Three-flow gas turbine engine with embedded electric motor

Abstract

A three-flow gas turbine engine with an embedded electric motor and a method of operating the same are disclosed. In one aspect, the three-flow engine includes an electric motor operably coupled to a shaft of the engine. The three-flow engine also includes a core engine and a main fan and an intermediate fan located upstream of the core engine. The main fan, intermediate fan, and low-pressure turbine are operably coupled to the shaft. The three-flow engine defines a ratio of the electric motor length to the low-pressure turbine length. This ratio is equal to or greater than 0.01 and less than or equal to 3.0.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 174,998, filed April 14, 2021, entitled “Three-Stream Gas Turbine Engine with Embedded Motor,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This topic generally relates to gas turbine engines, and more specifically to three-flow gas turbine engines. Background Technology

[0004] A gas turbine engine typically comprises a fan and a core engine arranged in fluid communication with each other. The core of a gas turbine engine typically includes a compressor section, a combustion section, a turbine section, and an exhaust section arranged in a serial flow sequence. During operation, air is supplied from the fan to the 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. These combustion gases are then transported from the combustion section to the turbine section. The flow of combustion gases through the turbine section drives the turbine section and is then transported through the exhaust section, for example, to the atmosphere.

[0005] Some gas turbine engines also include an electric motor operatively coupled thereto to define a hybrid-electric gas turbine engine. This motor can be used to generate electricity. Typically, the electricity generated by the motor is used for the operation of the aircraft and / or engine subsystems. Some motors can also be used to drive rotating components of the engine. However, with the increasing power generation and transmission capabilities of electric motors, there is a need for methods of operating engines that include electric motors to improve overall engine performance and operability.

[0006] Therefore, a gas turbine engine equipped with an electric motor would be useful in addressing one or more of the challenges mentioned above. Summary of the Invention

[0007] Aspects and advantages of the invention will be set forth in part in the description which follows, or may be apparent from the description or may be learned by practice of the invention.

[0008] A three-flow engine and its operating method are provided. In one example aspect, the three-flow engine is architecturally arranged to generate three distinct propulsive thrust flows that collectively provide the engine's net propulsive thrust. The three-flow engine also includes a spool and an electric motor mechanically coupled thereto. In this respect, the three-flow engine is constructed as a hybrid electric motor. The three-flow engine includes a main fan and an intermediate fan. The main fan and the intermediate fan can be coupled to the same spool as the electric motor or to another spool of the engine. Notably, the three-flow gas turbine engine has certain advantageous architectural arrangements and / or defines certain advantageous operating relationships between its components. For example, various tip speed ratios, radius ratios, length ratios, power-to-voltage ratios, and power-to-power ratios can be defined by the three-flow engine.

[0009] These and other features, aspects, and advantages of the invention will be better understood by reference to the following description and the 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. Attached Figure Description

[0010] The complete and effective disclosure of the invention, including its best mode, to those skilled in the art is set forth in the description with reference to the accompanying drawings, wherein:

[0011] Figure 1 Schematic cross-sectional views of a three-flow gas turbine engine according to various embodiments of the present disclosure are provided;

[0012] Figure 2 Provided Figure 1 A close-up schematic cross-sectional view of the front section of a three-flow engine;

[0013] Figure 3 Provides embedding in Figure 1 A schematic cross-sectional view of the electric motor in a three-flow gas turbine engine;

[0014] Figure 4 Provided Figure 1 A schematic cross-sectional view of the rear section of a three-flow gas turbine engine;

[0015] Figure 5 Schematic cross-sectional views of a three-flow gas turbine engine with a ducted main fan according to various embodiments of the present disclosure are provided;

[0016] Figure 6 A schematic cross-sectional view of a three-flow gas turbine engine having an embedded motor located in front of a central fan, according to various embodiments of the present disclosure, is provided;

[0017] Figure 7 Schematic cross-sectional views of a three-flow gas turbine engine according to various embodiments of the present disclosure are provided;

[0018] Figure 8 Provided Figure 7 A close-up schematic cross-sectional view of a three-flow gas turbine engine;

[0019] Figure 9 Schematic cross-sectional views of a three-flow gas turbine engine according to various other embodiments of the present disclosure are provided;

[0020] Figure 10 Schematic cross-sectional views of a three-flow gas turbine engine according to various embodiments of the present disclosure are provided;

[0021] Figure 11A and 11B A flowchart of a method for operating a three-flow engine according to an example embodiment of this disclosure is provided; and

[0022] Figure 12A and 12B A flowchart of a method for operating a three-flow engine according to an example embodiment of the present disclosure is provided. Detailed Implementation

[0023] Reference will now be made in detail to the present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is provided to explain the invention and not to limit it. In fact, it will be apparent to those skilled in the art that modifications and variations can be made to the invention without departing from the scope or spirit of the invention. For example, features shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, the invention is intended to cover these modifications and variations that fall within the scope of any of the claims and their equivalents.

[0024] The detailed description uses numbers and letters to refer to features in the accompanying drawings. The same or similar reference numerals in the drawings and description have been used to refer to the same or similar parts of the invention, and the same numbers denote the same elements throughout the drawings. As used herein, the terms “first,” “second,” and “third” are used interchangeably to distinguish one component from another and are not intended to indicate the position or relative importance of the individual components.

[0025] The terms "upstream" and "downstream" refer to the relative directions of fluid flow within a fluid path. For example, "upstream" refers to the direction from which the fluid flows, and "downstream" refers to the direction in which the fluid flows.

[0026] The terms “connection,” “fixation,” “attachment,” etc., refer to direct connection, fixation, or attachment, as well as indirect connection, fixation, or attachment via one or more intermediate components or features, unless otherwise stated herein.

[0027] The singular forms “a,” “one,” and “the” include plural references unless the context clearly indicates otherwise.

[0028] The approximate language used throughout the specification and claims is applied to modify any quantitative expression that may be altered without changing its associated essential function. Therefore, values ​​modified by one or more terms such as “about,” “approximately,” and “substantially” are not limited to specified exact values. In at least some cases, approximate language may correspond to the precision of the instrument used to measure the value, or the precision of the method or machine used to construct or manufacture the component and / or system. For example, approximate language may refer to a range of 2%, 5%, 10%, or 20%.

[0029] Throughout this specification and claims, scope limitations are combined and interchanged, and unless the context or language otherwise indicates otherwise, such scopes are identified and include all subscopes contained herein. For example, all scopes disclosed herein include endpoints, and endpoints may be combined independently of each other.

[0030] This disclosure relates to a three-flow gas turbine engine equipped with an embedded electric motor and a method of operating the same. The three-flow engine provided herein is architecturally arranged to generate three distinct propulsive thrust flows that collectively provide the engine's net propulsive thrust. It is noteworthy that the inventors of this disclosure have recognized that certain architectural arrangements and / or certain operational relationships between the components of a three-flow gas turbine engine with an embedded electric motor can provide certain advantages over conventional turbofan engines, such as fuel combustion benefits, and other advantages.

[0031] For example, in one example aspect, a three-flow engine and its operating method are disclosed. The three-flow engine includes a motor operatively coupled to a shaft or bob (e.g., a low-pressure shaft) of the engine. Specifically, the motor may include a rotor rotatable with the shaft and a stationary stator. The three-flow engine also includes a core engine and a fan section positioned upstream of a fan section. The fan section includes a main fan and an intermediate fan positioned downstream of the main fan and upstream of the core engine. The main fan and the intermediate fan are operatively coupled to the shaft. In such an embodiment, the architectural arrangement and operating relationship of the components of the three-flow engine can be such that, during operation, the three-flow engine defines a tip speed ratio. The tip speed ratio is defined by the tip speed of the rotor of the motor and the tip speed of the intermediate fan blades of the intermediate fan. In some embodiments, for example, the tip speed ratio is defined as equal to or greater than 0.2 and less than or equal to 1.0. In this respect, the motor and the intermediate fan are architecturally arranged and operated such that the tip speed of the motor is equal to or less than the tip speed of the intermediate fan. As will be explained herein, various other architectural and operating relationships can be defined by the three-flow engine in conjunction with the tip speed ratio.

[0032] Now turn to the attached diagram. Figure 1 A schematic cross-sectional view of a gas turbine engine according to an example embodiment of the present disclosure is provided. In particular, Figure 1 It provides a third-flow turbofan engine for aviation, referred to in this article as "Third-Flow Engine 100". Figure 1 The three-flow engine 100 can be installed on aircraft, such as fixed-wing aircraft, and can generate thrust for propulsion. The three-flow engine 100 is called a "three-flow engine" because its architecture provides three different airflows that generate thrust during operation.

[0033] For reference, the three-flow engine 100 defines an axial direction A, a radial direction R, and a circumferential direction C. Furthermore, the three-flow engine 100 defines an axial centerline or longitudinal axis 112 extending along the axial direction A. Generally, the axial direction A extends parallel to the longitudinal axis 112, the radial direction R extends outward and inward from the longitudinal axis 112 in a direction perpendicular to the axial direction A, and the circumferential direction extends 360° around the longitudinal axis 112. The three-flow engine 100 extends, for example, along the axial direction A between a front end 114 and a rear end 116.

[0034] The three-flow engine 100 includes a core engine 118 and a fan section 150 positioned upstream therefrom. Typically, the core engine 118 includes a compressor section, a combustion section, a turbine section, and an exhaust section in a sequential flow order. Specifically, as... Figure 1 As shown, the core engine 118 includes an engine core 120 and an annular core shroud 122 surrounding the engine core 120. The engine core 120 and core shroud 122 define an annular core inlet 124. The core shroud 122 further surrounds and supports a turbocharger or low-pressure compressor 126 for pressurizing air entering the core engine 118 through the core inlet 124. A high-pressure multistage axial compressor 128 receives pressurized air from the LP compressor 126 and further increases the air pressure. The pressurized air flows downstream to a combustor 130, where fuel is injected into the pressurized air flow and ignited to increase the temperature and energy level of the pressurized air.

[0035] High-energy combustion products flow downstream from combustor 130 to high-pressure turbine 132. High-pressure turbine 132 drives high-pressure compressor 128 via a first shaft or high-pressure shaft 136. In this respect, high-pressure turbine 132 is drivably coupled to high-pressure compressor 128. High-energy combustion products then flow to low-pressure turbine 134. Low-pressure turbine 134 drives low-pressure compressor 126, components of fan section 150, and motor 200 via a second shaft or low-pressure shaft 138. In this respect, low-pressure turbine 134 is drivably coupled to low-pressure compressor 126, components of fan section 150, and motor 200. In this example embodiment, LP shaft 138 is coaxial with HP shaft 136. After driving each of turbines 132, 134, combustion products exit core engine 118 through core exhaust nozzle 140 to generate propulsive thrust. Therefore, core engine 118 defines a core flow path or core conduit 142 extending between core inlet 124 and core exhaust nozzle 140. The core conduit 142 is an annular conduit positioned approximately inside the core cover 122 along the radial direction R.

[0036] Fan section 150 includes the main fan 152. For example... Figure 1 The main fan 152 depicted is an open rotor or ductless main fan 152. However, in other embodiments, the main fan 152 may be, for example, a fan housing 157 circumferentially surrounding the main fan 152. Figure 5 ) or nacelle, but rather a duct type. As depicted, the main fan 152 includes an array of fan blades 154 ( Figure 1 (Only one is shown). Fan blades 154 are, for example, rotatable about longitudinal axis 112. As described above, the main fan 152 is drivenly connected to the low-pressure turbine 134 via LP shaft 138. The main fan 152 can be directly connected to LP shaft 138, for example, in a direct drive configuration. Alternatively, as... Figure 1 As shown, the main fan 152 can be connected to the LP shaft 138 via a reduction gearbox 155, for example in an indirect drive or gear drive configuration.

[0037] Furthermore, the fan blades 154 may be arranged at equal intervals around the longitudinal axis 112. Each blade 154 has a root and a tip, and a span defined between them. Each blade 154 defines a central blade axis 156. In this embodiment, each blade 154 of the main fan 152 may rotate about its respective central blade axis 156, for example, in unison with each other. One or more actuators 158 may be controlled to pitch the blades 154 about their respective central blade axes 156. However, in other embodiments, each blade 154 may be fixed or may not pitch about its central blade axis 156.

[0038] Fan section 150 also includes a fan guide vane array 160, which includes fan guide vanes 162 arranged around a longitudinal axis 112. Figure 1 (Only one is shown). In this embodiment, the fan guide vane 162 cannot rotate about the longitudinal axis 112. Each fan guide vane 162 has a root and a tip, and a span defined between them. The fan guide vane 162 can be as follows: Figure 1 The fan guide vanes 162 are either unshielded or can be shielded, for example, by an annular shroud spaced outwards from the tips of the fan guide vanes 162 along the radial direction R. Each fan guide vane 162 defines a central blade axis 164. In this embodiment, each fan guide vane 162 of the fan guide vane array 160 can rotate about its respective central blade axis 164, for example, in unison with each other. One or more actuators 166 can be controlled to pitch the fan guide vanes 162 about their respective central blade axes 164. However, in other embodiments, each fan guide vane 162 may be fixed or not pitched about its central blade axis 164. The fan guide vanes 162 are mounted to the fan shroud 170.

[0039] The fan shroud 170 annularly surrounds at least a portion of the core shroud 122 and is generally positioned outside the core shroud 122 in the radial direction R. Specifically, a downstream section of the fan shroud 170 extends over the front portion of the core shroud 122 to define a fan flow path or fan duct 172. Incoming air can enter through the fan duct inlet 176 via the fan duct 172 and exit through the fan exhaust nozzle 178 to generate propulsive thrust. The fan duct 172 is an annular duct generally positioned outside the core duct 142 in the radial direction R. The fan shroud 170 and the core shroud 122 are connected together and are supported by a plurality of substantially radially extending, circumferentially spaced struts 174. Figure 1 (Only one support is shown in the image.) Each of the struts 174 may have an aerodynamic profile to guide airflow therefrom. Other struts besides struts 174 may be used to connect to and support the fan shroud 170 and / or the core shroud 122.

[0040] The three-flow engine 100 also defines or includes an inlet duct 180. The inlet duct 180 extends between the engine inlet 182 and the core inlet 124 / fan duct inlet 176. The engine inlet 182 is generally defined at the front end of the fan shroud 170 and positioned along the axial direction A between the main fan 152 and the fan guide vane array 160. The inlet duct 180 is an annular duct positioned along the radial direction R inside the fan shroud 170. Air flowing downstream along the inlet duct 180 is diverted (not necessarily uniformly) into the core duct 142 and the fan duct 172 by the nose of the diffuser 144 of the core shroud 122. The inlet duct 180 is wider than the core duct 142 along the radial direction R. The inlet duct 180 is also wider than the fan duct 172 along the radial direction R.

[0041] Now for reference Figure 1 and 2 , Figure 2 A close-up schematic cross-sectional view of the front portion of the three-flow engine 100 is provided. As depicted, the fan section 150 also includes an intermediate fan 190. The intermediate fan 190 includes intermediate fan blades 192. Figure 1 An array of (only one shown) is used. The intermediate fan blades 192 can, for example, rotate about the longitudinal axis 112. The intermediate fan 190 is drivenly connected to the low-pressure turbine 134 via the LP shaft 138. The intermediate fan blades 192 can be arranged at equal circumferential intervals about the longitudinal axis 112. (As shown in the image) Figure 2 As best shown, each intermediate fan blade 192 has a root 194 and a tip 196, as well as a span defined therebetween. Furthermore, each intermediate fan blade 192 has a leading edge 198 and a trailing edge 199. The intermediate fan blades 192 are annularly surrounded or form ducts by a fan shroud 170. In this respect, the intermediate fan 190 is positioned inside the fan shroud 170 along the radial direction R. Furthermore, for this example embodiment, the intermediate fan 190 is positioned within the inlet duct 180 upstream of the core duct 142 and the fan duct 172.

[0042] Therefore, the air flowing through the inlet duct 180 passes over the intermediate fan blades 192 and is accelerated downstream therefrom, particularly at the tip 196 of the intermediate fan blades 192. At least a portion of the air accelerated by the intermediate fan blades 192 flows into the fan duct 172 and is ultimately discharged through the fan exhaust nozzle 178 to generate thrust. Furthermore, at least a portion of the air accelerated by the intermediate fan blades 192 flows into the core duct 142 and is ultimately discharged through the core exhaust nozzle 140 to generate thrust. Typically, the intermediate fan 190 is a compressor located downstream of the engine inlet 182. The intermediate fan 190 is operable to accelerate airflow into the fan duct 172 or the secondary bypass passage.

