to a disk  230  in a spaced apart manner. As depicted, the fan blades  228  extend outwardly from disk  230  generally along the radial direction R. Each fan blade  228  is rotatable relative to the disk  230  about a pitch axis P by virtue of the fan blades  228  being operatively coupled to a suitable actuation member  232  configured to collectively vary the pitch of the fan blades  228  in unison. The fan blades  228 , disk  230 , and actuation member  232  are together rotatable about the longitudinal axis  12  by LP shaft  224  across a power gear box  234 . The power gear box  234  includes a plurality of gears for stepping down the rotational speed of the LP shaft  224  to a more efficient rotational fan speed. 
     Referring still to the exemplary embodiment of  FIG. 3 , the disk  230  is covered by rotatable front hub  236  aerodynamically contoured to promote an airflow through the plurality of fan blades  228 . Additionally, the exemplary fan section  202  includes an annular fan casing or outer nacelle  238  that circumferentially surrounds the fan  226  and/or at least a portion of the turbomachine  204 . The nacelle  238  is supported relative to the turbomachine  204  by a plurality of circumferentially-spaced outlet guide vanes  240 . A downstream section  242  of the nacelle  238  extends over an outer portion of the turbomachine  204  so as to define a bypass airflow passage  244  therebetween. 
     Although not depicted, the variety of rotatory components of the turbofan engine  10  (e.g., LP shaft  224 , HP shaft  222 , fan  202 ) may be supported by one or more oil lubricated bearings. The turbofan engine  10  depicted includes a lubrication system  245  for providing one or more of the oil lubricated bearings with lubrication oil. Further, the lubrication system  245  may include one or more heat exchangers for transferring heat from the lubrication oil with, e.g., bypass air, bleed air, or fuel. 
     Additionally, the exemplary turbofan  200  depicted includes an electric machine  246  rotatable with the fan  226 . Specifically, for the embodiment depicted, the electric machine  246  is configured as an electric generator co-axially mounted to and rotatable with the LP shaft  224  (the LP shaft  224  also rotating the fan  226  through, for the embodiment depicted, the power gearbox  234 ). As used herein, “co-axially” refers to the axes being aligned. It should be appreciated, however, that in other embodiments, an axis of the electric machine  246  may be offset radially from the axis of the LP shaft  224  and further may be oblique to the axis of the LP shaft  224 , such that the electric machine  246  may be positioned at any suitable location at least partially inward of the working air flowpath  221 . 
     The electric machine  246  includes a rotor  248  and a stator  250 . In certain exemplary embodiments, the rotor  248  and stator  250  of the electric machine  246  are configured in substantially the same manner as the exemplary rotor and stator of the electric machine described below. Notably, when the turbofan engine  200  is integrated into the propulsion system  100  described above with reference to  FIGS. 1 and 2 , the electric generators  108  may be configured in substantially the same manner as the electric machine  246  of  FIG. 3 . 
     It should be also appreciated, however, that the exemplary turbofan engine  200  depicted in  FIG. 3  is provided by way of example only, and that in other exemplary embodiments, the turbofan engine  200  may have any other suitable configuration. For example, in other exemplary embodiments, the turbofan engine  200  may be configured as a turboprop engine, a turbojet engine, a differently configured turbofan engine, or any other suitable gas turbine engine. 
     Referring now to  FIG. 4 , an electric machine  246  embedded within a gas turbine engine  200  in accordance with an exemplary embodiment of the present disclosure is depicted. In certain exemplary embodiments, the electric machine  246  and gas turbine engine  200  depicted in  FIG. 4  may be configured in substantially the same manner as the exemplary electric machine  246  and turbofan engine  200  described above with reference to  FIG. 3 . Accordingly, the same or similar numbers may refer to the same or similar parts. 
     More specifically, the electric machine  246  is coupled to a rotary component of the gas turbine engine  200  at a location at least partially inward of the working air flowpath  221  of the gas turbine engine  200  along the radial direction R. More specifically, still, for the embodiment depicted, the electric machine  246  is embedded within a turbine section of the gas turbine engine  200 , and more specifically still, is coupled to an LP shaft  224  of the gas turbine engine  200 . Additionally, the electric machine  246  is positioned at least partially within or aft of the turbine section along an axial direction A. 
     As is depicted, the electric machine  246  generally includes a rotor  248  and a stator  250 . The rotor  248  is attached directly to the LP shaft  224 , such that the rotor  248  is rotatable with the LP shaft  224 . However, in other embodiments, the rotor  248  may be attached to the LP shaft  224  through one or more rotor connection members. 