[0043] Embodiments of the engines, systems, and methods provided herein produce increased ductless rotor efficiency at or above a threshold power load (i.e., power / area of ​​the rotor airfoil). In some embodiments, the threshold power load is 25 hp / sq ft or greater at cruise altitude. In specific embodiments of the engines, structures, and methods provided herein, a power load between 25 hp / sq ft and 100 hp / sq ft is produced at cruise altitude. Cruise altitude is typically the altitude at which an aircraft is level after climb and before descending to the approach flight phase. In various embodiments, the engine is applied to a vehicle having a cruise altitude of up to approximately 65,000 feet. In some embodiments, the cruise altitude is between approximately 28,000 feet and approximately 45,000 feet. In some embodiments, the cruise altitude is expressed as a flight altitude layer based on sea-level standard atmospheric pressure, where cruise flight conditions are between FL280 and FL650. In another embodiment, cruise flight conditions are between FL280 and FL450. In some other embodiments, the cruising altitude is defined at least based on atmospheric pressure, wherein, based on a sea-level pressure of approximately 14.70 psia and a sea-level temperature of approximately 59 degrees Fahrenheit, the cruising altitude is between approximately 4.85 psia and approximately 0.82 psia. In another embodiment, the cruising altitude is between approximately 4.85 psia and approximately 2.14 psia. It should be understood that, in some embodiments, the pressure-defined range of cruising altitude may be adjusted based on different reference sea-level pressures and / or sea-level temperatures.

[0044] Therefore, it should be understood that this type of engine is designed to generate between approximately 25,000 and 35,000 pounds of thrust during operation at rated speed.

[0045] for Figure 1In an exemplary embodiment, the main fan 152 includes twelve (12) fan blades 154. From a load perspective, such a number of blades allows for a reduction in the span of each blade 154, thereby also reducing the overall diameter of the main fan 152 (e.g., to approximately 12 feet in the exemplary embodiment). That is, in other embodiments, the main fan 152 may have any suitable number of blades and any suitable diameter. In some suitable embodiments, the main fan 152 includes at least eight (8) blades 154. In another suitable embodiment, the main fan 152 may have at least twelve (12) blades 154. In yet another suitable embodiment, the main fan 152 may have at least fifteen (15) blades 154. In yet another suitable embodiment, the main fan 152 may have at least eighteen (18) blades 154. In one or more of these embodiments, the main fan 152 includes twenty-six (26) or fewer blades 154, such as twenty (20) or fewer blades 154. Furthermore, in some exemplary embodiments, the main fan 152 may be defined with a diameter of at least 10 feet, such as at least 11 feet, at least 12 feet, at least 13 feet, at least 15 feet, at least 17 feet, at most 28 feet, at most 26 feet, at most 24 feet, at most 16 feet.

[0046] In various embodiments, it should be understood that the three-flow engine 100 includes a ratio of the number of impeller blades 162 to the number of blades 154 that may be less than, equal to, or greater than 1:1. For example, in some embodiments, the three-flow engine 100 may include a ratio of the number of impeller blades 162 to the number of blades 154 that is between 1:2 and 5:2. This ratio may be adjusted based on a variety of factors, including the size of the impeller blades 162, to ensure that the desired amount of turbulence is removed from the airflow from the main fan 152.

[0047] It should be understood that the various embodiments of the single ductless rotary engine depicted and described herein can allow operation at normal subsonic aircraft cruise altitudes of Mach 0.5 or higher. In some embodiments, engine 100 allows operation of normal aircraft at cruise altitudes between Mach 0.55 and Mach 0.85. In some embodiments, engine 100 allows fan tip speeds (i.e., tip speeds of rotor blades 154) equal to or less than 750 feet per second (fps). As will be further understood from the description herein, the load on the main fan 152 or the rotor blades 154 of the rotor assembly can facilitate such flight speeds.

[0048] Furthermore, the three-flow engine 100 can be arranged to limit the ratio of the main fan radius to the intermediate fan radius. The ratio of the main fan radius to the intermediate fan radius is limited to:

[0049] Main fan radius / intermediate fan radius (ratio 1)

[0050] The main fan radius is measured as the radial length or radius along the radial direction R between the leading edge tip of one of the fan blades 154 of the main fan 152 and the longitudinal axis 112. Specifically, as... Figure 1 As best shown, the main fan radius is measured as radius R7, which spans radially between the longitudinal axis 112 and the leading edge tip of one of the fan blades 154 in the longitudinal direction R. The intermediate fan radius is measured as the radial length or radius spanning radially between the longitudinal axis 112 and the leading edge tip of one of the intermediate fan blades 192 in the intermediate fan 190. In particular, as Figure 2 As shown in the best embodiment, the radius of the intermediate fan is measured as radius R6, which spans along the radial direction R between the longitudinal axis 112 and the leading edge tip of one of the intermediate fan blades 192.

[0051] In some embodiments, the three-flow engine 100 defines the ratio of the main fan radius to the intermediate fan radius as equal to or greater than 2.0 and less than or equal to 6.5. Specifically, in some embodiments, the three-flow engine 100 defines the ratio of the main fan radius to the intermediate fan radius as at least about 2.0. In other embodiments, the three-flow engine 100 defines the ratio of the main fan radius to the intermediate fan radius as at least about 2.5. In still other embodiments, the three-flow engine 100 defines the ratio of the main fan radius to the intermediate fan radius as at least about 3.0. For example, in... Figure 1 In the present invention, the ratio of the main fan radius to the intermediate fan radius is slightly greater than 3.0. In some further embodiments, the three-flow engine 100 limits the ratio of the main fan radius to the intermediate fan radius to at least about 4.0. In still other embodiments, the three-flow engine 100 limits the ratio of the main fan radius to the intermediate fan radius to at least about 6.0. In some other embodiments, the three-flow engine 100 limits the ratio of the main fan radius to the intermediate fan radius to about 6.5. For embodiments mentioned in this paragraph having a specified lower limit for the ratio of the main fan radius to the intermediate fan radius, unless otherwise stated, the upper limit of these mentioned ratios may be as high as 6.5. The inventors of this disclosure have recognized that a three-flow engine having a main fan and an intermediate fan arranged according to the said range / ratio advantageously balances aerodynamic performance and engine efficiency with the mechanical constraints of the main fan and the intermediate fan.

[0052] refer to Figure 1The operation of the three-flow engine 100 can be summarized in the following exemplary manner. During operation, the initial or incoming airflow passes through the fan blades 154 of the main fan 152 and is split into a first airflow and a second airflow. The first airflow bypasses the engine inlet 182 and flows generally along the axial direction A outside the fan shroud 1700 in the radial direction R. The first airflow, accelerated by the main fan blades 154, passes through the fan guide vanes 162 and then continues to flow downstream to generate the main propulsion flow, or first thrust flow S1. The majority of the net thrust generated by the three-flow engine 100 is generated by the first thrust flow S1. The second airflow enters the inlet duct 180 through the annular engine inlet 182.

[0053] The second airflow flowing downstream through inlet duct 180 passes over the intermediate fan blades 192 of intermediate fan 190 and is thus compressed. The second airflow flowing downstream of intermediate fan 190 is split by a splitter 144 located at the front end of core shroud 122. Specifically, a portion of the second airflow flowing downstream of intermediate fan 190 flows into core duct 142 through core inlet 124. This portion of the second airflow flowing into core duct 142 is gradually compressed by LP compressor 126 and HP compressor 128 and finally discharged into the combustion section. The discharged pressurized airflow flows downstream to burner 130, where fuel is introduced to produce combustion gases or products.

[0054] More specifically, burner 130 defines an annular combustion chamber that is substantially coaxial with the longitudinal centerline axis 112. Burner 130 receives an annular flow of pressurized air from HP compressor 128 via a pressure compressor discharge outlet. A portion of this compressor discharge air flows into a mixer (not shown). Fuel is injected by fuel nozzles to mix with air, thereby forming a fuel-air mixture, which is supplied to the combustion chamber for combustion. Ignition of the fuel-air mixture is accomplished by one or more suitable igniters, and the resulting combustion gases flow axially in the direction A towards and into the annular first-stage turbine nozzle of HP turbine 132. The first-stage nozzle is defined by an annular flow passage comprising a plurality of radially extending, circumferentially spaced nozzle blades that deflect the gases so that they flow at an angle and impinge on the first-stage turbine blades of HP turbine 132. Combustion products exit HP turbine 132 and flow through LP turbine 134 and exit core duct 142 through core exhaust nozzle 140 to generate core airflow or second thrust flow S2. In this embodiment, as described above, the HP turbine 132 drives the HP compressor 128 via the HP shaft 136, and the LP turbine 134 drives the LP compressor 126, the main fan 152, the intermediate fan 190, and the motor 200 via the LP shaft 138.

[0055] Another portion of the second airflow flowing downstream of the intermediate fan 190 is diverted by the splitter 144 into the fan duct 172. Air enters the fan duct 172 through the fan duct inlet 176. The air typically flows through the fan duct 172 in the axial direction A and is eventually discharged from the fan duct 172 through the fan exhaust nozzle 178 to generate the third thrust flow S3.

[0056] As used herein, "third flow" or third thrust flow S3 refers to a small fraction of a secondary airflow capable of increasing fluid energy to generate total propulsion system thrust. In some embodiments, the pressure ratio of the third flow is higher than that of the primary propulsion flow (e.g., a bypass or propeller-driven propulsion flow). Thrust can be generated via a dedicated nozzle or by mixing the secondary airflow with the primary propulsion flow or core airflow, such as by mixing it into a common nozzle. In some exemplary embodiments, the operating temperature of the secondary airflow is below the engine's maximum compressor discharge temperature. The operating temperature of the third flow can be less than 350 degrees Fahrenheit (e.g., less than 300 degrees Fahrenheit, less than 250 degrees Fahrenheit, less than 200 degrees Fahrenheit, and at least as high as ambient temperature). In some exemplary embodiments, these operating temperatures can facilitate heat transfer to or from the third flow and separate fluid flows. Furthermore, in some exemplary embodiments, under takeoff conditions, or more specifically, operating at rated takeoff power at sea level, static flight speed, and an ambient temperature of 86 degrees Fahrenheit, the third flow may contribute less than 50% of the total engine thrust (at least, for example, 2% of the total engine thrust). Additionally, in some exemplary embodiments, aspects of the third flow (e.g., airflow, mixing, or exhaust characteristics) and thus the aforementioned exemplary percentage contribution to the total thrust can be passively adjusted during engine operation or purposefully modified using engine control features (e.g., fuel flow rate, motor power, variable stator, variable inlet guide vanes, valves, variable exhaust geometry, or fluid characteristics) to adjust or optimize overall system performance under a wide range of potential operating conditions.

[0057] Despite the third-rate engine 100 already Figure 1 Description and explanation in the text Figure 1 This describes an exemplary three-flow gas turbine engine operable to generate a first thrust flow S1, a second thrust flow S2, and a third thrust flow S3; however, it should be understood that aspects of this disclosure can be applied to engines with three-flow gas turbines having other configurations. For example, in other exemplary embodiments, the main fan 152 may be ducted rather than via a fan housing 157 or an external nacelle, for example, as... Figure 5 As shown. Figure 5 As shown, a bypass passage 159 can be defined between the fan housing 157 and the fan shroud 170. A first thrust flow S1 can flow through the bypass passage 159. One or more circumferentially spaced outlet guide vanes 168 ( Figure 5 (Only one is shown in the image) can extend and connect between the fan housing 157, the fan shroud 170 and the engine core 120 to provide structural support for these components.

[0058] In addition, for Figure 1 The described embodiments (and) Figure 5 In one embodiment, the three-flow engine 100 includes an electric motor operatively coupled to its rotating components. In this respect, the three-flow engine 100 is an aviation hybrid electric propulsion machine. Specifically, as... Figure 1 As shown, the three-flow motor 100 includes a motor 200 operatively coupled to the LP shaft 138. The motor 200 may be directly mechanically coupled to the LP shaft 138, or alternatively, the motor 200 may be mechanically coupled to the LP shaft 138 indirectly, for example, via a gearbox 280. Furthermore, although the motor 200 is operatively coupled to the LP shaft 138 at its rear end, the motor 200 may be coupled to the LP shaft 138 at any suitable location, or may be coupled to other rotating components of the three-flow motor 100, such as the HP shaft 136.

[0059] In some embodiments, motor 200 may be, for example, an electric motor operable to drive or motor-drive LP shaft 138 during engine detonation. In other embodiments, motor 200 may be a generator operable to convert mechanical energy into electrical energy. In this way, the electricity generated by motor 200 can be directed to various engine and / or aircraft systems. In some embodiments, motor 200 may be a dual-function electric motor / generator. Reference will be made below. Figure 3 Further description of motor 200.

[0060] Now for reference Figure 1 and 3 , Figure 3 A close-up schematic diagram of a motor 200 embedded within a three-flow engine 100 is provided. As shown, the motor 200 is embedded in the three-flow engine 100 near its rear end 116. Specifically, the motor 200 is positioned behind the intermediate fan 190 and at least partially overlaps with or is behind the LP turbine 134 along the axial direction A. Furthermore, in this embodiment, the motor 200 is positioned inside the core duct 142 along the radial direction R. As described above, the motor 200 is operatively coupled to the LP shaft 138. It should be understood that in other exemplary embodiments, the motor 200 may be positioned at other suitable locations within the three-flow engine 100. For example, in some embodiments, the motor 200 may be coupled to the LP shaft 138 and positioned axially in front of the intermediate fan 190, for example, as... Figure 6 As shown.

[0061] refer to Figure 3The motor 200 includes a rotor assembly 210 and a stator assembly 220. The motor 200 also defines a centerline 202, which in this example embodiment is aligned with or coaxial with the longitudinal axis 112 of the three-flow engine 100. The rotor assembly 210 includes a rotor connecting member 212 and a rotor 214. Similarly, the stator assembly 220 includes a stator connecting member 222 and a stator 224. The rotor 214 of the rotor assembly 210 and the stator 224 of the stator assembly 220 together define an air gap 230 therebetween. Furthermore, in this embodiment, the rotor 214 includes a plurality of magnets 216, such as a plurality of permanent magnets, and the stator 224 includes a plurality of windings or coils 226. Therefore, the motor 200 can be referred to as a permanent magnet motor. However, in other exemplary embodiments, the motor 200 can be configured in any suitable manner. For example, motor 200 can be configured as an electromagnetic motor, induction motor, switched reluctance motor, synchronous AC motor, asynchronous motor, or any other suitable generator / motor that includes multiple electromagnets and active circuitry.

[0062] In this embodiment, the rotor assembly 210 of the motor 200 is coupled or attached to the LP shaft 138. In this way, the rotor assembly 210 can rotate together with the LP shaft 138. The attachment of the rotor assembly 210 to the LP shaft 138 will be described in more detail below. The stator assembly 220 is coupled or attached to the structural support member 242 of the turbine section. More specifically, the stator connection member 222 extends from the structural support member 242 to the stator 224 to support the stator 224. The structural support member 242 is configured as part of the rear frame assembly 240. The rear frame assembly 240 also includes a rear frame strut 244 extending through the core conduit 142 of the core engine 118. The rear frame strut 244 provides structural support for the three-flow engine 100. The structural support member 242 extends radially R from the inner end of the rear frame strut 244.

[0063] The three-flow engine 100 also includes a cavity wall 250 surrounding at least a portion of the motor 200. More specifically, the cavity wall 250 substantially completely surrounds the motor 200, extending along the axial direction A from a position near the front end of the motor 200 to a position behind the motor 200. The cavity wall 250 can serve as, for example, a cooling air cavity wall, a reservoir for cooling fluid, a protective cover for the motor 200, etc. For example, in some embodiments, the three-flow engine 100 may also include a second cavity wall (not shown) to form a buffer cavity surrounding the motor 200 and to provide thermal protection for the motor 200.

[0064] During certain operations of the three-flow engine 100, the LP shaft 138 rotates the rotor assembly 210 of the motor 200, thereby allowing the motor 200 to generate electricity. Therefore, the motor 200 can operate in generator mode. In some embodiments, in addition to operating in generator mode or alternatively, the motor 200 can operate in drive mode during certain operations of the three-flow engine 100. In drive mode, the rotor assembly 210 of the motor 200 drives the LP shaft 138. The motor 200 is electrically connected to the power bus 260. The power bus 260 is electrically connected to the motor 200 at a location inside the core conduit 142 along the radial direction R. The power bus 260 may extend through the core conduit 142 (e.g., through the rear frame strut 244) and electrically connect the motor 200 to one or more electrical loads (accessory systems, electric / hybrid electric propulsion devices, etc.), power sources (other motors, energy storage units, etc.), or both. Electricity can be supplied to the motor 200 via the power bus 260, for example, when the motor 200 is operating in drive mode, and the electricity generated by the motor 200 can be transmitted or transferred to the power system via the power bus 260, for example, when the motor 200 is operating in generator mode.

[0065] As described above, in this embodiment, rotor assembly 210 is coupled to LP shaft 138. As depicted, rotor connecting member 212 extends between LP shaft 138 and rotor 214 for connecting rotor 214 to LP shaft 138. In the illustrated embodiment, rotor connecting member 212 is connected to LP shaft 138 via a spline connection. More specifically, rotor connecting member 212 includes a connecting portion having a plurality of teeth 218 extending generally along the axial direction A, and similarly, LP shaft 138 includes a connecting portion having a plurality of teeth 139 extending generally along the axial direction A. The plurality of teeth 218 of rotor connecting member 212 are configured to engage with the plurality of teeth 139 of LP shaft 138, thereby securing the two components to each other. In an alternative embodiment, rotor connecting member 212 may be coupled to LP shaft 138 in any other suitable manner. One or more bearings 248 coupled to the extended support member 246 of rear frame assembly 240 may support rotor connecting member 212 relative to LP shaft 138.