     By contrast, the stator  250  is attached to a structural support member  256  via one or more stator connection members  254 . In at least certain exemplary embodiments, the electric machine  246  may be an electric generator, such that the rotor  248  is driven by the LP shaft  224 . With such an embodiment, a rotation of the rotor  248  relative to the stator  250  may generate electrical power, which may be transferred via an electric bus  258 , discussed in greater detail below. 
     It should be appreciated, however, that in other exemplary embodiments, the electric machine  246  may instead have any other suitable configuration. For example, in other embodiments the electric machine  246  may include the rotor  248  located radially outward of the stator  250  (e.g., as an out-running electric machine  246 ). Additionally, in certain embodiments, the electric machine  246  may be operated as an electric motor, or may be operated as both an electric motor and an electric generator. Further, the electric machine  246  may be mounted at any suitable location inward of the working air flowpath  221 , within or aft of the turbine section. For example, still, in other embodiments, the electric machine  246  may be rotatable with a high pressure shaft of the engine (not depicted in  FIG. 4 ). 
     Moreover in certain exemplary embodiments, the electric machine  246  may be configured as a permanent magnet electric machine including a plurality of permanent magnets (not shown). For these embodiments, the stator  250  may include one or more coils of electrically conductive wire (not shown). It should be appreciated, however, that in other embodiments, the electric machine  246  may alternatively be configured as an electromagnetic electric machine, including a plurality of electromagnets and active circuitry, as an induction type electric machine, a switched reluctance type electric machine, as a synchronous AC electric machine, or as any other suitable electric generator or motor. 
     Referring still to the exemplary electric machine  246  of  FIG. 4 , the structural support member  256  may be configured as part of an aft frame assembly that extends from an aft frame strut  260 . The aft strut  260  extends through the working air flowpath  221  of the gas turbine engine  200  and is configured to provide structural support for the gas turbine engine  200 . The structural support member  256 , for the embodiment shown, also extends forward to support an aft engine bearing  262 —the aft engine bearing  262  rotatably supporting an aft end of the LP shaft  224 . 
     The stator connection member  254  may be an annular/cylindrical member extending from the structural support member  256  of the gas turbine engine  200 . For the embodiment depicted, the stator connection member  254  further supports rotation of the LP shaft  224  through one or more bearings. More specifically, the gas turbine engine  200  depicted further includes a forward electric machine bearing  264  is positioned forward of the electric machine  246  and between the LP shaft  224  and the stator connection member  254  along a radial direction R. Similarly, an aft electric machine bearing  266  is positioned aft of the electric machine  246  and between the LP shaft  224  and the stator connection member  254  along the radial direction R. Particularly for the embodiment depicted, the forward electric machine bearing  264  and aft electric machine bearing  266  are each depicted as a roller element bearing. However in other embodiments one or both may alternatively be configured as a ball bearing, or any other suitable bearing. For example, it should be appreciated that the forward and aft electric machine bearings  264 ,  266  may in other embodiments, have any other suitable configuration and the present disclosure is not intended to be limited to the specific configuration depicted, unless such limitations are added to the claims. 
     For the embodiment shown, the gas turbine engine  200  further defines an aft turbine sump  270 . The aft turbine sump  270  is defined, for the embodiment shown, at least in part by the structural support members  256  and Stater connection members  254 . The aft turbine sump  270  encloses at least in part, the aft engine bearing  262  for, e.g., containing a lubrication oil provided to the aft engine bearing  262  through a lubrication oil supply system (not depicted in  FIG. 4 ; discussed below). For the embodiment shown, the aft turbine sump  270  is fluidly bounded by a forward sump seal  276 , as well as by a forward electric machine seal  278 . The forward sump seal  276  and forward electric machine seal  278  may maintain lubrication oil provided to the aft engine bearing  262  substantially within the aft turbine sump  270 . 
     Notably, it will further be appreciated that the embodiment shown, the electric machine  246  is further positioned within an electric machine compartment  280 , which depending on a fluid provided thereto (e.g. a cooling fluid, discussed below), may be referred to as an electric machine sump. The electric machine compartment  280  is defined at least in part by the stator connection member  254  and the forward electric machine seal  278 . Moreover, for the embodiment shown, the gas turbine engine  200  further includes an aft electric machine seal  280 , further defining the electric machine compartment  280 . The forward and aft electric machine seals  278 ,  280  may substantially fluidly contain a fluid within the electric machine compartment  280 . 
     It will be appreciated, however, that in other exemplary embodiments, the arrangement of the bearings  264 ,  266  and seals  278 ,  280  may be reversed, such that the seals  278  and  280  are positioned closer to the electric machine  246  than the bearings  264 ,  266 , respectively. With such a configuration, the seals  278 ,  280  may substantially fluidly isolate the electric machine compartment  280  from, e.g., the aft turbine sump  270 . Such a configuration may be chosen depending on, e.g., a fluid provided thereto (e.g. a cooling fluid, discussed below). 
     As briefly discussed above, during operation of the gas turbine engine  200  the LP shaft  224  may rotate the rotor  248  of the electric machine  246 , allowing electric machine  246  to function as an electric generator producing electrical power. Additionally, the electric machine  246  is in electrical communication with—i.e. electrically connected to—the electric bus  258 . The electric bus  258  may generally include a plurality of electric lines, various power electronic and converts, represented schematically as  282 , etc. The electric bus  258  may electrically connect the electric machine  246  with other aircraft power sources and sinks to exchange power during operation in response to, e.g., an aircraft or engine controller. 
     For the embodiment show, the electric bus  258  is electrically connected to the electric machine  246  at a location radially inward of the working air flowpath  221 . The electric bus  258  includes one or more electric lines, referred to for convenience as a single electric line  284 , extending through the working air flowpath  221  at a location within or aft of the turbine section. More specifically, the electric line  284  includes an intermediate portion  286  extending through the working air flowpath  221 . The electric bus  258  further includes a first junction box  288  located outward of the working air flowpath  221  along the radial direction R and a second junction box  290  located inward of the working air flowpath  221  along the radial direction R. The intermediate portion  286  extends from the first junction box  288  to the second junction box  290 , through the working air flowpath  221 . 
     The exemplary gas turbine engine  200  depicted further includes a cooling system  292  to assist with maintaining a temperature of the intermediate portion  286  of electric bus  258  and the electric machine  246  within a desired operating temperature range during operation of the gas turbine engine  200 . 
     For example, as will be appreciated, each of the plurality of permanent magnets of the electric machine  246 , if included, defines a Curie temperature limit which may be less than a temperature within the working air flowpath  221  extending through the turbine section of the gas turbine engine  200 . The cooling system  292  of the gas turbine engine  200  may function to maintain a temperature of the electric machine  246 , and more particularly each of the permanent magnets, below the Curie temperature limit for the plurality of permanent magnets. Further, the cooling system  292  may maintain a temperature of the electric machine  246  below a predetermined limit of the Curie temperature limit to, e.g., increase a useful life of the electric machine  246 . For example, in certain exemplary embodiments, the cooling system  292  the gas turbine engine  200  may maintain a temperature of the electric machine  246  below at least about a 50 degrees Fahrenheit (° F.) limit of the Curie temperature limit, such as below at least about a 75° F. limit or 100° F. limit of the Curie temperature limit. Maintaining a temperature of the electric machine  246  below such a limit of the Curie temperature limit may further prevent any permanent magnets of the electric machine  246  from experiencing un-recoverable (or permanent) de-magnetization, which may have a negative life impact on the electric machine  246 . 
     Moreover, during operation of a gas turbine engine  200  including an electric machine  246  in accordance with an exemplary embodiment of the present disclosure, the electric machine  246  may be configured to generate a relatively high amount of electric power, such as alternating current electric power. For example, in certain embodiments, the electric machine  246  may be configured to generate and deliver through the electric lines  284  of the electric bus  258  electrical power at five hundred (500) Volts (“V”) or more. For example, in certain embodiments, the electric machine  246  may be configured to generate and deliver through the electric lines  284  of the electric bus  258  electrical power at six hundred (600) V or more. Such a configuration may be enabled by the disclosed cooling system  292   284  for maintaining a temperature of the electric machine  246  within a certain operating temperature range, and/or by designing the intermediate portion  286  of the electric bus  258  in a manner allowing it to be traverse the relatively high temperatures within the working air flowpath  221  downstream of the combustion section of the gas turbine engine  200 , while carrying the relatively high voltages. 
     Referring specifically to the embodiment shown, the cooling system  292  includes a cooling fluid supply line  294  and a cooling fluid return line  296 . A portion of the electric bus  258  extending through the working air flowpath  221 , e.g., the intermediate portion  286  of the electric line  284 , is substantially embedded within the cooling fluid supply line  294 , and further a portion of the cooling fluid supply line  294  extending through the working air flowpath  221  is substantially embedded within the cooling fluid return line  296 . 