[0066] Although motor 200 is already Figure 3 As described and shown in the text, Figure 3 While a specific configuration is available, it should be understood that the inventive aspects of this disclosure can be applied to motors with alternative configurations. For example, stator assembly 220 and / or rotor assembly 210 may have different configurations or may be configured in conjunction with... Figure 3Different arrangements are shown. As an example, in some embodiments, the motor 200 may have a tapered configuration, wherein the rotor 214 and stator 224 may extend longitudinally along the axial direction A at an angle relative to the longitudinal axis 112, for example, such that they are not oriented parallel to the longitudinal axis 112.

[0067] It is worth noting that, in developing the embodiments described above, the inventors of this disclosure discovered that certain operational and geometric relationships between the various components of a three-flow gas turbine engine with an embedded electric motor offer certain advantages over conventional turbofan engines. Furthermore, in conceiving various embodiments of the turbine (including those shown and described above), the inventors discovered certain relationships that, if applied to the turbine, can simplify the selection, integration, or development process of other subsystems residing within the overall architecture, in addition to providing significant advantages inherent in selecting one or more of these relationships for the engine. As an example, for instance in… Figure 1 , 2 The three-flow engine with an embedded motor disclosed in and the other mentioned embodiments provided herein may include components that operate or are arranged geometrically in an advantageous relationship, as explained in more detail below. Ultimately, employing a three-flow engine with an embedded motor as disclosed herein can provide significant fuel combustion advantages over conventional turbofans, as well as other benefits, taking into account the operational, integration, and size limitations of turbines employing this architecture. Furthermore, this disclosure informs those skilled in the art of the impact of this architecture on the overall propulsion system, how relevant systems can be selected as suitable or unsuitable based on the relationships defined herein, where subsystems may be located, and what the operational, environmental, etc., requirements might be.

[0068] Now for reference Figure 1 , 2 As described above, motor 200 and intermediate fan 190 are operatively connected to LP shaft 138. In this respect, both motor 200 and intermediate fan 190 are connected to LP shaft 138 and can operate relative to each other at a tip speed ratio. The tip speed ratio can be constant, particularly during high-efficiency operation, and excludes the possibility of motor 200 being disengaged from LP shaft 138, for example, via a clutch (not shown). The tip speed ratio is defined by the tip speed of the rotor 214 of motor 200 and the tip speed of one of the intermediate fan blades 192 of intermediate fan 190. In other words, the tip speed ratio can be defined as:

[0069] EM tip speed / intermediate fan tip speed (ratio 2)

[0070] The EM tip speed is measured at the outermost point of the rotor 214 of the motor 200, for example at... Figure 3The measurement is taken at position B1 as depicted in the diagram. The outermost point of rotor 214 is defined as the outermost point of rotor 214 relative to the longitudinal axis 112 along the radial direction R. The intermediate fan tip speed is measured at the leading edge tip of one of the intermediate fan blades 192, for example at... Figure 2 The measurement is taken at position A1 as depicted. The tip speed can be measured in any suitable unit of speed, such as meters per second. The same unit of speed will be used for both the EM tip speed and the intermediate fan tip speed when determining the tip speed ratio. In some embodiments, when the three-flow motor 100 is operating, the rotor 214 of the motor 200 has a rotor tip speed equal to or greater than 50 meters per second and less than or equal to 200 meters per second. In yet another embodiment, when the three-flow motor 100 is operating, the rotor 214 of the motor 200 has a rotor tip speed equal to or greater than 140 meters per second and less than or equal to 190 meters per second. This range of rotor tip speeds is particularly suitable for applications such as... Figure 1 , 3 The motor shown in Figure 4 operates and is arranged, for example, in the "tail cone" or rear position. This rotor tip speed range is also particularly suitable for motors such as... Figure 1 , 3 The motor shown in Figure 4 operates and is arranged differently, except that the motor has an external rotor construction instead of... Figure 1 , 3 In addition to the inner rotor configuration shown in Figure 4, the rotor 214 of the motor 200 may have a rotor tip speed equal to or greater than 50 m / s and less than or equal to 200 m / s, as described.

[0071] In some embodiments, the three-flow motor 100 is operated to limit the tip speed ratio to be equal to or greater than 0.2 and less than or equal to 1.0. In this respect, the tip speed of the rotor 214 of the motor 200 is less than or equal to the leading edge tip speed of one of the intermediate fan blades 192 of the intermediate fan 190. The range of tip speed ratios captures the architectural and operational relationship between the intermediate fan 190 of the three-flow motor 100 and the motor 200 (both of which are coupled to the LP shaft 138). The motor tip speed defines the mechanical and operational constraints associated with the motor 200, while the intermediate fan tip speed defines the mechanical and operational constraints associated with the intermediate fan 190. The inventors of this disclosure have recognized that operating the three-flow motor to limit the tip speed ratio within one or more of the aforementioned ranges has certain architectural and operational advantages. For example, operating the three-flow motor within the said range of tip speed ratios can prevent unacceptable losses in power density of the motor 200, can prevent excessive tip speeds of the intermediate fan 190, and can prevent the mechanical performance of the electrical components of the motor 200 from exceeding its limits, among other benefits.

[0072] Still refer to Figures 1 to 3 Also refer to Figure 4 In some embodiments, the three-flow engine 100 may be arranged to define a ratio of intermediate fan radius to motor radius. The ratio of intermediate fan radius to motor radius is defined as follows:

[0073] Intermediate fan radius / EM tip radius (ratio 3)

[0074] The ratio of the intermediate fan radius to the motor radius can be a fixed ratio because both radii can be fixed. The intermediate fan radius is measured as the radial length or radius spanning the longitudinal axis 112 and between the leading edge tip of one of the intermediate fan blades 192 of the intermediate fan 190. Specifically, as... Figure 2 As shown in the optimal configuration, the radius of the intermediate fan is measured as radius R6, which spans along the radial direction R between the longitudinal axis 112 and the leading edge tip of one of the intermediate fan blades 192. Figure 4 As shown in Figure 4, the EM tip radius is measured as the radius R2 spanning the longitudinal axis 112 and the outermost point of the rotor 214 of the motor 200 along the radial direction R.

[0075] In some embodiments, the three-flow motor 100 defines the ratio of the intermediate fan radius to the motor radius as equal to or greater than 1.33 and less than or equal to 3.8. In some further embodiments, the three-flow motor 100 defines the ratio of the intermediate fan radius to the motor radius as equal to or greater than 2.5 and less than or equal to 3.3. In still other embodiments, the three-flow motor 100 defines the ratio of the intermediate fan radius to the motor radius as equal to or greater than 2.9 and less than or equal to 3.2. The range of the intermediate fan radius to motor radius ratio captures the architectural and operational relationship between the motor 200 and the intermediate fan 190 of the three-flow motor 100 (in such an example embodiment, both are coupled to the LP shaft 138).

[0076] In particular, the inventors of this disclosure have recognized that a three-flow motor having a motor and an intermediate fan arranged according to the aforementioned range advantageously balances the aerodynamic and mechanical constraints of the intermediate fan with the motor performance, the mechanical performance of the motor's electrical components, the physical space required by the motor, and the motor's thermal management. For example, according to the aforementioned range of the ratio of the intermediate fan radius to the motor radius, the intermediate fan can be positioned sufficiently far from the longitudinal axis to produce a satisfactory thrust contribution from the third flow, thereby achieving acceptable efficiency, and furthermore, the intermediate fan is positioned sufficiently close to the longitudinal axis so that the impact loss from supersonic tip velocities does not excessively affect performance and the weight of the intermediate fan is acceptable. The aforementioned range allows the intermediate fan to be arranged to achieve these advantages while preventing unacceptable losses to the motor's power density and preventing the mechanical performance of the motor's electrical components from exceeding their limits.

[0077] Still refer to Figures 1 to 4 In some embodiments, the three-flow motor 100 can be arranged to define a ratio of motor length to low-pressure turbine length. This ratio is defined by the axial length of the motor 200 and the axial length of the LP turbine 134. In other words, the motor length to low-pressure turbine length ratio can be defined as follows:

[0078] EM length / LPT length (ratio 4)

[0079] The ratio of motor length to low-pressure turbine length can be a fixed ratio because the axial lengths of motor 200 and LP turbine 134 are fixed. The EM length is measured as the axial length of motor 200. Specifically, refer to... Figure 4 The axial length of motor 200 is defined as the length L2 spanning along the axial direction A between the leading edge and the trailing edge of rotor 214 of motor 200. The LPT length is measured as the axial length of LP turbine 134. More specifically, as... Figure 4 As best shown, the axial length of the LP turbine 134 is defined as the length L1 along the axial direction A between the leading edge of the hub of one turbine blade 133 of the first stage turbine blade 134 and the trailing edge of the hub of one turbine blade 135 of the last stage turbine blade 134. The same unit of length will be used for both the EM length and the LPT length when determining the ratio of the motor length to the low-pressure turbine length.

[0080] In some embodiments, the motor 200 and LP turbine 134 of the three-flow engine 100 define a motor length to low-pressure turbine length ratio equal to or greater than 0.01 and less than or equal to 3.0. In other embodiments, the motor length to low-pressure turbine length ratio is equal to or greater than 0.01 and less than or equal to 0.5, equal to or greater than 0.3 and less than or equal to 1.0, or greater than 1.0 and less than or equal to 3.0, or greater than 2.0 and less than or equal to 3.0. The range of motor length to low-pressure turbine length ratios captures the architectural and operational relationship between the motor 200 and LP turbine 134 of the three-flow engine 100 (in such an example embodiment, both are coupled to the LP shaft 138). More specifically, the inventors of this disclosure have recognized that a three-flow engine having a motor and LP turbine arranged according to the range advantageously balances the weight and load or efficiency considerations of the LP turbine with the space, size, and performance requirements of the motor.

[0081] Still refer to Figures 1 to 4 In some embodiments, the three-flow engine 100 can be arranged to define a ratio of the motor tip radius to the hub radius of the last stage of the low-pressure turbine. This ratio can be defined as follows:

[0082] EM tip radius / LPT last stage blade hub radius (ratio 5)

[0083] The ratio of the motor tip radius to the low-pressure turbine last-stage hub radius can be a fixed ratio because both radii can be fixed. The EM tip radius is measured as the radius R2 along the radial direction R between the outermost point of the rotor 214 of the motor 200 and the longitudinal axis 112. The LPT last-stage blade hub radius is measured as the radial length or radius along the radial direction R between the outermost point of the hub of one of the turbine blades 135 of the last-stage turbine blade of the LP turbine 134 and the longitudinal axis 112. In particular, as Figure 4 As best shown, the hub radius of the last stage blade of the LPT is measured as radius R1, which spans along the radial direction R between the longitudinal axis 112 and the outermost point taken at the trailing edge of the hub 137 of one of the turbine blades in the last stage turbine blade 135 of the LP turbine 134. The outermost point taken at the trailing edge of the hub 137 is the outermost point of the hub 137 relative to the longitudinal axis 112 along the radial direction R.

[0084] In some embodiments, the LP turbine 134 and motor 200 of the three-flow engine 100 define the ratio of the motor tip radius to the hub radius of the last stage of the low-pressure turbine as equal to or greater than 0.1 and less than or equal to 1.0, or equal to or greater than 0.1 and less than or equal to 0.5, or equal to or greater than 0.4 and less than or equal to 1.0, or equal to or greater than 0.7 and less than or equal to 1.0. This range of the ratio of the motor tip radius to the hub radius of the last stage of the low-pressure turbine captures the architectural and operational relationship between the motor 200 and the LP turbine 134 of the three-flow engine 100 (both of which are coupled to the LP shaft 138).

[0085] The inventors of this disclosure have recognized that a three-flow engine having an electric motor and an LP turbine arranged according to the aforementioned range advantageously balances the geometric constraints and operational performance and efficiency of the LP turbine and the electric motor, while also taking into account the thermal constraints associated with the electric motor, particularly for engines with... Figure 1 , 3 The three-flow motor with an embedded motor positioned as shown in Figure 4. Specifically, the inventors have recognized that the architecture having the aforementioned range results in two optimizations. Based on the aforementioned range of the ratio of the motor tip radius to the hub radius of the last stage of the low-pressure turbine, the LP turbine is positioned sufficiently far from the longitudinal axis to provide satisfactory turbine efficiency and physical space for the motor, while not being positioned too far from the longitudinal axis to make motor mounting and encapsulation infeasible. Furthermore, based on the aforementioned range of the ratio of the motor tip radius to the hub radius of the last stage of the low-pressure turbine, the motor is positioned sufficiently far from the longitudinal axis to provide satisfactory motor performance, while also taking into account the thermal constraints associated with the motor.

[0086] Furthermore, as previously described, the intermediate fan 190 and the LP turbine 134 are operatively connected to the LP shaft 138. In this respect, both the intermediate fan 190 and the LP turbine 134 are connected to the LP shaft 138 and are operable to define a ratio of intermediate fan tip speed to low-pressure turbine tip speed. This ratio can be constant, particularly during high-efficiency operation of the three-flow engine 100. The intermediate fan tip speed to low-pressure turbine tip speed ratio is determined by the tip speed of one of the intermediate fan blades 192 of the intermediate fan 190 and the tip speed of the last-stage turbine blade 135 of the LP turbine 134 (see [link to previous description]). Figure 1 and 3 The tip speed of the intermediate fan is limited. In other words, the ratio of the tip speed of the intermediate fan to the tip speed of the low-pressure turbine can be limited as follows:

[0087] Intermediate fan tip speed / LPT tip speed (ratio 6)

[0088] As described above, the tip velocity of the intermediate fan is measured at the leading edge tip of one of the intermediate fan blades 192, for example, in Figure 2 The LPT tip velocity is measured at position A1 depicted in the figure. It is measured at the leading edge tip of one turbine blade in the last stage turbine blade 135 of the LP turbine 134, for example at... Figure 1 The measurement was taken at position C1 as depicted in the figure.

[0089] In some embodiments, the three-flow engine 100 is operated to limit the ratio of the intermediate fan tip speed to the low-pressure turbine tip speed to be equal to or greater than 0.7 and less than or equal to 1.5. In yet another embodiment, the three-flow engine 100 is operated to limit the ratio of the intermediate fan tip speed to the low-pressure turbine tip speed to be equal to or greater than 0.8 and less than or equal to 1.2. In some further embodiments, the three-flow engine 100 is operated to limit the ratio of the intermediate fan tip speed to the low-pressure turbine tip speed to be equal to or greater than 0.9 and less than or equal to 1.1. Such measurements can be taken at the redline speed of the three-flow engine 100 or at any other speed.

[0090] The inventors of this disclosure have recognized certain structural and operational advantages in operating a three-flow engine to limit the ratio of intermediate fan tip speed to low-pressure turbine tip speed within one or more of the aforementioned ranges. Specifically, operating the three-flow engine within the aforementioned range of the intermediate fan tip speed to low-pressure turbine tip speed ratio ensures that the radius of the intermediate fan (i.e., the radial length or radius along the radial direction R across the longitudinal axis and between the leading edge tip of one of the intermediate fan blades) is optimized relative to the low-pressure turbine architecture. For example, when the intermediate fan radius is too large, the tip speed of the intermediate fan may result in unacceptable aerodynamic losses. Furthermore, the mechanical stress on the intermediate fan may become excessive. Conversely, when the intermediate fan radius is too small, the average velocity in the low-pressure turbine blade passages may become too high, which may lead to increased aerodynamic losses. Alternatively, it may be necessary to reduce the hub radius of the intermediate fan blades to accommodate the required flow rate. This could therefore increase the engine length due to duct slope limitations and other encapsulation constraints. The inventors of this disclosure have taken these factors into account in developing the aforementioned range of the intermediate fan tip speed to low-pressure turbine tip speed ratio.

[0091] Furthermore, as described above, the motor 200 and the LP turbine 134 are operatively connected to the LP shaft 138. In this respect, both the motor 200 and the LP turbine 134 are connected to the LP shaft 138 and can be operated to define a low-pressure turbine tip speed to motor tip speed ratio. The low-pressure turbine tip speed to motor tip speed ratio can be constant, especially during high-efficiency operation and excludes the case where the motor 200 is disconnected from the LP shaft 138. The low-pressure turbine tip speed to motor tip speed ratio is determined by the turbine blades 135 of the last stage of the LP turbine 134 (see...). Figure 1 and 3 The tip speed at the leading edge of the turbine is limited by the tip speed of the rotor 214 of the motor 200. In other words, the ratio of the low-pressure turbine tip speed to the motor tip speed can be defined as:

[0092] LPT tip speed / EM tip speed (ratio 7)

[0093] The LPT tip velocity is measured at the leading edge tip of one of the turbine blades 135 in the last stage of the LP turbine 134, for example at... Figure 1 The measurement is taken at position C1 as depicted. The EM tip speed is measured at the outermost point of the rotor 214 of the motor 200, for example at... Figure 3 The measurement is taken at position B1 as depicted in the figure. As previously mentioned, the outermost point of rotor 214 is defined as the outermost point of rotor 214 relative to longitudinal axis 112 along the radial direction R.