     More specifically, for the embodiment depicted in  FIG. 4 , all of the portion of the electric line  284  extending through the working air flowpath  221  is embedded within the cooling fluid supply line  294 , and similarly, all of the portion of the cooling fluid supply line  294  extending through the working air flowpath  221  is embedded within the cooling fluid return line  296 . 
     In such a manner, it will be appreciated that the electric line  284  is surrounded by a flow of cooling fluid  298  through the cooling fluid supply line  294 , such that the intermediate portion  286  of the electric bus  258  traversing the working air flowpath  221  is not exposed directly to anything outside of the cooling fluid supply line  294 . Similarly, for the embodiment shown, the cooling fluid supply line  294  is surrounded by a flow of cooling fluid  298  returning through the cooling fluid return line  296 , such that cooling fluid supply line  294  traversing the working air flowpath  221  is not exposed directly to anything outside of the cooling fluid return line  296 . 
     For example, referring briefly to  FIGS. 5 and 6 , close-up, cross-sectional views of the cooling fluid supply line  294 , the cooling fluid return line  296 , and the intermediate portion  286  of the electric bus  258  are shown. In particular,  FIG. 5  provides a close-up, schematic, cross-sectional view of this assembly along a lengthwise direction of this assembly, and  FIG. 6  provides a close-up, schematic, cross-sectional view of this assembly along the crosswise direction of the assembly (along Line  6 - 6  in  FIG. 5 ). 
     In such a manner, the portion of the electric bus  258  extending through the working air flowpath  221  is very well insulated from the relatively high temperatures within the working air flowpath  221 , such that the electric line  284  may carry the desired amount of electric power through the working air flowpath  221  and remain within temperature limits for the materials. Further, a flow of cooling fluid  298  through the cooling fluid supply line  294  is also insulated from the relatively high temperatures within the working air flowpath  221 , such that the flow of cooling fluid  298  through the cooling fluid supply line  294  may cool, e.g., the electric machine  246 , as will be described in more detail below. 
     More specifically, as noted above, the exemplary cooling system  292  includes the first junction box  288  located outward of the working air flowpath  221  along the radial direction R and the second junction box  290  located inward of the working air flowpath  221  along the radial direction R. The intermediate portion  286  of the electric bus  258  extends from the first junction box  288  to the second junction box  290 . At the first junction box  288 , the electric line  284  of the electric bus  258  is provided into an interior of the cooling fluid supply line  294 , and the cooling fluid supply line  294  is provided to an interior of the cooling fluid return line  296 . This embedded arrangement extends to the second junction box  290 , where the cooling fluid return line  296  splits off and fluidly connects with the electric machine compartment  280 . The cooling fluid return line  296  may scavenge cooling fluid within the electric machine compartment  280 , for returning the cooling fluid to a location outward of the working air flowpath  221 , as described below. 
     Also at the second junction box  290 , the cooling fluid supply line  294  extends to the electric machine  246 , with electric line  284  of the electric bus  258  still embedded therein. For example, referring now to  FIG. 7 , providing a close-up, schematic view of the electric machine  246 , as well as a close-up, schematic view of a portion of the electric bus  258  and the cooling system  292 . For the embodiment shown, the cooling fluid supply line  294  is in fluid communication with an electric machine heat exchanger  300 , the electric machine  246 , or both for cooling the electric machine  246 . More specifically, for the exemplary embodiment depicted, the electric machine  246  includes an electric machine heat exchanger  300  thermally coupled to the stator  250  or of the electric machine  246 , and further includes an electric machine juncture box  302  for receiving the cooling fluid supply line  294  with an electric line  284  of the electric bus  258  position therein. The electric machine juncture box  302  separates the electric line  284  from the interior of the cooling fluid supply line  294 . The electric line  284  electrically couples to the stator  250 , and a flow of cooling fluid  298  through the cooling fluid supply line  294  is provided to the electric machine heat exchanger  300 . In the embodiment shown, the electric machine heat exchanger  300  includes a plurality of passages  304  that circumferentially surround at least a portion of the stator  250  (extending in a circumferential direction C). The flow of cooling fluid  298  from the cooling fluid supply line  294  flows through these passages  304  to reduce a temperature of the stator  250 , and in turn of the electric machine  246 . 
     For the embodiment shown, the electric machine heat exchanger  300  includes an inlet  306  for receiving the flow of cooling fluid  298  from the electric machine juncture box  302  and an outlet  308 . In the embodiment shown, the outlet  308  provides the flow of cooling fluid  298  direction to the electric machine compartment  280 , to be scavenged by the cooling system return line  296 . 
     Additionally, or alternatively, in other exemplary embodiments, the outlet  308  of the electric machine heat exchanger  300  may be directly fluidly coupled to the cooling fluid return line  296 , as is depicted in phantom in  FIG. 7 . 
     In one or more of these configurations, the flow of cooling fluid  298  may further act as a lubricant and/or heat exchange fluid for the forward electric machine bearing  264  and the aft electric machine bearing  266  (see  FIG. 4 ). In such manner, it will be appreciated that in certain exemplary embodiments, the flow of cooling fluid  298  may be a flow of a liquid cooling fluid, such as a flow of a lubricating oil. 
     However, in other exemplary embodiments, the cooling fluid may additionally or alternatively be a gaseous cooling fluid, such as air. With such a configuration, the air may not act as a lubricant for any bearings. However, such may allow for the cooling system  292  to cool the electric machine  246  without needing additional structures or protections for the electric machine  246  for guiding the flow of the cooling fluid. For example, such a configuration, the flow of cooling fluid  298  from the cooling fluid supply line  294  may simply be directed over one or more aspects of the electric machine  246  to cool the electric machine  246 . 
     Referring still to  FIG. 4 , in the embodiment shown, the cooling system  292  is a closed loop cooling system  292 . For example, in the embodiment shown, the cooling fluid supply line  294  and the cooling fluid return line  296  are in series flow communication. For example, during typical operations, a flow of cooling fluid  298  is provided through the cooling fluid supply line  294  to the first junction box  288 . Within the first junction box  288 , as noted above, the cooling fluid supply line  294  is routed to a conduit embedded within the cooling fluid return line  296  extending through the working air flowpath  221 . A relatively cool flow of cooling fluid  298  is then separated at the second junction box  290  to a portion of the cooling fluid supply line  294  extending to the electric machine  246 . The relatively cool flow of cooling fluid  298  is then used to remove heat from the electric machine  246 , reducing a temperature of electric machine  246 . After having accepted heat from the electric machine  246 , the relatively warm cooling fluid is provided to the cooling fluid return line  296  and to the second junction box  290 . At the second junction box  290 , the relatively warm cooling fluid is provided to a portion of the cooling fluid return line  296  surrounding a portion of the cooling fluid return line  296  and extending through the working air flowpath  221  (shielding the relatively cool flow of cooling fluid  298  within the cooling fluid supply line  294  from the high temperatures of the working air flowpath  221 ) to the first junction box  288 . At the first junction box  288 , the relatively warm cooling fluid is separated out to a separate cooling fluid return line  296 . For the embodiment shown, a coo configured to receive the relatively warm cooling fluid from the cooling fluid return line  296 , cool the relatively warm cooling fluid back down to a relatively cool cooling fluid, and provide the relatively cool cooling fluid to the cooling fluid supply line  294 . The closed-loop flow may then repeat. 
     In certain exemplary embodiments, the cooling system  292  further includes a cooling portion  310 . The cooling portion  310  of the cooling system  292  may be, e.g., a heat exchanger for reducing a temperature of the cooling fluid. For example, the heat exchanger may be a surface cooler configured to utilize a flow of air over the cowling  206  of the turbomachine, an air-oil cooler heat exchanger, an oil-oil cooler heat exchanger, a heat exchanger integrated with a thermal bus, etc. 
     It will be appreciated, however, than in other exemplary embodiments, the cooling system  292  may have any other suitable configuration. For example, referring now to  FIG. 8 , a schematic view of a gas turbine engine  200  having an electrical system and a cooling system  292  in accordance with another exemplary embodiment of the present disclosure is provided. The exemplary gas turbine engine  200 , electrical system, and cooling system  292  depicted in  FIG. 8  may be configured in a similar manner as the exemplary gas turbine engine  200 , electrical system, and cooling system  292  described above with reference to  FIGS. 4 through 7 . 
     For example the exemplary gas turbine engine  200  depicted includes an electrical system having electric machine  246  embedded within a turbine section of the gas turbine engine  200  and an electrical bus electrically coupled to the electric machine  246  and having an electric line  284  extending through a working air flowpath  221  of the gas turbine engine  200  within or downstream of the turbine section. In addition, the exemplary gas turbine engine  200  includes a cooling cooling fluid supply line  294  in a cooling fluid return line  296  where a portion of the electric machine  246  extending to the air flowpath is essentially embedded within the cooling fluid supply line  294  and a portion of the cooling fluid supply line  294  extending to the working air flowpath  221  is substantially embedded within the cooling fluid return line  296 . 