[0094] In some embodiments, the three-flow motor 100 is operated to limit the ratio of low-pressure turbine tip speed to motor tip speed to a value equal to or greater than 0.1 and less than or equal to 1.0, equal to or greater than 0.1 and less than or equal to 0.3, or equal to or greater than 0.5 and less than or equal to 0.9. Such measurements can be taken at the redline speed of the three-flow motor 100 or at any other speed, even when the motor 200 is disconnected from the LP shaft 138. The inventors of this disclosure have recognized certain architectural and operational advantages in operating the three-flow motor to limit the low-pressure turbine tip speed to motor tip speed ratio within one or more of the aforementioned ranges. For example, operating the three-flow motor within the aforementioned ranges of the low-pressure turbine tip speed to motor tip speed ratio can prevent unacceptable losses in the power density of the motor, can prevent excessively high low-pressure turbine tip speeds, can prevent the mechanical properties of the electrical components of the motor 200 from exceeding their limits, and other benefits.

[0095] refer to Figures 1 to 4 In some embodiments, the three-flow engine 100 and the embedded electric motor 200 are operated to define a motor power to low-pressure turbine power ratio. When determining the motor power to low-pressure turbine power ratio, the power output of the motor is measured in kW, and the power output of the low-pressure turbine is measured in horsepower (hp), or alternatively, kW / hp.

[0096] EM power / LPT power (ratio 8)

[0097] In some embodiments, the LP turbine 134 and motor 200 of the three-flow engine 100 define the motor power to low-pressure turbine power ratio as equal to or greater than 0.01 and less than or equal to 1.0. In some embodiments, the LP turbine 134 and motor 200 of the three-flow engine 100 may define the motor power to low-pressure turbine power ratio as equal to or greater than 0.01 and less than or equal to 1.0 at flight idle, equal to or greater than 0.01 and less than or equal to 0.2 at flight idle, equal to or greater than 0.1 and less than or equal to 0.45 at flight idle, or equal to or greater than 0.45 and less than or equal to 1.0 at flight idle. As used herein, flight idle refers to the engine speed at a given altitude in flight, where the throttle is set to the minimum or idle position. Based on, for example, ambient air conditions, the engine speed may increase with increasing altitude. The inventors of this disclosure have recognized that a three-flow engine having an electric motor and an LP turbine arranged and operated according to the range advantageously balances the geometric and physical space constraints, thermal requirements, efficiency, and performance of the electric motor and the low-pressure turbine.

[0098] Still refer to Figures 1 to 4In some embodiments, the three-flow motor 100 is operated, and more specifically, the embedded motor 200 is operated to define a power-to-voltage ratio. The power-to-voltage ratio can be constant, particularly during high-efficiency operation and excluding situations where the motor 200 is disconnected from the LP shaft 138. The power-to-voltage ratio is defined by the electrical power output by the motor 200 (in kilowatts) and the voltage level of the motor 200 (in volts of direct current). In other words, the power-to-voltage ratio can be defined as:

[0099] EM power / EM voltage (ratio 9)

[0100] As described above, EM power is measured as the electrical power output by motor 200, in kilowatts (kW). In some embodiments, the electrical power output by motor 200 ranges from 100 kW to 3 megawatts (100 kW - 3 MW). Furthermore, EM voltage is measured as the voltage level of motor 200 (in DC volts, Vdc). In some embodiments, the voltage level of motor 200 ranges from 270 Vdc to 3 kVdc. Therefore, when determining the power-to-voltage ratio, the unit of measurement for power is kW, while the unit of measurement for voltage is Vdc, or in other words, kW / Vdc. Such measurements can be performed at the redline speed of the three-flow motor 100 or any other speed, even when motor 200 is separated from LP shaft 138.

[0101] In some embodiments, the motor 200 operating the three-flow motor 100 is configured to limit the power-to-voltage ratio to be equal to or greater than 0.3 and less than or equal to 2.0. In yet other embodiments, the motor 200 operating the three-flow motor 100 is configured to limit the power-to-voltage ratio to be equal to or greater than 0.35 and less than or equal to 0.5, or equal to or greater than 0.4 and 0.5. This range of power-to-voltage ratios captures the operational relationship between the electrical power and the voltage associated with the motor.

[0102] The inventors of this disclosure have recognized that a three-flow motor having the arrangement shown and described and operating according to the range advantageously balances the physical space required for the motor, the physical space required between the conductive parts of the motor, and partial discharge considerations related to the current level, and thus the increased weight of cables and busbars associated with the motor and / or the aircraft's electrical system. Generally, for higher ratio values, more physical space is available, and the motor is less susceptible to undesirable partial discharges, while higher current levels and therefore higher weight associated with cables and busbars can be expected. Lower ratio values ​​can expect lower current levels and therefore lower weight associated with cables and busbars, while less physical space is available, and the motor is more susceptible to undesirable partial discharges. A power-to-voltage ratio equal to or greater than 0.35 and less than or equal to 0.5 is particularly suitable for applications such as... Figure 1 , 3 The motor is operated and arranged as shown in Figure 4, for example, in the "tail cone" or rear position. However, as described, the power-to-voltage ratio can be equal to or greater than 0.3 and less than or equal to 2.0.

[0103] Still refer to Figures 1 to 4 In some embodiments, the three-flow motor 100 is operated, and more specifically, the embedded motor 200 is operated to define a power-to-AC rated current ratio. This power-to-AC rated current ratio can be constant, particularly during high-efficiency operation and excluding situations where the motor 200 is disconnected from the LP shaft 138. The power-to-AC rated current ratio is defined by the electrical power (in kilowatts) associated with the motor 200 (e.g., the electrical power output by the motor 200) and the motor's AC rated current (in RMS amperes). In other words, the power-to-AC rated current ratio can be defined as:

[0104] EM power / EMAC rated current (ratio 10)

[0105] As previously stated, EM power is measured as the electrical power output by motor 200, in kilowatts (kW). In some embodiments, the electrical power output by motor 200 ranges from 100 kW to 3 megawatts (100 kW - 3 MW). Furthermore, the EM AC rated current is measured as the AC rated current associated with the AC side of motor 200, in ampere-mean-square (RMS) units. Therefore, when determining the power-to-AC rated current ratio, the power is measured in kW, and the voltage is measured in arms, or in other words, kW / arms. Such measurements can be performed at the redline speed of the three-flow motor 100 or at any other speed, even when motor 200 is disconnected from LP shaft 138.

[0106] In some embodiments, the motor 200 operating the three-flow motor 100 is configured to have a power-to-AC rated current ratio equal to or greater than 0.2 and less than or equal to 2.5. In yet other embodiments, the motor 200 operating the three-flow motor 100 is configured to have a power-to-AC rated current ratio equal to or greater than 0.6 and less than or equal to 2.0, or equal to or greater than 0.2 and less than or equal to 1.2, or equal to or greater than 1.8 and less than or equal to 2.5, or equal to or greater than 1.2 and less than or equal to 1.8. These ranges of power-to-AC rated current ratio capture the operational relationship between the electrical power associated with the motor and the AC rated current associated with the motor.

[0107] The inventors of this disclosure have recognized that a three-flow motor having the arrangement shown and described and operating according to the range advantageously balances the physical space required for the motor, the physical space required between the conductive parts of the motor, and partial discharge considerations related to the current level, as well as the thus increased weight of cables and busbars associated with the motor and / or the aircraft's electrical system. Generally, for a lower power-to-AC rated current ratio, more physical space is available, and the motor is less susceptible to undesirable partial discharges, while higher current levels and therefore higher weight associated with cables and busbars can be expected. A higher power-to-AC rated current ratio allows for lower current levels and therefore lower weight associated with cables and busbars, while less physical space is available, and the motor is more susceptible to undesirable partial discharges. A power-to-AC rated current ratio equal to or greater than 0.6 and less than or equal to 2.0 is particularly suitable for applications such as... Figure 1 , 3 The motor is operated and arranged as shown in Figure 4, for example, in the "tail cone" or rear position. However, as described, the power-to-AC rated current ratio can be equal to or greater than 0.2 and less than or equal to 2.5.

[0108] Still refer to Figures 1 to 4 In some embodiments, the three-flow motor 100 is operated, and more specifically, the embedded motor 200 is operated to define a torque-to-AC rated current ratio at maximum speed. This torque-to-AC rated current ratio at maximum speed is defined by the rotor-dependent torque (in Newton-meters) of the motor at its maximum speed and the AC rated current (in RMS amperes) of the motor. In other words, the torque-to-AC rated current ratio at maximum speed can be defined as follows:

[0109] EM torque at maximum speed / EMAC rated current (ratio 11)

[0110] In some embodiments, the motor 200 operating the three-flow engine 100 is configured to limit the torque-to-AC rated current ratio at maximum speed to be equal to or greater than 0.1 and less than or equal to 6.0. In yet another embodiment, the motor 200 operating the three-flow engine 100 is configured to limit the power-to-AC rated current ratio to be equal to or greater than 0.6 and less than or equal to 1.0. The range of torque-to-AC rated current ratios at maximum speed captures the operating relationship between the rotor-related torque and the AC rated current associated with the motor.

[0111] The inventors of this disclosure have recognized that a three-flow motor having the arrangement shown and described, and operating within the range thereof, advantageously balances the torque associated with the motor rotor with the current on the AC side of the motor. A torque-to-AC rated current ratio at maximum speed equal to or greater than 0.6 and less than or equal to 1.0 is particularly suitable for applications such as… Figure 1 , 3 The motor is operated and arranged as shown in Figure 4, for example, in the "tail cone" or rear position. However, as described, the torque-to-AC rated current ratio at maximum speed can be equal to or greater than 0.1 and less than or equal to 6.0.

[0112] In some embodiments, Figures 1 to 4 Third-rate engine 100 and / or Figure 5 and / or Figure 6 The three-flow engine 100 can be configured with a combination of the aforementioned ratios. For example, Figures 1 to 4 The three-flow engine 100 can be arranged and operated to define any suitable combination of ratios 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and 11. Embodiments of the three-flow engine can be arranged and operated to define one of the above ratios or some combination thereof.

[0113] Various examples are provided below. For each example embodiment, the three-flow engine may include a main fan and an intermediate fan. Each example three-flow engine may be arranged to limit the ratio of the main fan radius to the intermediate fan radius to be equal to or greater than 2.0 and less than or equal to 6.5. In some example embodiments, for example, the three-flow engine may be arranged to limit the ratio of the main fan radius to the intermediate fan radius to be at least about 3.0 and less than 4.0.

[0114] Example 1: A three-flow engine with a micro-hybrid configuration has a low-pressure shaft, a main fan operably coupled to the shaft via a gearbox and a connecting fan rotor, an intermediate fan positioned downstream of the main fan and directly operably coupled to the low-pressure shaft, and the intermediate fan having intermediate fan blades. The third flow further includes a low-pressure turbine. The three-flow engine also includes an electric motor operably coupled to the low-pressure shaft. This electric motor is operable to output 350 kW at flight idle. The electric motor has a rotor that rotates with the low-pressure shaft. The three-flow engine is arranged to define a ratio of motor length to low-pressure turbine length. This ratio is defined by the axial length of the electric motor and the axial length of the LP turbine. The motor length is the length along the axial direction defined by the three-flow engine, spanning between the leading edge and trailing edge of the rotor of the electric motor. The low-pressure turbine length is the length along the axial direction, spanning between the leading edge of the hub of one turbine blade in the first stage of the low-pressure turbine and the trailing edge of the hub of one turbine blade in the last stage of the low-pressure turbine. The three-flow engine defines a motor length to low-pressure turbine length ratio of 0.32.

[0115] Example 2: A three-stream engine, as part of a distributed propulsion system, has a low-pressure shaft, a main fan operably coupled to the shaft via a gearbox and a connecting fan rotor, an intermediate fan positioned downstream of the main fan and directly operably coupled to the low-pressure shaft, the intermediate fan having intermediate fan blades. The third stream further includes a low-pressure turbine. The three-stream engine also includes an electric motor operably coupled to the low-pressure shaft. The electric motor has an operable output of 3 MW. The electric motor has a rotor rotatable with the low-pressure shaft. The three-stream engine is arranged to define a ratio of electric motor length to low-pressure turbine length. This ratio is defined by the axial length of the electric motor and the axial length of the LP turbine. The electric motor length is the length along the axial direction defined by the three-stream engine, spanning between the leading edge and trailing edge of the rotor of the electric motor. The low-pressure turbine length is the length along the axial direction, spanning between the leading edge of the hub of one turbine blade in the first stage of the low-pressure turbine and the trailing edge of the hub of one turbine blade in the last stage of the low-pressure turbine. The three-stream engine defines a ratio of electric motor length to low-pressure turbine length of 3.0.

[0116] Example 3: A three-flow engine with a micro-hybrid configuration has a low-pressure shaft, a main fan operably coupled to the shaft via a gearbox and a connecting fan rotor, an intermediate fan positioned downstream of the main fan and directly operably coupled to the low-pressure shaft, the intermediate fan having intermediate fan blades. The third flow further includes a low-pressure turbine. The three-flow engine also includes an electric motor operably coupled to the low-pressure shaft. This electric motor is operably outputting 350 kW at flight idle. The electric motor has a rotor rotatable with the low-pressure shaft. The three-flow engine is arranged to define a ratio of the electric motor tip radius to the low-pressure turbine's last-stage hub radius. The electric motor tip radius spans along a radial direction R defined by the three-flow engine between the engine's longitudinal axis and the outermost point of the electric motor's rotor. The low-pressure turbine's last-stage hub radius spans along a radial direction R between the engine's longitudinal axis and the outermost point of the hub of one of the turbine blades in the last-stage turbine of the low-pressure turbine. The three-flow engine defines the ratio of the electric motor tip radius to the low-pressure turbine's last-stage hub radius as 0.48.

[0117] Example 4: A three-stream engine, as part of a distributed propulsion system, has a low-pressure shaft, a main fan operably coupled to the shaft via a gearbox and a connecting fan rotor, an intermediate fan positioned downstream of the main fan and directly operably coupled to the low-pressure shaft, the intermediate fan having intermediate fan blades. The third stream further includes a low-pressure turbine. The three-stream engine also includes an electric motor operably coupled to the low-pressure shaft. The electric motor is operable to output 3 MW. The electric motor has a rotor rotatable with the low-pressure shaft. The three-stream engine is arranged to define a ratio of the electric motor tip radius to the low-pressure turbine's last-stage hub radius. The electric motor tip radius spans along a radial direction R defined by the three-stream engine between the engine's longitudinal axis and the outermost point of the electric motor's rotor. The low-pressure turbine's last-stage hub radius spans along a radial direction R between the engine's longitudinal axis and the outermost point of the hub of one of the turbine blades in the last-stage turbine of the low-pressure turbine. The three-stream engine defines the ratio of the electric motor tip radius to the low-pressure turbine's last-stage hub radius as 0.48.

[0118] Example 5: A three-flow engine with a micro-hybrid configuration has a low-pressure shaft, a main fan operably coupled to the shaft via a gearbox and a connecting fan rotor, an intermediate fan positioned downstream of the main fan and directly operably coupled to the low-pressure shaft, the intermediate fan having intermediate fan blades. The third flow further includes a low-pressure turbine. The three-flow engine also includes an electric motor operably coupled to the low-pressure shaft. The electric motor has a rotor rotatable with the low-pressure shaft. The three-flow engine is arranged to define a power ratio between the electric motor and the low-pressure turbine. The power output by the electric motor is measured in kilowatts (kW), and the power output by the low-pressure turbine is measured in horsepower (hp). When operating at 37,000 feet, the three-flow engine defines a power ratio between the electric motor and the low-pressure turbine as 0.62.

[0119] Example 6: A three-flow engine with a micro-hybrid configuration has a low-pressure shaft, a main fan operably coupled to the shaft via a gearbox and a connecting fan rotor, an intermediate fan positioned downstream of the main fan and directly operably coupled to the low-pressure shaft, the intermediate fan having intermediate fan blades. The third flow further includes a low-pressure turbine. The three-flow engine also includes an electric motor operably coupled to the low-pressure shaft. The electric motor has a rotor rotatable with the low-pressure shaft. The three-flow engine is arranged to define a power ratio between the electric motor and the low-pressure turbine. The power output by the electric motor is measured in kilowatts (kW), and the power output by the low-pressure turbine is measured in horsepower (hp). When operating at 14,000 feet, the three-flow engine defines a power ratio between the electric motor and the low-pressure turbine as 0.41.

[0120] Example 7: A three-stream engine, as part of a distributed propulsion system, has a low-pressure shaft, a main fan operably coupled to the shaft via a gearbox and a connecting fan rotor, an intermediate fan positioned downstream of the main fan and directly operably coupled to the low-pressure shaft, the intermediate fan having intermediate fan blades. The third stream further includes a low-pressure turbine. The three-stream engine also includes an electric motor operably coupled to the low-pressure shaft. The electric motor has a rotor rotatable with the low-pressure shaft. The electric motor is operable to output 3MW to 15MW, including endpoints. The three-stream engine is arranged to define a power ratio between the electric motor and the low-pressure turbine. The power output by the electric motor is measured in kilowatts (kW), and the power output by the low-pressure turbine is measured in horsepower (hp). During operation, the three-stream engine defines a power ratio between the electric motor and the low-pressure turbine at 0.2.