     Further, for the embodiment shown, the exemplary cooling system  292  further includes a cooling portion  310 , the cooling portion  310  including a heat exchanger  312 . In certain exemplary embodiments, the heat exchanger  312  may be an air-cooled heat exchanger, using an airflow over the cowl  206  of the turbomachine, as is depicted schematically in  FIG. 8 . 
     However, for the embodiment shown, the cooling system  292  further includes an expansion device located downstream of the portion of the cooling fluid return line  296  extending through the working air flowpath  221  and upstream of the cooling portion  310 , or rather upstream of the heat exchanger  312 . For the embodiment shown, the expansion device is a turbine  314 , and the gas turbine engine  200  further includes an auxiliary electric machine  316  driven by the turbine  314 . In such a manner, the cooling system  292  may capture heat from, e.g., the electric machine  246 , and utilize such heat to generate further power. The expanded cooling fluid from the turbine  314  may be provided to the heat exchanger  312 , where a temperature may be further reduced. In such a manner, the cooling system  292  may operate generally according to a Rankine cycle, wherein the hot components inward of the working air flowpath  221  operate to provide the heat and work into the cycle. The turbine  314  and heat exchanger  312  may operate to reduce a temperature of the working fluid. 
     With such a configuration, it will be appreciated that the cooling fluid may be a single phase cooling fluid, such as a liquid (e.g., a lubrication oil), a supercritical fluid (e.g., a supercritical CO2), etc. Additionally or alternatively, the cooling fluid may be a phase change fluid configured to change between gas and liquid phases based on the cycle of the cooling system  292 . In one or more of these configurations, the cooling system  292  may additionally include a compressor, may not include the auxiliary electric machine  316 , etc. 
     Further, in still other exemplary embodiments, any other suitable configuration may be provided for the gas turbine engine  200 , the electrical system, and/or the cooling system  292 . For example, referring now to  FIG. 9 , a gas turbine engine  200 , an electrical system, and a cooling system  292  in accordance with another exemplary embodiment of the present disclosure is provided. The exemplary embodiment of  FIG. 9  may be configured in a similar manner as one or more of the exemplary embodiments described above with reference to  FIGS. 3 through 8 . 
     As will further be appreciated from the embodiment depicted in  FIG. 9 , the gas turbine engine  200  may further include a lubrication oil system  318  for providing a flow of lubrication oil to, e.g., the aft engine bearing  262  within the aft turbine sump  270 . For the embodiment shown, the cooling system  292  is integrated with the lubrication oil system  318 , such that the flow of cooling fluid  298  through the cooling system  292  has the dual function of acting as a cooling fluid for the electric machine  246  and as a lubrication oil/cooling oil for the lubrication oil system  318 . In particular, for the embodiment shown, the cooling system  292  includes a cooling system heat exchanger  312  and the lubrication oil system  318  includes a lubrication oil tank  320 . For the embodiment shown, the cooling system heat exchanger  312  is thermally coupled to the lubrication oil tank  320 . In such a manner, the cooling system heat exchanger  312  may operate to reduce a temperature of the lubrication oil tank  320  and/or the lubrication oil within the lubrication oil tank  320  (which operates as the cooling fluid for the cooling system  292 ). 
     Referring still to  FIG. 9 , for the embodiment shown, the cooling fluid supply line  294  is configured to provide a flow of cooling fluid  298  to both the electric machine  246  and one or more bearings and/or sumps, and the cooling fluid return line  296  is configured to both return a flow of cooling fluid  298  from the electric machine  246  and from one or more bearings and/or sumps (e.g., operate as a lubrication oil scavenge line). More particularly, for the embodiment shown the cooling fluid supply line  294  is configured to provide the flow of cooling fluid  298  to the electric machine  246  and to the aft turbine sump  270 , and the cooling fluid return line  296  is configured to both scavenge cooling fluid  298  from the electric machine and from the aft turbine sump  270 . 
     More particularly, for the embodiment of  FIG. 9 , the cooling system  292  further includes a third junction box, which for the embodiment show is configured as an intermediate junction box  322  located inward of the working air flowpath  221  along the radial direction R, and between the first and second junction boxes  288 ,  290 . The cooling system  292  further includes a first supply branch  324  of the cooling fluid supply line  294  and a first return branch  326  of the cooling fluid return line  296 , each of which fluidly coupled to the intermediate junction box  322 . At the intermediate junction box  322 , the first supply branch  324  of the cooling fluid supply line  294  receives a flow of relatively cool cooling fluid from the cooling fluid supply line  294 . The first supply branch  324  of the cooling fluid supply line  294  is further in fluid communication with the aft turbine sump  270  for providing the relatively cool cooling fluid to the aft turbine sump  270 . Similarly, at the intermediate junction box  322  the first return branch  326  of the cooling fluid return line  296  is fluidly coupled to the cooling fluid return line  296  flowing back to the lubrication oil tank. The first return branch  326  of the cooling fluid return line  296  is further fluidly coupled to the aft turbine sump  270  for scavenging relatively hot cooling fluid from the aft turbine sump  270 , and returning the relatively hot cooling fluid to the lubrication oil tank  320  via the cooling fluid return line  296 . 
     It will be appreciated, however, than in still other exemplary embodiments, the cooling system  292  and electric bus  258  may have any other suitable configuration. For example, referring now to  FIG. 10 , a schematic view of a gas turbine engine  200  having an electrical system and a cooling system  292  in accordance with another exemplary embodiment of the present disclosure is provided. The exemplary gas turbine engine  200 , electrical system, and cooling system  292  depicted in  FIG. 10  may be configured in a similar manner as one or more of the exemplary gas turbine engine  200 , electrical system, and cooling systems  292  described above with reference to  FIGS. 4 through 9 . 
     However, for the exemplary embodiment of  FIG. 10 , the electric bus  258  of the electric system includes a first electric line  284 - 1  and a second electric line  284 - 2  extending through the turbomachinery flowpath  221  to the electric machine  246 . The first and second electric lines  284 - 1 ,  284 - 2  may be a positive and a negative electric line, or any other suitable configuration of electric lines. 
     Further, for the exemplary embodiment depicted in  FIG. 10 , the cooling system  292  includes a cooling fluid supply line  294  and a cooling fluid return line  296 . However, for the embodiment shown, the portion of the cooling fluid supply line  294  extending through the turbomachinery flowpath  221  is not nested within the cooling fluid return line  296 . Instead, for the embodiment depicted, the cooling fluid supply line  294  extends through the turbomachinery flowpath  221  within a first strut  260 - 1  and the cooling fluid return line  296  extends through the turbomachinery flowpath  221  within a second strut  260 - 2 . Moreover, a portion of the first electric line  284 - 1  extending through the turbomachinery flowpath  221  is nested within the cooling fluid supply line  294 , and similarly a portion of the second electric line  284 - 2  extending through the turbomachinery flowpath  221  is nested within the cooling fluid return line  296 . In such a manner, the first and second electric lines  284 - 1 ,  284 - 2  are each shielded from the relatively high temperatures within the turbomachinery flowpath  221  within or downstream of the turbine section of the gas turbine engine  200 . Further, with such a configuration, the assembly of cooling fluid supply and return lines  294 ,  296  and electric lines  284 - 1 ,  284 - 2  may extend through a smaller cross-sectional space (e.g., through smaller struts  260 ), allowing for smaller struts with less interference (e.g., drag) on an airflow through the turbomachinery flowpath  221 . 
     It will be appreciated that although the embodiment of  FIG. 10  shows a single cooling fluid supply line  294  and a single cooling fluid return line  296 , the cooling system may include multiple of these lines, spaced along any suitable number of struts  260  other vanes. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 
     Further aspects and advantages may be derived from one or more configurations of the present disclosure in the clauses below: 
     A gas turbine engine defining a radial direction and an axial direction, the gas turbine engine comprising: a compressor section and a turbine section arranged in serial flow order, the compressor section and turbine section together defining a working air flowpath; a rotary component rotatable with at least a portion of the compressor section and with at least a portion of the turbine section; an electrical system comprising an electric machine coupled to the rotary component at least partially inward of the working air flowpath along the radial direction and an electric bus electrically coupled to the electric machine, the electric bus including an electric line extending through the working air flowpath within or downstream of the turbine section; and a cooling system comprising a cooling fluid supply line and a cooling fluid return line, wherein a portion of the electric line extending though the working air flowpath is substantially embedded within the cooling fluid supply line, and wherein a portion of the cooling fluid supply line extending though the working air flowpath is substantially embedded within the cooling fluid return line. 
     The gas turbine engine of one or more of these clauses, wherein all of the portion of the electric line extending though the working air flowpath is embedded within the cooling fluid supply line. 
     The gas turbine engine of one or more of these clauses, wherein all of the portion of the cooling fluid supply line extending though the working air flowpath is embedded within the cooling fluid return line. 