[0121] Example 8: A three-flow engine has a low-pressure shaft, a main fan operably coupled to the shaft via a gearbox and a fan rotor, an intermediate fan positioned downstream of the main fan and directly operably coupled to the low-pressure shaft, the intermediate fan having intermediate fan blades. The third flow further includes a low-pressure turbine. The three-flow engine also includes an electric motor operably coupled to the low-pressure shaft. The electric motor has a rotor rotatable with the low-pressure shaft. The three-flow engine is arranged to define a ratio of the intermediate fan tip velocity to the low-pressure turbine tip velocity of approximately 1.0.

[0122] Example 9: A three-flow engine has a low-pressure shaft, a main fan operably coupled to the shaft via a gearbox and a connecting fan rotor, an intermediate fan positioned downstream of the main fan and directly operably coupled to the low-pressure shaft, the intermediate fan having intermediate fan blades. The third flow further includes a low-pressure turbine. The three-flow engine also includes an electric motor operably coupled to the low-pressure shaft. The electric motor has a rotor rotatable with the low-pressure shaft. The three-flow engine is arranged and operated such that the ratio of the low-pressure turbine tip speed to the electric motor tip speed is defined as equal to or greater than 0.1 and less than or equal to 1.0. Such a measurement can be taken at the redline speed of the three-flow engine 100 or any other speed, even when the electric motor 200 is disconnected from the low-pressure shaft.

[0123] Now for reference Figure 7 and Figure 8 , Figure 7 A schematic cross-sectional view of another exemplary three-flow engine 100 according to various embodiments of the present disclosure is provided. Figure 8 Provided Figure 7 A close-up schematic cross-sectional view of the three-flow gas turbine engine 100. Figure 7 and 8 The third-rate engine 100 and Figures 1 to 4 The three-flow engine 100 is configured in a similar manner, except as provided below.

[0124] As depicted, in this embodiment, motor 200 is operatively coupled to HP shaft 136. Specifically, in this embodiment, the rotor 214 of motor 200 is directly mechanically coupled to HP shaft 136. Motor 200 is positioned in front of HP compressor 128 but behind intermediate fan 190 along the axial direction A. Furthermore, motor 200 is positioned inside core duct 142 along the radial direction R. Rotor 214 is rotatable relative to stator 224 about its centerline, which in this example embodiment is coaxial with longitudinal axis 112. In this way, it should be understood that motor 200 can generate electricity, for example, when operating in generator mode, or can drive HP shaft 136, for example, when operating in drive mode. In other example embodiments, Figure 7 and Figure 8 The motor 200 of the third-generation engine 100 can be positioned in other suitable locations. For example, in some embodiments, the motor 200 can be positioned within the core cover 122, such as... Figure 9 As depicted. For Figure 9 In one embodiment, the motor 200 is indirectly mechanically connected to the HP shaft 136 via a gearbox 201.

[0125] It is worth noting that the inventors of this disclosure have recognized or otherwise discovered certain operational and geometric relationships among the various components of a three-flow gas turbine engine having an embedded electric motor coupled to a high-pressure shaft or spool, which offers certain advantages compared to conventional turbofan engines. As an example, a three-flow engine having an electric motor operably coupled to the engine's HP shaft, for instance... Figure 7 The embodiments disclosed herein, and those mentioned elsewhere, may include components that operate or are arranged geometrically in an advantageous relationship, ultimately providing significant fuel combustion advantages over conventional turbofans, as well as other benefits.

[0126] like Figure 7 and 8 As shown, the intermediate fan 190 is operatively connected to the LP shaft 138, and the HP turbine 132 is operatively connected to the HP shaft 136. In this respect, the three-flow engine 100 can operate at a ratio of intermediate fan tip speed to high-pressure turbine tip speed. This ratio can be constant. It is defined by the tip speed of one intermediate fan blade 192 of the intermediate fan 190 and the tip speed of one turbine blade 131 of the final stage turbine blade of the HP turbine 132. In other words, the ratio of intermediate fan tip speed to high-pressure turbine tip speed can be defined as:

[0127] Middle fan tip speed / HPT tip speed (ratio 12)

[0128] The tip speed of the intermediate fan is measured at the leading edge tip of one of the intermediate fan blades 192, for example at... Figure 8 The measurement is taken at location A1 depicted in the figure. The HPT tip velocity is measured at the leading edge tip of one of the turbine blades 131 in the last stage of the HP turbine 132, for example at... Figure 8 The measurement is taken at location D1 as depicted in the diagram. For Figure 8 In the depicted embodiment, the last stage turbine blade 131 of the HP turbine 132 is also the first stage, because there is only one stage of high-pressure turbine blade in this example embodiment.

[0129] In some embodiments, the three-flow engine 100 is operated to limit the ratio of the intermediate fan tip speed to the high-pressure turbine tip speed to be equal to or greater than 0.7 and less than or equal to 1.5. In yet another embodiment, the three-flow engine 100 is operated to limit the ratio of the intermediate fan tip speed to the high-pressure turbine tip speed to be equal to or greater than 0.8 and less than or equal to 1.2. In some further embodiments, the three-flow engine 100 is operated to limit the ratio of the intermediate fan tip speed to the high-pressure turbine tip speed to be equal to or greater than 0.9 and less than or equal to 1.1, or about 1.0. Such measurements can be taken at the redline speed of the three-flow engine 100 or at any other speed.

[0130] The inventors of this disclosure have recognized certain architectural and operational advantages in operating a three-flow engine to limit the ratio of intermediate fan tip speed to high-pressure turbine tip speed within one or more of the aforementioned ranges. In particular, operating the three-flow engine within the aforementioned range of the ratio of intermediate fan tip speed to high-pressure turbine tip speed ensures that the radius of the intermediate fan (i.e., the radial length or radius along the radial direction R between the longitudinal axis and the leading edge tip of one of the intermediate fan blades) is optimized relative to the high-pressure turbine architecture. For example, when the intermediate fan radius is too large, the tip speed of the intermediate fan may result in unacceptable aerodynamic losses. Furthermore, the mechanical stress on the intermediate fan may become excessive. Conversely, when the intermediate fan radius is too small, the average velocity in the high-pressure turbine blade passages may become too high, which may lead to increased aerodynamic losses. The inventors of this disclosure have taken these factors into account in developing the aforementioned range of the ratio of intermediate fan tip speed to high-pressure turbine tip speed.

[0131] refer to Figure 7 and Figure 8 In some embodiments, the three-flow engine 100 can be arranged to define a ratio of the intermediate fan hub radius to the motor radius. This ratio can be defined as follows:

[0132] Intermediate fan blade hub radius / EM radius (ratio 13)

[0133] The ratio of the intermediate fan hub radius to the motor radius can be a fixed ratio because both radii can be fixed. The intermediate fan blade hub radius is measured as the radial length or radius along the radial direction R between the outermost point of the hub of one of the intermediate fan blades 192 of the intermediate fan blades 192 of the intermediate fan 190 and the longitudinal axis 112. Specifically, as... Figure 6 and 8As shown in the optimal configuration, the hub radius of the intermediate fan blade is measured as radius R3, which is the outermost point taken along the radial direction R across the longitudinal axis 112 and at the trailing edge of the hub 193 of one of the intermediate fan blades 192 of the intermediate fan 190. The outermost point taken at the trailing edge of the hub 193 is the outermost point of the hub 193 relative to the longitudinal axis 112 along the radial direction R.

[0134] The EM radius is measured as the radius R4 between the outermost point of the rotor 214 or stator 224 (depending on which one is positioned outside the other along the radial direction R) across the longitudinal axis 112. For example, when the rotor 214 is positioned outside the stator 224 along the radial direction R (i.e., when the motor 200 has an outer rotor configuration), the outermost point is considered to be the outermost point of the rotor 214. Conversely, when the stator 224 is positioned outside the rotor 214 along the radial direction R (i.e., when the motor 200 has an outer rotor configuration), the outermost point is considered to be the outermost point of the rotor 214. Figure 6 (When the inner rotor configuration is shown), the outermost point is considered to be the outermost point of the stator 224.

[0135] In some embodiments, the intermediate fan 190 and motor 200 of the three-flow engine 100 define the ratio of the intermediate fan hub radius to the motor radius as equal to or greater than 0.1 and less than or equal to 1.0, equal to or greater than 0.1 and less than or equal to 0.4, equal to or greater than 0.4 and less than or equal to 0.8, or equal to or greater than 0.6 and less than or equal to 1.0. In this way, the outermost point obtained at the trailing edge of the hub 193 is positioned along the radial direction R flush with or outside the outermost point of the rotor 214 or stator 224 of the motor 200 (depending on which one is positioned outside the other along the radial direction R). The inventors of this disclosure have recognized that a three-flow engine having a motor and intermediate fan arranged according to the aforementioned range advantageously balances the geometric constraints of the intermediate fan and motor with operational performance and efficiency, and also takes into account the thermal constraints associated with the motor, particularly for motors with... Figure 7 and 8 The best-positioned embedded motor of the three-flow motor.

[0136] Furthermore, in some embodiments, the three-flow engine 100 can be arranged to define a ratio of the high-pressure compressor impeller hub radius to the motor tip radius. The ratio of the high-pressure compressor hub radius to the motor radius can be defined as follows:

[0137] HPC blade hub radius / EM radius (ratio 14)

[0138] The ratio of the high-pressure compressor hub radius to the motor radius can be a fixed ratio because both radii can be fixed. For example... Figure 8As best shown, the HPC blade hub radius is measured as the radial length or radius R5 between the outermost point taken along the radial direction R across the longitudinal axis 112 and at the leading edge of the hub 129 of one of the first-stage blades 127 of the HP compressor 128. The EM radius is measured as the radius R4 between the outermost point along the radial direction R across the longitudinal axis 112 and the outermost point of the rotor 214 or stator 224 (whichever is positioned outside the other along the radial direction R).

[0139] In some embodiments, the high-pressure compressor 128 of the three-flow engine 100 and the motor 200 define the ratio of the high-pressure compressor hub radius to the motor radius as equal to or greater than 0.1 and less than or equal to 1.0, equal to or greater than 0.1 and less than or equal to 0.25, equal to or greater than 0.25 and less than or equal to 0.5, or equal to or greater than 0.5 and less than or equal to 1.0. In this way, the outermost point obtained at the leading edge of the hub 129 of one of the first-stage blades 127 of the HP compressor 128 is positioned along the radial direction R flush with or outside the outermost point of the rotor 214 or stator 224 of the motor 200 (depending on which one is positioned outside the other along the radial direction R).

[0140] The inventors of this disclosure have recognized that a three-flow motor having an HP-shaft-connected motor and a high-pressure compressor arranged according to the aforementioned range advantageously balances the geometric constraints and operational performance and efficiency of the HP compressor and motor, while also taking into account the thermal constraints associated with the motor, particularly for motors with... Figure 7 and 8 The best-positioned embedded motor of the three-flow motor.

[0141] Still refer to Figure 7 and 8 As described with respect to this embodiment, the HP turbine 132 is operatively connected to the HP shaft 136, and the motor 200 is also operatively connected to the HP shaft 136. In this respect, the three-flow engine 100 can operate at a ratio of high-pressure turbine tip speed to motor tip speed. The ratio of high-pressure turbine tip speed to motor tip speed can be constant, except when the motor 200 is disengaged from the HP shaft 136, for example, via a clutch (not shown). The ratio of high-pressure turbine tip speed to motor tip speed is defined by the tip speed of one turbine blade 131 of the last stage turbine blade of the HP turbine 132 and the tip speed of the rotor 214 of the motor 200. In other words, the ratio of high-pressure turbine tip speed to motor tip speed can be defined as:

[0142] HPT tip speed / EM tip speed (ratio 15)

[0143] HPT tip velocity is measured at the leading edge tip of one turbine blade in the last stage turbine blade 131 of the HP turbine 132, for example in Figure 8 The EM tip speed is measured at position D1 as depicted in the diagram. It is measured at the outermost point of the rotor 214 of the motor 200, for example, at... Figure 8 The measurement is taken at position B2 as depicted in the figure. As previously mentioned, the outermost point of rotor 214 is defined as the outermost point of rotor 214 relative to longitudinal axis 112 along the radial direction R.

[0144] In some embodiments, the three-flow engine 100 is operated to limit the ratio of high-pressure turbine tip speed to motor tip speed to a value equal to or greater than 0.1 and less than or equal to 1.0, equal to or greater than 0.1 and less than or equal to 0.3, equal to or greater than 0.3 and less than or equal to 0.6, or equal to or greater than 0.4 and less than or equal to 1.0. Such measurements can be taken at the redline speed of the three-flow engine 100 or at any other speed. The inventors of this disclosure have recognized certain architectural and operational advantages in operating the three-flow engine to limit the ratio of high-pressure turbine tip speed to motor tip speed within one or more of the aforementioned ranges. For example, operating the three-flow engine within the aforementioned ranges of the high-pressure turbine tip speed to motor tip speed ratio can prevent unacceptable losses in the power density of the motor, can prevent excessively high tips speeds of the high-pressure turbine and high-pressure compressor, and can prevent the mechanical properties of the electrical components of the motor from exceeding their limits, among other benefits.

[0145] In some embodiments, Figure 7 and Figure 8 The three-flow engine 100 depicted can be arranged to define a ratio of high-pressure turbine length to motor length. This ratio is defined by the axial length of the HP turbine 132 and the axial length of the motor 200. In other words, the ratio of high-pressure turbine length to motor length can be defined as follows:

[0146] HPT length / EM length (ratio 16)

[0147] The ratio of high-pressure turbine length to motor length can be a fixed ratio because the axial lengths of the HP turbine 132 and the motor 200 are fixed. The HPT length is measured as the axial length of the HP turbine 132. For example... Figure 8 As best shown, the axial length of the HP turbine 132 is defined as the length L3 along the axial direction A, spanning from the leading edge of one turbine nozzle in the first-stage turbine nozzle 125 of the HP turbine 132 to the trailing edge of one turbine blade in the last-stage turbine blade 131 of the HP turbine 132. The EM length is measured as the axial length of the motor 200. (As shown) Figure 8As shown, the axial length of the motor 200 is defined as the length L4 spanning along the axial direction A between the leading edge and the trailing edge of the rotor 214 of the motor 200.

[0148] In some embodiments, the HP turbine 132 and motor 200 of the three-flow engine 100 define the ratio of high-pressure turbine length to motor length as equal to or greater than 0.1 and less than or equal to 1.5, equal to or greater than 0.1 and less than or equal to 0.5, equal to or greater than 0.5 and less than or equal to 0.85, or equal to or greater than 0.85 and less than or equal to 1.5. This range of high-pressure turbine length to motor length ratios captures the architectural and operational relationship between the motor and the high-pressure turbine (in such example embodiments, both are coupled to a high-pressure shaft) of the three-flow engine. More specifically, the inventors of this disclosure have recognized that a three-flow engine having a motor and high-pressure turbine arranged according to said ranges advantageously balances the weight and load or efficiency considerations of the high-pressure turbine with the performance requirements of the motor.

[0149] Still refer to Figure 7 and Figure 8 In some embodiments, the three-flow motor 100 is operated, more specifically, the embedded motor 200 is operated to define a power-to-voltage ratio, wherein the motor 200 is operatively coupled to the HP shaft 136. The power-to-voltage ratio can be constant, particularly during high-efficiency operation and excluding the case where the motor 200 is disconnected from the HP shaft 136. The power-to-voltage ratio is defined by the electrical power output by the motor 200 (in kilowatts) and the voltage level of the motor 200 (in DC volts). In other words, the power-to-voltage ratio can be defined as:

[0150] EM power / EM voltage (ratio 17)

[0151] As described above, EM power is measured as the electrical power output by motor 200, in kilowatts. In some embodiments, the electrical power output by motor 200 ranges from 100 kilowatts to 1 megawatt (100 kW - 1 MW). Furthermore, EM voltage is measured as the voltage level of motor 200, in direct current volts (Vdc). In some embodiments, the voltage level of motor 200 ranges from 270 Vdc to 3 kVdc.

[0152] In some embodiments, the motor 200 operating the three-flow motor 100 is configured to limit the power-to-voltage ratio to 0.3 or greater and less than or equal to 2.0, 0.3 or greater and less than or equal to 1.1, 0.3 or greater and less than or equal to 0.6, 0.6 or greater and less than or equal to 1.1, or 1.0 or greater and less than or equal to 2.0. Such measurements can be taken at the redline speed of the three-flow motor 100 or at any other speed, even when the motor 200 is disconnected from the LP shaft 138.

[0153] The inventors of this disclosure have recognized that a three-flow motor having the motor arranged as shown and operated according to the range advantageously balances the physical space required for the motor, the physical space required between the conductive parts of the motor, and partial discharge considerations related to the current level, and thus the increased weight of cables and busbars associated with the motor and / or the aircraft's electrical system.

[0154] In some embodiments, Figure 7 and Figure 8 Third-rate engine 100 and / or Figure 9 The three-flow engine can limit the combination of the above ratios. For example, Figure 7 and 8 The three-flow engine 100 can be arranged and operated to define any suitable combination of ratios 1, 12, 13, 14, 15, 16, and 17. Embodiments of the three-flow engine can be arranged and operated to define one of the above ratios or some combination thereof.

[0155] Various examples are provided below. For each example embodiment, the three-flow engine may include a main fan and an intermediate fan. Each example three-flow engine may be arranged to limit the ratio of the main fan radius to the intermediate fan radius to be equal to or greater than 2.0 and less than or equal to 6.5. In some example embodiments, for example, the three-flow engine may be arranged to limit the ratio of the main fan radius to the intermediate fan radius to be at least about 3.0 and less than 4.0.

[0156] Example 10: A three-flow engine has a low-pressure shaft, a main fan operably coupled to the shaft via a gearbox and a connecting fan rotor, an intermediate fan positioned downstream of the main fan and directly operably coupled to the low-pressure shaft, the intermediate fan having intermediate fan blades. The third flow further includes a high-pressure turbine operably coupled to a high-pressure shaft. The three-flow engine also includes an electric motor operably coupled to the high-pressure shaft. The electric motor has a rotor rotatable with the high-pressure shaft. The three-flow engine is arranged to define a ratio of intermediate fan tip velocity to high-pressure turbine tip velocity. The intermediate fan tip velocity is measured at the leading edge tip of one of the intermediate fan blades. The high-pressure tip velocity is measured at the leading edge tip of one of the turbine blades in the final stage of the HP turbine. The three-flow engine defines the ratio of intermediate fan tip velocity to high-pressure turbine tip velocity as 1.0.

[0157] Example 11: A three-flow engine has a low-pressure shaft, a main fan operably connected to the low-pressure shaft via a gearbox and a connecting fan rotor, an intermediate fan positioned downstream of the main fan and directly operably connected to the low-pressure shaft, the intermediate fan having intermediate fan blades. The third flow further includes a high-pressure turbine operably connected to a high-pressure shaft. The three-flow engine also includes an electric motor operably connected to the high-pressure shaft. The electric motor has a rotor rotatable with the high-pressure shaft. The three-flow engine is arranged to define a ratio of high-pressure turbine tip speed to electric motor tip speed. The high-pressure turbine tip speed is measured at the leading edge tip of one of the turbine blades in the last stage of the high-pressure turbine, and the electric motor tip speed is measured at the outermost point of the electric motor's rotor. The three-flow engine defines the ratio of high-pressure turbine tip speed to electric motor tip speed as 0.4.

[0158] Example 12: A three-flow engine has a low-pressure shaft, a main fan operably connected to the low-pressure shaft via a gearbox and a connecting fan rotor, an intermediate fan positioned downstream of the main fan and directly operably connected to the low-pressure shaft, the intermediate fan having intermediate fan blades. The third flow further includes a high-pressure turbine operably connected to a high-pressure shaft. The three-flow engine also includes an electric motor operably connected to the high-pressure shaft. The electric motor has a rotor rotatable with the high-pressure shaft. The three-flow engine is arranged to define a ratio of high-pressure turbine length to electric motor length. The high-pressure turbine length is measured as the axial length of the high-pressure turbine, i.e., the length along the axial direction from the leading edge of one turbine nozzle in the first-stage turbine nozzle of the high-pressure turbine to the trailing edge of one turbine blade in the last-stage turbine blade of the high-pressure turbine. The electric motor length is measured as the axial length of the electric motor. The three-flow engine defines a high-pressure turbine length to electric motor length ratio of 1.3.

[0159] Now for reference Figure 10 , Figure 10A schematic cross-sectional view of a three-flow gas turbine engine 100 according to various embodiments of the present disclosure is provided. Figure 10 The third-rate engine 100 and Figures 1 to 4 , Figure 7 and 8 The configuration is similar to that of the third-rate engine 100, except as provided below.

[0160] In this embodiment, the three-flow gas turbine engine 100 includes a first motor 200A operably coupled to a first shaft or HP shaft 136 and a second motor 200B operably coupled to a second shaft or LP shaft 138. Motors 200A and 200B may be mechanically connected directly or indirectly (e.g., via a gearbox) to their respective shafts 136 and 138. In this example embodiment, the first motor 200A is positioned relative to... Figure 7 and 8 The second motor 200B is positioned at the same location as the first motor 200. Figures 1 to 4 The motors 200A and 200B are located at the same position as motor 200. However, in other embodiments, motors 200A and 200B may be positioned at other suitable locations. In some embodiments, Figure 10 The three-flow engine 100 can limit one or more ratios mentioned in this article.

[0161] It is worth noting that the inventors of this disclosure have recognized that there are certain operational relationships between the various components of a three-flow gas turbine engine having a first embedded motor operably connected to a high-pressure shaft or spool and a second embedded motor operably connected to a low-pressure shaft or spool, which has certain advantages over conventional turbofan engines.

[0162] For example, refer to Figure 10 The three-flow motor 100 can be operated to limit the power ratio of the second motor to the first motor. This power ratio can be constant, especially during high-efficiency operation of the three-flow motor 100 and excluding cases where the first motor 200A is disconnected from the HP shaft 136 and / or the second motor 220B is disconnected from the LP shaft 138. The power ratio is limited by the electrical power output (in kilowatts) of the second motor and the electrical power output (in kilowatts) of the first motor. In other words, the power ratio can be limited as follows:

[0163] Second EM power / First EM power (ratio 18)

[0164] In some embodiments, the three-flow motor 100 is operated to limit the ratio of the second motor power to the first motor power to be equal to or greater than 0.1 and less than or equal to 1.5. In yet other embodiments, the three-flow motor 100 is operated to limit the ratio of the second motor power to the first motor power to be equal to or greater than 0.5 and less than or equal to 1.2, equal to or greater than 0.5 and less than or equal to 0.75, or equal to or greater than 0.75 and less than or equal to 1.2. In some further embodiments, the three-flow motor 100 is operated to limit the ratio of the second motor power to the first motor power to be equal to or greater than 0.6 and less than or equal to 0.9. Such measurements can be taken at the redline speed of the three-flow motor 100 or any other speed. In some embodiments, the electrical power output of the second motor ranges from 100 kW to 3 MW, and the electrical power output of the first motor ranges from 100 kW to 1 MW.

[0165] The inventors of this disclosure have recognized that a three-flow motor having a second motor and a first motor arranged and operated according to the said range advantageously balances the geometric and physical space constraints, thermal requirements, efficiency, and performance of the first and second motors.

[0166] In some embodiments, Figure 10 The three-flow engine 100 can be configured with a combination of the aforementioned ratios. For example, Figure 10 The three-flow engine 100 can be arranged and operated to define any suitable combination of ratios 1 to 18. Embodiments of the three-flow engine can be arranged and operated to define one of the aforementioned ratios or some combination thereof.

[0167] Example 13: A three-flow engine has a low-pressure shaft, a main fan operably connected to the low-pressure shaft via a gearbox and a connecting fan rotor, an intermediate fan positioned downstream of the main fan and directly operably connected to the low-pressure shaft, the intermediate fan having intermediate fan blades. The three-flow engine further includes a first motor mechanically coupled to the low-pressure shaft. The third flow also includes a high-pressure shaft and a second motor mechanically coupled thereto. The three-flow engine is arranged to define a power ratio of the second motor to the first motor. The three-flow engine defines the power ratio of the second motor to the first motor as 0.7.

[0168] Figure 11A and 11B A flowchart of a method (400) for operating a three-flow engine according to an example embodiment of the present disclosure is provided. For example, the method (400) can be used to operate... Figures 1 to 4 , Figure 5 , Figure 6The method (400) is a three-flow gas turbine engine, or any other three-flow engine with an embedded electric motor operatively coupled to a shaft (e.g., a low-pressure shaft) of the engine. It should be understood that the method (400) is discussed herein to describe exemplary aspects of the subject matter and is not intended to be limiting.

[0169] At (402), the method (400) includes operating a three-flow gas turbine engine having an electric motor embedded therein to define one or more ratios, such as those described in (402A) to (402K).

[0170] In some embodiments, the three-flow engine defines a radial direction and has an inlet duct, a core duct in flow communication with the inlet duct, and a fan duct in flow communication with the inlet duct and positioned radially outside the core duct. In such embodiments, an intermediate fan may be positioned within the inlet duct upstream of the core duct and the fan duct. Furthermore, in some embodiments, the three-flow engine has a fan positioned upstream of the intermediate fan and operatively coupled to a shaft (e.g., an LP shaft). In some embodiments, the fan is ductless, for example, as... Figure 1 As shown. In other embodiments, the fan, for example, is via... Figure 5 The external nacelle or fan casing shown is duct-type. Furthermore, in this embodiment, the intermediate fan is positioned between the fan and the low-pressure compressor along the axial direction defined by the three-flow engine. Additionally, in this embodiment, the root of the intermediate fan blades is positioned radially inside the root of the fan blades.

[0171] Furthermore, in some embodiments, the three-flow engine has an engine core and the motor is positioned within the engine core. In this respect, the motor is embedded in the three-flow engine. For example, in some embodiments, the motor may be positioned radially inside the core conduit. Additionally, in some embodiments, the motor is coupled to a shaft (e.g., the LP shaft) behind the intermediate fan, for example, as... Figure 1 As shown. In other embodiments, the motor is coupled to a shaft (e.g., the LP shaft) in front of the intermediate fan. Furthermore, in some embodiments, the motor is directly connected to the shaft. In some alternative embodiments, the motor is indirectly coupled to the shaft, for example, via a gearbox.

[0172] At (402A), method (400) includes operating a three-flow gas turbine engine to define a main fan radius to intermediate fan radius ratio of equal to or greater than 2.0 and less than or equal to 6.5. In such an embodiment, the three-flow gas turbine engine has a main fan having a plurality of fan blades. The main fan radius to intermediate fan radius ratio is defined by the radius between the leading edge tip of one fan blade across the longitudinal axis defined by the three-flow gas turbine engine and the radius across the leading edge tip of one intermediate fan blade. In some other embodiments, the three-flow engine defines a main fan radius to intermediate fan radius ratio of at least about 2.0. In other embodiments, the three-flow engine defines a main fan radius to intermediate fan radius ratio of at least about 2.5. In yet another embodiment, the three-flow engine defines a main fan radius to intermediate fan radius ratio of at least about 3.0. In some further embodiments, the three-flow engine defines a main fan radius to intermediate fan radius ratio of at least about 4.0. In yet another embodiment, the three-flow engine defines a main fan radius to intermediate fan radius ratio of at least about 6.0. In some other implementations, the three-flow engine limits the ratio of the main fan radius to the intermediate fan radius to approximately 6.5.

[0173] At (402B), in addition to or alternatively operating the three-flow gas turbine engine at (402A), the method (400) includes operating the three-flow gas turbine engine to limit the tip speed ratio to be equal to or greater than 0.2 and less than or equal to 1.0, the tip speed ratio being defined by the tip speed of the rotor of the motor and the tip speed of the intermediate fan blades of the intermediate fan. In such an embodiment, both the motor and the intermediate fan are operatively coupled to the shaft of the three-flow gas turbine engine. For example, both the motor and the intermediate fan can be operatively coupled to the low-pressure shaft of the three-flow gas turbine engine.

[0174] At (402C), in addition to operating the three-flow gas turbine engine at (402A) and / or (402B), or alternatively, method (400) includes operating the three-flow gas turbine engine to limit the ratio of the intermediate fan radius to the motor radius to be equal to or greater than 1.33 and less than or equal to 3.8. In some further embodiments, the three-flow engine 100 limits the ratio of the intermediate fan radius to the motor radius to be equal to or greater than 2.5 and less than or equal to 3.3. In yet another embodiment, the three-flow engine 100 limits the ratio of the intermediate fan radius to the motor radius to be equal to or greater than 2.9 and less than or equal to 3.2.

[0175] At (402D), in addition to operating the three-flow gas turbine engine at (402A) and / or at (402B) and / or at (402C), or alternatively, method (400) includes operating the three-flow gas turbine engine to limit the ratio of motor length to low-pressure turbine length to be equal to or greater than 0.01 and less than or equal to 3.0. The range of the motor length to low-pressure turbine length ratio captures the architectural and operational relationship between the motor and the low-pressure turbine. The motor length is the length spanning along the axial direction between the leading and trailing edges of the motor's rotor. The low-pressure turbine length is the length spanning from the leading edge of the hub of one turbine blade in the first stage of the low-pressure turbine to the trailing edge of the hub of one turbine blade in the last stage of the LP turbine.

[0176] At (402E), in addition to operating the three-flow gas turbine engine at (402A) and / or at (402B) and / or at (402C) and / or at (402D), or alternatively, the method (400) includes operating the three-flow gas turbine engine to define the ratio of the motor tip radius to the low-pressure turbine last-stage hub radius as equal to or greater than 0.1 and less than or equal to 1.0. The motor tip radius is the length or radius spanning the longitudinal axis and the outermost point of the motor's rotor. The low-pressure turbine last-stage hub radius is the length or radius spanning the longitudinal axis defined by the three-flow engine and the outermost point taken at the trailing edge of the hub of the last-stage turbine blade of the low-pressure turbine, which is operatively coupled to the shaft.

[0177] At (402F), in addition to or alternatively operating the three-flow gas turbine engine at (402A) and / or at (402B) and / or at (402C) and / or at (402D) and / or at (402E), method (400) includes operating the three-flow gas turbine engine to define the ratio of intermediate fan tip speed to low-pressure turbine tip speed as equal to or greater than 0.7 and less than or equal to 1.5. In such an embodiment, the ratio of intermediate fan tip speed to low-pressure turbine tip speed is defined by the tip speed of the intermediate fan blades of the intermediate fan and the tip speed of the last stage turbine blades of the low-pressure turbine. In some further embodiments, the three-flow gas turbine engine is operated to define the ratio of intermediate fan tip speed to low-pressure turbine tip speed as equal to or greater than 0.8 and less than or equal to 1.2.

[0178] At (402G), in addition to or alternatively operating the three-flow gas turbine engine at (402A) and / or at (402B) and / or at (402C) and / or at (402D) and / or at (402E) and / or at (402F), the method (400) includes operating the three-flow gas turbine engine to limit the ratio of the low-pressure turbine tip speed to the motor tip speed to be equal to or greater than 0.1 and less than or equal to 1.0.

[0179] At (402H), except or alternatively, when operating the three-flow gas turbine engine at (402A) and / or at (402B) and / or at (402C) and / or at (402D) and / or at (402E) and / or at (402F) and / or at (402G), method (400) includes operating the three-flow gas turbine engine to limit the ratio of motor power to low-pressure turbine power to be equal to or greater than 0.01 and less than or equal to 1.0. In determining the ratio of motor power to low-pressure turbine power, the power output by the motor is measured in kW, and the power output by the low-pressure turbine is measured in hp.

[0180] At (402I), in addition to or alternatively operating the three-flow gas turbine engine at (402A) and / or at (402B) and / or at (402C) and / or at (402D) and / or at (402E) and / or at (402F) and / or at (402G) and / or at (402H), method (400) includes operating the three-flow gas turbine engine such that the motor limits the power-to-voltage ratio to be equal to or greater than 0.3 and less than or equal to 2.0. In yet another embodiment, the three-flow gas turbine engine is operated such that the motor limits the power-to-voltage ratio to be equal to or greater than 0.35 and less than or equal to 0.5. The range of the power-to-voltage ratio captures the operational relationship between the electrical power associated with the motor and the voltage associated with the motor. In such embodiments, the power-to-voltage ratio is defined by the electrical power output by the motor (in kilowatts) and the voltage level of the motor (in DC volts). Furthermore, in some embodiments, the electrical output of the motor ranges from 100 kilowatts to 3 megawatts. In addition, in some implementations, the voltage level of the motor ranges between 270 DC volts and 3,000 DC volts.

[0181] At (402J), in addition to or alternatively operating the three-flow gas turbine engine at (402A) and / or at (402B) and / or at (402C) and / or at (402D) and / or at (402E) and / or at (402F) and / or at (402G) and / or at (402H) and / or at (402I), method (400) includes operating the three-flow gas turbine engine such that the motor limits the power-to-AC rated current ratio to be equal to or greater than 0.2 and less than or equal to 2.5. In yet another embodiment, the motor operating the three-flow engine limits the power-to-AC rated current ratio to be equal to or greater than 0.6 and less than or equal to 2.0. The range of power-to-AC rated current ratio captures the operating relationship between the electrical power associated with the motor and the AC rated current associated with the motor.

[0182] At (402K), in addition to operating the three-flow gas turbine engine at (402A) and / or at (402B) and / or at (402C) and / or at (402D) and / or at (402E) and / or at (402F) and / or at (402G) and / or at (402H) and / or at (402I) and / or at (402J), or alternatively, method (400) includes operating the three-flow gas turbine engine such that the motor limits the torque-to-AC rated current ratio at maximum speed to be equal to or greater than 0.1 and less than or equal to 6.0. In yet another embodiment, the motor operating the three-flow engine limits the power-to-AC rated current ratio to be equal to or greater than 0.6 and less than or equal to 1.0. The range of torque-to-AC rated current ratio at maximum speed captures the operating relationship between the rotor-related torque and the AC rated current related to the motor.