     The gas turbine engine of one or more of these clauses, wherein the cooling fluid supply line is in fluid communication with an electric machine heat exchanger, the electric machine, or both for cooling the electric machine. 
     The gas turbine engine of one or more of these clauses, wherein the cooling system is a closed loop cooling system. 
     The gas turbine engine of one or more of these clauses, wherein the cooling fluid supply line and the cooling fluid return line are in series flow communication. 
     The gas turbine engine of one or more of these clauses, wherein the cooling system further comprises an expansion device located downstream of the portion of the cooling fluid return line extending through the working air flowpath and a cooling portion located downstream of the expansion device. 
     The gas turbine engine of one or more of these clauses, wherein the expansion device is a turbine, and wherein the gas turbine engine further comprises an auxiliary electric machine driven by the turbine. 
     The gas turbine engine of one or more of these clauses, wherein cooling portion comprises a heat exchanger for receiving heat from a cooling fluid flow through the cooling system. 
     The gas turbine engine of one or more of these clauses, wherein the cooling system is integrated with a lubrication oil system of the gas turbine engine, and wherein the cooling fluid supply line is configured to provide a flow of cooling fluid to the electric machine and to a sump located inward of the working air flowpath. 
     The gas turbine engine of one or more of these clauses, wherein the cooling fluid return line is a lubrication oil scavenge line. 
     The gas turbine engine of one or more of these clauses, wherein the lubrication oil system further comprises a lubrication oil tank, and wherein the cooling system comprises a heat exchanger for cooling a lubrication oil thermally coupled to the lubrication oil tank. 
     The gas turbine engine of one or more of these clauses, wherein the cooling system utilizes a gaseous cooling fluid or a liquid cooling fluid. 
     The gas turbine engine of one or more of these clauses, wherein the cooling system utilizes a phase change cooling fluid. 
     A gas turbine engine defining a radial direction and an axial direction, the gas turbine engine comprising: a compressor section and a turbine section arranged in serial flow order, the compressor section and turbine section together defining a working air flowpath; a rotary component rotatable with at least a portion of the compressor section and with at least a portion of the turbine section; an electrical system comprising an electric machine coupled to the rotary component at least partially inward of the working air flowpath along the radial direction and an electric bus electrically coupled to the electric machine, the electric bus including an electric line extending through the working air flowpath within or downstream of the turbine section; and a cooling system comprising a cooling fluid line, wherein a portion of the electric line extending though the working air flowpath is substantially embedded within the cooling fluid line, and wherein the cooling fluid line extends from a location outward of the working air flowpath along the radial direction to a location inward of the working air flowpath along the radial direction, and wherein the cooling fluid line is in fluid communication with a cavity enclosing the electric machine. 
     The gas turbine engine of one or more of these clauses, wherein the cooling fluid line is a cooling fluid supply line configured to provide a flow of cooling fluid to the cavity enclosing the electric machine. 
     The gas turbine engine of one or more of these clauses, wherein the electric line is a first electric line, wherein the electric bus further comprises a second electric line extending through the working air flowpath within or downstream of the turbine section, wherein the cooling system further comprises a cooling fluid return line, and wherein the second electric line is substantially embedded within the cooling fluid return line. 
     The gas turbine engine of one or more of these clauses, wherein the gas turbine engine comprises a first airfoil and a second airfoil extending through the working gas flowpath withing or downstream of the turbine section and spaced along a circumferential direction of the gas turbine engine, and wherein the cooling fluid supply line extends through the first airfoil and the cooling fluid return line extends through the second airfoil. 
     An accessory system for a gas turbine engine defining a radial direction and comprising a compressor section and a turbine section arranged in serial flow order and a rotary component rotatable with at least a portion of the compressor section and with at least a portion of the turbine section, the compressor section and turbine section together defining a working air flowpath, the accessory system comprising: an electrical system comprising an electric machine and an electric bus, the electric machine configured to be coupled to the rotary component at least partially inward of the working air flowpath along the radial direction, the electric bus electrically coupled to the electric machine and including an electric line configured to extend through the working air flowpath within or downstream of the turbine section; and a cooling system comprising a cooling fluid supply line and a cooling fluid return line, wherein a portion of the electric line configured to extend though the working air flowpath is substantially embedded within the cooling fluid supply line, and wherein a portion of the cooling fluid supply line configured to extend though the working air flowpath is substantially embedded within the cooling fluid return line. 
     The accessory system of one or more of these clauses, wherein the cooling fluid supply line is in fluid communication with an electric machine heat exchanger, the electric machine, or both for cooling the electric machine.