[0183] Figure 12A and 12B A flowchart of a method (500) for operating a three-flow engine according to an example embodiment of the present disclosure is provided. For example, the method (500) can be used to operate... Figure 7 and 8 This refers to a three-flow gas turbine engine, or any other three-flow engine with an embedded electric motor operatively coupled to a shaft or spindle (e.g., a high-pressure shaft) of the engine. It should be understood that the method (500) is discussed herein to describe exemplary aspects of the subject matter and is not intended to be limiting. References below... Figure 7 and 8 To provide the content of method (500).

[0184] At (502), the method (500) includes operating a three-flow gas turbine engine having an electric motor embedded therein to define one or more ratios, such as those set forth in (502A) to (502H).

[0185] In some embodiments, the three-flow engine defines a radial direction and has an inlet duct, a core duct in flow communication with the inlet duct, and a fan duct in flow communication with the inlet duct and positioned radially outside the core duct. In such embodiments, an intermediate fan may be positioned within the inlet duct upstream of the core duct and the fan duct. Furthermore, in some embodiments, the three-flow engine has a fan positioned upstream of the intermediate fan and operatively coupled to a second shaft (e.g., an LP shaft). In some embodiments, the fan is ductless, for example, as... Figure 1 As shown. In other embodiments, the fan is ducted, for example, as... Figure 5As shown. Furthermore, in this embodiment, the intermediate fan is positioned between the fan and the low-pressure compressor along the axial direction defined by the three-flow motor. Furthermore, in this embodiment, the root of the intermediate fan blades is positioned radially inside the root of the fan blades.

[0186] Furthermore, in some embodiments, the three-flow engine has an engine core and the motor is positioned within the engine core. In this respect, the motor is embedded in the three-flow engine. For example, in some embodiments, the motor may be positioned radially inside the core conduit. Additionally, in some embodiments, the motor is coupled to a first shaft (e.g., an HP shaft) behind the intermediate fan and in front of the high-pressure compressor, for example, as... Figure 7 As shown. In other embodiments, the motor is connected to the first shaft in front of the intermediate fan. Further, in some embodiments, the motor is directly connected to the first shaft, for example, as shown... Figure 7 and 8 As shown. In some alternative embodiments, the motor is indirectly connected to the first shaft, for example, via a gearbox.

[0187] At (502A), method (500) includes operating a three-flow gas turbine engine to define the main fan radius to the intermediate fan radius as equal to or greater than 2.0 and less than or equal to 6.5. In such an embodiment, the three-flow gas turbine engine has a main fan having a plurality of fan blades. The ratio of the main fan radius to the intermediate fan radius is defined by the radius between the leading edge tip of one fan blade across the longitudinal axis defined by the three-flow gas turbine engine and the radius across the leading edge tip of one intermediate fan blade across the longitudinal axis. In some other embodiments, the three-flow engine defines the ratio of the main fan radius to the intermediate fan radius as at least about 2.0. In other embodiments, the three-flow engine defines the ratio of the main fan radius to the intermediate fan radius as at least about 2.5. In yet another embodiment, the three-flow engine defines the ratio of the main fan radius to the intermediate fan radius as at least about 3.0. In some further embodiments, the three-flow engine defines the ratio of the main fan radius to the intermediate fan radius as at least about 4.0. In yet another embodiment, the three-flow engine defines the ratio of the main fan radius to the intermediate fan radius as at least about 6.0. In some other implementations, the three-flow engine limits the ratio of the main fan radius to the intermediate fan radius to approximately 6.5.

[0188] At (502B), in addition to or alternatively operating the three-flow gas turbine engine at (502A), method (500) includes operating the three-flow engine to limit the ratio of the intermediate fan tip speed to the high-pressure turbine tip speed to be equal to or greater than 0.7 and less than or equal to 1.5. The ratio of the intermediate fan tip speed to the high-pressure turbine tip speed is defined by the tip speed of the intermediate fan blades of the intermediate fan and the tip speed of the last-stage turbine blades of the high-pressure turbine.

[0189] At (502C), in addition to operating the three-flow gas turbine engine at (502A) and / or (502B), or alternatively, method (500) includes operating the three-flow engine to define the ratio of the intermediate fan hub radius to the motor radius as equal to or greater than 0.1 and less than or equal to 1.0. In such an embodiment, the ratio of the intermediate fan hub radius to the motor radius is defined by the radius between the outermost point across the longitudinal axis defined by the three-flow gas turbine engine and at the trailing edge of the hub of the intermediate fan blade, and the radius between the outermost point across the longitudinal axis and the outermost point of the rotor or stator of the motor (depending on which one is positioned outside the other along the radial direction defined by the three-flow gas turbine engine).

[0190] At (502D), in addition to operating the three-flow gas turbine engine at (502A) and / or at (502B) and / or at (502C), or alternatively, the method (500) includes operating the three-flow gas turbine engine to define the ratio of the high-pressure compressor hub radius to the motor radius as equal to or greater than 0.1 and less than or equal to 1.0. In such an embodiment, the ratio of the high-pressure compressor hub radius to the motor radius is defined by the radius between the outermost point across the longitudinal axis defined by the three-flow gas turbine engine and the leading edge of the hub of the first-stage blade of the high-pressure compressor operably coupled to the first shaft, and the radius between the outermost point across the longitudinal axis and the outermost point of the rotor or stator of the motor (depending on which one is positioned outside the other along the radial direction defined by the three-flow gas turbine engine).

[0191] At (502E), in addition to operating the three-flow gas turbine engine at (502A) and / or at (502B) and / or at (502C) and / or at (502D), or alternatively, the method (500) includes operating the three-flow gas turbine engine to limit the ratio of the high-pressure turbine tip speed to the motor tip speed to be equal to or greater than 0.1 and less than or equal to 1.0. The ratio of the high-pressure turbine tip speed to the motor tip speed is defined by the tip speed of the first-stage turbine blades of the high-pressure turbine and the tip speed of the rotor of the motor.

[0192] At (502F), in addition to or alternatively operating the three-flow gas turbine engine at (502A) and / or at (502B) and / or at (502C) and / or at (502D) and / or at (502E), the method (500) includes operating the three-flow gas turbine engine to define a high-pressure turbine length to motor length ratio equal to or greater than 0.1 and less than or equal to 1.5. The high-pressure turbine length to motor length ratio is defined by the length of the high-pressure turbine operably coupled to the first shaft and the motor length spanning the leading and trailing edges of the motor rotor along the axial direction defined by the three-flow gas turbine engine.

[0193] At (502G), in addition to operating the three-flow gas turbine engine at (502A) and / or at (502B) and / or at (502C) and / or at (502D) and / or at (502E) and / or at (502F), or alternatively, the method (500) includes operating the three-flow gas turbine engine to limit the power-to-voltage ratio of the motor to be equal to or greater than 0.3 and less than or equal to 2.0. In such embodiments, the power-to-voltage ratio is defined by the electrical power output by the motor (in kilowatts) and the voltage level of the motor (in DC volts). Furthermore, in some embodiments, the electrical power output of the motor ranges from 100 kilowatts to 1 megawatt. Furthermore, in some embodiments, the voltage level of the motor ranges between 270 DC volts and 3,000 DC volts. In some implementations, the electric power output of the motor ranges from 100 kilowatts to 1 megawatt, and the voltage level of the motor ranges from 270 DC volts to 3,000 DC volts.

[0194] At (502H), in addition to or alternatively operating the three-flow gas turbine engine at (502A) and / or at (502B) and / or at (502C) and / or at (502D) and / or at (502E), the method (500) includes operating the three-flow gas turbine engine to limit the ratio of the power of the second motor to the power of the first motor to be equal to or greater than 0.1 and less than or equal to 1.5. In such an embodiment, the motor is the first motor, and the three-flow engine further includes a second motor operatively coupled to a second shaft. In some embodiments, the first shaft is the high-pressure shaft of the three-flow engine, and the second shaft is the low-pressure shaft of the three-flow engine.

[0195] This written description uses examples to disclose the invention, including the best mode, and also enables any person skilled in the art to practice the invention, including making and using any device or system and performing any combined methods. The patent scope of the invention is defined by the claims, but may include other examples that would occur to a person skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that are not indistinguishable from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

[0196] Further aspects of the invention are provided by the subject matter of the following clauses:

[0197] First set of terms

[0198] 1. A method comprising: operating a three-flow gas turbine engine having an electric motor embedded therein to define a tip speed ratio equal to or greater than 0.2 and less than or equal to 1.0, the tip speed ratio being defined by the tip speed of the rotor of the electric motor and the tip speed of the intermediate fan blades of an intermediate fan, the electric motor and the intermediate fan being operatively coupled to a shaft of the three-flow gas turbine engine.

[0199] 2. The method according to any of the preceding clauses, wherein the three-flow gas turbine engine has a main fan having a plurality of fan blades, and wherein the three-flow gas turbine engine defines the main fan radius and the intermediate fan radius as equal to or greater than 2.0 and less than or equal to 6.5, the ratio of the main fan radius to the intermediate fan radius being defined by a radius spanning between the longitudinal axis defined by the three-flow gas turbine engine and the leading edge tip of one of the fan blades, and a radius spanning between the longitudinal axis and the leading edge tip of one of the intermediate fan blades.

[0200] 3. The method according to any of the preceding clauses, wherein the three-flow gas turbine engine and the motor define an intermediate fan radius to motor radius ratio equal to or greater than 1.33 and less than or equal to 3.8, the intermediate fan radius to motor radius ratio being defined by the radius between the leading edge tip of one of the intermediate fan blades of the intermediate fan spanning the longitudinal axis defined by the three-flow gas turbine engine and the radius between the outermost point of the rotor of the motor spanning the longitudinal axis.

[0201] 4. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-voltage ratio of the motor to be equal to or greater than 0.3 and less than or equal to 2.0, the power-to-voltage ratio being defined by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts.

[0202] 4A. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-voltage ratio of the motor to be equal to or greater than 0.35 and less than or equal to 0.5, the power-to-voltage ratio being defined by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts.

[0203] 4B. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-voltage ratio of the motor to be equal to or greater than 0.4 and less than or equal to 0.5, the power-to-voltage ratio being defined by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts.

[0204] 5. The method according to any of the preceding clauses, wherein the electric power output of the motor ranges from 100 kilowatts to 3 megawatts, and the voltage level of the motor ranges from 270 DC volts to 3,000 DC volts.

[0205] 6. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-voltage ratio of the motor to be equal to or greater than 0.35 and less than or equal to 0.5, the power-to-voltage ratio being defined by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts.

[0206] 7. The method according to any of the preceding clauses, wherein the electric power output of the motor ranges from 100 kilowatts to 3 megawatts, and the voltage level of the motor ranges from 270 DC volts to 3,000 DC volts.

[0207] 8. The method according to any of the preceding clauses, wherein, when operating the three-flow gas turbine engine, the rotor of the electric motor has a rotor tip speed equal to or greater than 50 m / s and less than or equal to 200 m / s.

[0208] 9. The method according to any of the preceding clauses, wherein, when operating the three-flow gas turbine engine, the rotor of the electric motor has a rotor tip speed equal to or greater than 140 m / s and less than or equal to 190 m / s.

[0209] 10. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-AC rated current ratio of the motor to be equal to or greater than 0.2 and less than or equal to 2.5, the power-to-AC rated current ratio being defined by the electrical power output by the motor in kilowatts and the AC rated current of the motor in ampere root mean square.

[0210] 10A. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-AC rated current ratio of the motor to be equal to or greater than 0.2 and less than or equal to 1.2, the power-to-AC rated current ratio being defined by the electrical power output by the motor in kilowatts and the AC rated current of the motor in ampere root mean square.

[0211] 10B. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-AC rated current ratio of the motor to be equal to or greater than 1.8 and less than or equal to 2.5, the power-to-AC rated current ratio being defined by the electrical power output by the motor in kilowatts and the AC rated current of the motor in ampere root mean square.

[0212] 10C. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-AC rated current ratio of the motor to be equal to or greater than 1.2 and less than or equal to 1.8, the power-to-AC rated current ratio being defined by the electrical power output by the motor in kilowatts and the AC rated current of the motor in ampere root mean square.

[0213] 10D. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-AC rated current ratio of the motor to be equal to or greater than 0.6 and less than or equal to 2.0, the power-to-AC rated current ratio being defined by the electrical power output by the motor in kilowatts and the AC rated current of the motor in ampere root mean square.

[0214] 11. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the torque-to-AC rated current ratio at maximum speed to be equal to or greater than 0.1 and less than or equal to 6.0.

[0215] 12. A three-flow gas turbine engine comprising: a shaft; a main fan operably coupled to the shaft; an intermediate fan positioned downstream of the main fan and operably coupled to the shaft, the intermediate fan having intermediate fan blades; and a motor operably coupled to the shaft, the motor having a stator and a rotor, the rotor being rotatable with the shaft, and wherein, when operated, the three-flow gas turbine engine defines a tip speed ratio equal to or greater than 0.2 and less than or equal to 1.0, the tip speed ratio being defined by the tip speed of the rotor of the motor and the tip speed of one of the intermediate fan blades.

[0216] 13. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine defines an intermediate fan radius to motor radius ratio equal to or greater than 1.33 and less than or equal to 3.8, the intermediate fan radius to motor radius ratio being defined by a radius between the leading edge tip of one of the intermediate fan blades of the intermediate fan spanning a longitudinal axis defined by the three-flow gas turbine engine and the radius between the outermost point of the rotor of the motor spanning the longitudinal axis.

[0217] 14. A three-flow gas turbine engine according to any of the preceding clauses, wherein, when operated, the three-flow gas turbine engine limits the power-to-voltage ratio of the motor to be equal to or greater than 0.3 and less than or equal to 2.0, the power-to-voltage ratio being defined by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts, and wherein the electrical power output of the motor ranges from 100 kilowatts to 3 megawatts, and the voltage level of the motor ranges from 270 DC volts to 3,000 DC volts.

[0218] 14A. A three-flow gas turbine engine according to any of the preceding clauses, wherein, when the three-flow gas turbine engine is operated, the rotor of the motor has a rotor tip speed equal to or greater than 50 m / s and less than or equal to 200 m / s.

[0219] 15. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine further comprises: a main fan positioned upstream of the intermediate fan and operably connected to the shaft; an engine core; a core shroud surrounding the engine core; a core duct defined between the engine core and the core shroud; a fan shroud surrounding the core shroud; a fan duct defined between the core shroud and the fan shroud; and an inlet duct in flow communication with the core duct and the fan duct, the inlet duct being defined between the engine core and the fan shroud, and the intermediate fan being positioned within the inlet duct.

[0220] 16. A three-flow gas turbine engine comprising: a shaft; a main fan operably coupled to the shaft; an intermediate fan positioned downstream of the main fan and operably coupled to the shaft, the intermediate fan having intermediate fan blades; and a motor operably coupled to the shaft, the motor having a rotor rotatable with the shaft, wherein the three-flow gas turbine engine defines an intermediate fan radius to motor radius ratio equal to or greater than 1.33 and less than or equal to 3.8, the intermediate fan radius to motor radius ratio being defined by a radius between a longitudinal axis defined by the three-flow gas turbine engine and the leading edge tip of one of the intermediate fan blades of the intermediate fan and a radius between the outermost point of the rotor of the motor and the longitudinal axis.

[0221] 17. The three-flow gas turbine engine according to any of the preceding clauses, wherein the shaft is a low-pressure shaft.

[0222] 18. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine limits the ratio of the intermediate fan radius to the motor radius to be equal to or greater than 2.5 and less than or equal to 3.3.

[0223] 19. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine limits the ratio of the intermediate fan radius to the motor radius to be equal to or greater than 2.9 and less than or equal to 3.2.

[0224] 20. A three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine defines an axial direction, and wherein the motor is positioned behind the intermediate fan and at least partially overlaps with or is located behind the low-pressure turbine of the three-flow gas turbine engine along the axial direction.

[0225] 21. A three-flow gas turbine engine comprising: a low-pressure shaft; a high-pressure shaft; a main fan operatively connected to the low-pressure shaft, the main fan having main fan blades; an intermediate fan positioned downstream of the main fan and operatively connected to the low-pressure shaft, the intermediate fan having intermediate fan blades; and a motor operatively connected to either the low-pressure shaft or the high-pressure shaft, wherein the three-flow gas turbine engine defines a main fan radius to intermediate fan radius ratio of equal to or greater than 2.0 and less than or equal to 6.5, the main fan radius to intermediate fan radius ratio being defined by a radius between a longitudinal axis defined by the three-flow gas turbine engine and the leading edge tip of one of the blades of the main fan, and a radius between the leading edge tip of one of the intermediate fan blades of the intermediate fan and the longitudinal axis.

[0226] 22. The three-flow gas turbine engine of claim 21, wherein the motor is operatively connected to the low-pressure shaft.

[0227] 23. The three-flow gas turbine engine according to claim 21, wherein the motor is operably connected to the high-pressure shaft.

[0228] 24. The three-flow gas turbine engine according to claim 21, wherein the main fan is a ductless fan.

[0229] 25. The three-flow gas turbine engine according to claim 21, wherein the ratio of the main fan radius to the intermediate fan radius is defined as equal to or greater than 3.0 and less than or equal to 6.5.

[0230] 26. The three-flow gas turbine engine of claim 21, wherein the three-flow gas turbine engine and the motor define an intermediate fan radius to motor radius ratio equal to or greater than 1.33 and less than or equal to 3.8, the intermediate fan radius to motor radius ratio being defined by the radius between the leading edge tips of one of the intermediate fan blades spanning the longitudinal axis and the intermediate fan, and the radius between the outermost point of the rotor spanning the longitudinal axis and the motor.

[0231] 27. The three-flow gas turbine engine of claim 21, wherein the three-flow gas turbine engine and the motor define an intermediate fan radius to motor radius ratio equal to or greater than 2.9 and less than or equal to 3.2, the intermediate fan radius to motor radius ratio being defined by the radius between the leading edge tips of one of the intermediate fan blades spanning the longitudinal axis and the intermediate fan and the radius between the outermost point of the rotor spanning the longitudinal axis and the motor.

[0232] 28. The three-flow gas turbine engine of claim 21, further comprising: a low-pressure turbine operably connected to the low-pressure shaft, wherein the three-flow gas turbine engine defines an axial direction, and wherein the three-flow gas turbine engine defines a motor length to low-pressure turbine length ratio of equal to or greater than 0.01 and less than or equal to 3.0, the motor length to low-pressure turbine length ratio being defined by the length of the low-pressure turbine and the length of the motor, the length of the motor spanning along the axial direction between the leading and trailing edges of the rotor of the motor, and the length of the low-pressure turbine spanning between the leading edge of the hub of the first-stage turbine blade of the low-pressure turbine and the trailing edge of the hub of the last-stage turbine blade of the low-pressure turbine.

[0233] 29. The three-flow gas turbine engine of claim 21, further comprising: a low-pressure turbine operably connected to the low-pressure shaft, wherein the three-flow gas turbine engine defines an axial direction, and wherein the three-flow gas turbine engine defines a ratio of the motor tip radius to the low-pressure turbine last-stage hub radius to be equal to or greater than 0.1 and less than or equal to 1.0, the ratio being defined by a radius spanning the longitudinal axis defined by the three-flow gas turbine engine and the outermost point of the motor rotor, and a radius spanning the longitudinal axis and the outermost point of the hub of the last-stage turbine blade of the low-pressure turbine.

[0234] 30. The three-flow gas turbine engine according to claim 21, further comprising: an engine core; a core cover surrounding the engine core; a core duct defined between the engine core and the core cover; a fan cover surrounding the core cover; a fan duct defined between the core cover and the fan cover; an inlet duct in flow communication with the core duct and the fan duct, the inlet duct being defined between the engine core and the fan cover, an intermediate fan positioned within the inlet duct, and a motor positioned within the engine core.

[0235] Second set of clauses

[0236] 1. A three-flow gas turbine engine defining an axial direction, the three-flow gas turbine engine comprising: a shaft; a main fan operably connected to the shaft; an intermediate fan positioned downstream of the main fan and operably connected to the shaft, the intermediate fan having intermediate fan blades; a low-pressure turbine operably connected to the shaft; and a motor operably connected to the shaft, the motor having a stator and a rotor, the rotor being rotatable with the shaft, and wherein the three-flow gas turbine engine defines a motor length to low-pressure turbine length ratio equal to or greater than 0.01 and less than or equal to 3.0, the motor length to low-pressure turbine length ratio being defined by the length of the low-pressure turbine and the length of the motor, the length of the motor spanning along the axial direction between the leading and trailing edges of the rotor of the motor, the length of the low-pressure turbine spanning between the leading edge of the hub of a first-stage turbine blade of the low-pressure turbine and the trailing edge of the hub of a last-stage turbine blade of the low-pressure turbine.

[0237] 2. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine has a main fan with a plurality of fan blades, and wherein the three-flow gas turbine engine defines the radius of the main fan and the radius of the intermediate fan as equal to or greater than 2.0 and less than or equal to 6.5, the ratio of the main fan radius to the intermediate fan radius being defined by a radius spanning between the longitudinal axis defined by the three-flow gas turbine engine and the leading edge tip of one of the fan blades, and a radius spanning between the longitudinal axis and the leading edge tip of one of the intermediate fan blades.

[0238] 3. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine further defines the ratio of the motor tip radius to the low-pressure turbine last-stage hub radius as equal to or greater than 0.1 and less than or equal to 1.0, the ratio of the motor tip radius to the low-pressure turbine last-stage hub radius being defined by the radius between the outermost point of the rotor of the motor and the longitudinal axis defined by the three-flow engine and the outermost point of the hub of the last-stage turbine blade of the low-pressure turbine spanning the longitudinal axis.

[0239] 4. The three-flow gas turbine engine according to any of the preceding clauses, wherein, when operated, the three-flow gas turbine engine limits the ratio of motor power to low-pressure turbine power to be equal to or greater than 0.01 and greater than or equal to 1.0 at flight idle.

[0240] 4A. The three-flow gas turbine engine according to any of the preceding clauses, wherein, when operated, the three-flow gas turbine engine limits the ratio of motor power to low-pressure turbine power to be equal to or greater than 0.01 and less than or equal to 0.2 at flight idle.

[0241] 4B. The three-flow gas turbine engine according to any of the preceding clauses, wherein, when operated, the three-flow gas turbine engine limits the ratio of motor power to low-pressure turbine power to be equal to or greater than 0.1 and less than or equal to 0.45 at flight idle.

[0242] 4C. The three-flow gas turbine engine according to any of the preceding clauses, wherein, when operated, the three-flow gas turbine engine limits the ratio of motor power to low-pressure turbine power to be equal to or greater than 0.45 and less than or equal to 1.0 at flight idle.

[0243] 5. A three-flow gas turbine engine according to any of the preceding clauses, wherein, when operated, the three-flow gas turbine engine limits the power-to-voltage ratio of the motor to be equal to or greater than 0.3 and less than or equal to 2.0, the power-to-voltage ratio being defined by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts, and wherein the electrical power output of the motor ranges from 100 kilowatts to 3 megawatts, and the voltage level of the motor ranges from 270 DC volts to 3,000 DC volts.

[0244] 6. The three-flow gas turbine engine according to any of the preceding clauses, further comprising: a main fan positioned upstream of the intermediate fan and operably connected to the shaft; an engine core; a core shroud surrounding the engine core; a core duct defined between the engine core and the core shroud; a fan shroud surrounding the core shroud; a fan duct defined between the core shroud and the fan shroud; and an inlet duct in flow communication with the core duct and the fan duct, the inlet duct being defined between the engine core and the fan shroud, the intermediate fan being positioned within the inlet duct.

[0245] 7. A three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow engine defines a radial direction, the three-flow engine further comprising: an engine core; a core shroud surrounding the engine core; a core duct defined between the engine core and the core shroud; a fan shroud surrounding the core shroud; a fan duct defined between the core shroud and the fan shroud; an inlet duct in flow communication with the core duct and the fan duct, the inlet duct being defined between the engine core and the fan shroud, and a motor being directly mechanically coupled to a shaft and positioned radially inside the core duct.

[0246] 7A. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine limits the ratio of the motor length to the low-pressure turbine length to be equal to or greater than 0.01 and less than or equal to 0.5.

[0247] 7B. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine limits the ratio of the motor length to the low-pressure turbine length to be equal to or greater than 0.3 and less than or equal to 1.0.

[0248] 7C. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine limits the ratio of the motor length to the low-pressure turbine length to be equal to or greater than 1.0 and less than or equal to 3.0.

[0249] 7D. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine limits the ratio of the motor length to the low-pressure turbine length to be equal to or greater than 2.0 and less than or equal to 3.0.

[0250] 8. A three-flow gas turbine engine comprising: a shaft; a main fan operably connected to the shaft; an intermediate fan positioned downstream of the main fan and operably connected to the shaft, the intermediate fan having intermediate fan blades; a low-pressure turbine; and an electric motor operably connected to the shaft, the electric motor having a stator and a rotor, the rotor being rotatable with the shaft, and wherein the three-flow gas turbine engine further defines the ratio of the electric motor tip radius to the low-pressure turbine last-stage hub radius as equal to or greater than 0.1 and less than or equal to 1.0.

[0251] 8A. The three-flow gas turbine engine according to any of the preceding clauses, wherein the ratio of the motor tip radius to the low-pressure turbine last-stage hub radius is defined as equal to or greater than 0.1 and less than or equal to 0.5.

[0252] 8B. The three-flow gas turbine engine according to any of the preceding clauses, wherein the ratio of the motor tip radius to the low-pressure turbine last-stage hub radius is defined as equal to or greater than 0.4 and less than or equal to 1.0.

[0253] 8C. The three-flow gas turbine engine according to any of the preceding clauses, wherein the ratio of the motor tip radius to the low-pressure turbine last-stage hub radius is defined as equal to or greater than 0.7 and less than or equal to 1.0.

[0254] 9. A three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine defines an axial direction, and wherein the three-flow gas turbine engine defines a motor length to low-pressure turbine length ratio equal to or greater than 0.01 and less than or equal to 3.0, the motor length to low-pressure turbine length ratio being defined by the length of the low-pressure turbine and the length of the motor, the length of the motor spanning along the axial direction between the leading and trailing edges of the rotor of the motor, and the length of the low-pressure turbine spanning between the leading edge of the hub of the first-stage turbine blade of the low-pressure turbine and the trailing edge of the hub of the last-stage turbine blade of the low-pressure turbine.

[0255] 10. The three-flow gas turbine engine according to any of the preceding clauses, wherein, when operated, the three-flow gas turbine engine limits the ratio of motor power to low-pressure turbine power to be equal to or greater than 0.01 and less than or equal to 1.0 at flight idle.

[0256] 11. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine defines an axial direction, and wherein the motor is positioned behind the intermediate fan and at least partially overlaps with or is located behind the low-pressure turbine along the axial direction.

[0257] 12. The three-flow gas turbine engine according to any of the preceding clauses, wherein the main fan is a ductless fan.

[0258] 13. The three-flow gas turbine engine according to any of the preceding clauses, further comprising: an engine core; a core shroud surrounding the engine core; a core duct defined between the engine core and the core shroud; a fan shroud surrounding the core shroud; a fan duct defined between the core shroud and the fan shroud; an inlet duct in flow communication with the core duct and the fan duct, the inlet duct being defined between the engine core and the fan shroud, wherein the motor is directly mechanically connected to the shaft and embedded within the engine core.

[0259] 14. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine defines an intermediate fan radius to motor radius ratio equal to or greater than 2.5 and less than or equal to 3.3, the intermediate fan radius to motor radius ratio being defined by a radius between the leading edge tip of one of the intermediate fan blades of the intermediate fan spanning a longitudinal axis defined by the three-flow gas turbine engine and the radius between the outermost point of the rotor of the motor spanning the longitudinal axis.

[0260] 15. A three-flow gas turbine engine according to any of the preceding clauses, wherein the main fan has a plurality of fan blades, and wherein the three-flow gas turbine engine defines the main fan radius and the intermediate fan radius as equal to or greater than 2.0 and less than or equal to 6.5, the ratio of the main fan radius to the intermediate fan radius being defined by a radius spanning the longitudinal axis defined by the three-flow gas turbine engine and between the leading edge tip of one of the fan blades and the radius spanning the longitudinal axis and between the leading edge tip of one of the intermediate fan blades.

[0261] 16. A method comprising: operating a three-flow gas turbine engine having an electric motor therein to limit the ratio of an intermediate fan tip speed to a low-pressure turbine tip speed to be equal to or greater than 0.7 and less than or equal to 1.5, the ratio being limited by the tip speed of an intermediate fan blade and the tip speed of a last-stage turbine blade of the low-pressure turbine, the intermediate fan being operatively coupled to a shaft of the three-flow gas turbine engine, and the low-pressure turbine being operatively coupled to the shaft.

[0262] 17. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the intermediate fan tip speed to the low-pressure turbine tip speed to be equal to or greater than 0.8 and less than or equal to 1.2.

[0263] 18. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the low-pressure turbine tip speed to the motor tip speed to be equal to or greater than 0.1 and less than or equal to 1.0.

[0264] 18A. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the low-pressure turbine tip speed to the motor tip speed to be equal to or greater than 0.1 and less than or equal to 0.3.

[0265] 18B. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the low-pressure turbine tip speed to the motor tip speed to be equal to or greater than 0.5 and less than or equal to 0.9.

[0266] 19. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-voltage ratio of the motor to be equal to or greater than less than 0.3 and less than or equal to 2.0, the power-to-voltage ratio being defined by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts.

[0267] 20. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-AC rated current ratio of the motor to be equal to or greater than 0.2 and less than or equal to 2.5, the power-to-AC rated current ratio being defined by the electrical power output by the motor in kilowatts and the AC rated current of the motor in ampere root mean square.

[0268] Third group of clauses

[0269] 1. A method comprising: operating a three-flow gas turbine engine having an electric motor embedded therein to limit the ratio of an intermediate fan tip speed to a high-pressure turbine tip speed to be equal to or greater than 0.7 and less than or equal to 1.5, the ratio being limited by the tip speed of an intermediate fan blade of the intermediate fan and the tip speed of a last-stage turbine blade of the high-pressure turbine, the electric motor and the high-pressure turbine being operatively connected to a first shaft of the three-flow gas turbine engine, and the intermediate fan being operatively connected to a second shaft of the three-flow gas turbine engine.

[0270] 2. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the intermediate fan tip speed to the high-pressure turbine tip speed to be equal to or greater than 0.8 and less than or equal to 1.2.

[0271] 3. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the intermediate fan tip speed to the high-pressure turbine tip speed to be equal to or greater than 0.9 and less than or equal to 1.1.

[0272] 4. The method according to any of the preceding clauses, wherein the three-flow gas turbine engine has a main fan having a plurality of fan blades, and wherein the three-flow gas turbine engine defines the main fan radius and the intermediate fan radius as equal to or greater than 2.0 and less than or equal to 6.5, the ratio of the main fan radius to the intermediate fan radius being defined by a radius spanning between the longitudinal axis defined by the three-flow gas turbine engine and the leading edge tip of one of the fan blades, and a radius spanning between the longitudinal axis and the leading edge tip of one of the intermediate fan blades.

[0273] 5. The method according to any of the preceding clauses, wherein the first shaft is a high-pressure shaft and the second shaft is a low-pressure shaft.

[0274] 6. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the high-pressure turbine tip speed to the motor tip speed to be equal to or greater than 0.1 and less than or equal to 1.0, the ratio of the high-pressure turbine tip speed to the motor tip speed being limited by the tip speed of the first-stage turbine blades of the high-pressure turbine and the tip speed of the rotor of the motor.

[0275] 7. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-voltage ratio to be equal to or greater than 0.3 and less than or equal to 2.0, the power-to-voltage ratio being limited by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts.

[0276] 7A. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-voltage ratio to be equal to or greater than 0.3 and less than or equal to 1.1, the power-to-voltage ratio being limited by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts.

[0277] 7B. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-voltage ratio to be equal to or greater than 0.3 and less than or equal to 0.6, the power-to-voltage ratio being limited by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts.

[0278] 7C. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-voltage ratio to be equal to or greater than 0.6 and less than or equal to 1.1, the power-to-voltage ratio being limited by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts.

[0279] 7D. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-voltage ratio to be equal to or greater than 1.0 and less than or equal to 2.0, the power-to-voltage ratio being limited by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts.

[0280] 8. The method according to any of the preceding clauses, wherein the electrical power output by the motor ranges from 100 kilowatts to 1 megawatt, and the voltage level of the motor ranges from 270 DC volts to 3,000 DC volts.

[0281] 9. The method according to any of the preceding clauses, wherein the motor is a first motor, and wherein the three-flow engine further includes a second motor operably coupled to the second shaft, and wherein operating the three-flow gas turbine engine further includes operating the three-flow gas turbine engine to limit the power ratio of the second motor to the power of the first motor to be equal to or greater than 0.1 and less than or equal to 1.5.

[0282] 9A. The method according to any of the preceding clauses, wherein the motor is a first motor, and wherein the three-flow engine further includes a second motor operably coupled to the second shaft, and wherein operating the three-flow gas turbine engine further includes operating the three-flow gas turbine engine to limit the power ratio of the second motor to the power ratio of the first motor to be equal to or greater than 0.5 and less than or equal to 1.2.

[0283] 9B. The method according to any of the preceding clauses, wherein the motor is a first motor, and wherein the three-flow engine further includes a second motor operably coupled to the second shaft, and wherein operating the three-flow gas turbine engine further includes operating the three-flow gas turbine engine to limit the power ratio of the second motor to the power ratio of the first motor to be equal to or greater than 0.5 and less than or equal to 0.75.

[0284] 9C. The method according to any of the preceding clauses, wherein the motor is a first motor, and wherein the three-flow engine further includes a second motor operably coupled to the second shaft, and wherein operating the three-flow gas turbine engine further includes operating the three-flow gas turbine engine to limit the power ratio of the second motor to the power ratio of the first motor to be equal to or greater than 0.75 and less than or equal to 1.2.

[0285] 9D. The method according to any of the preceding clauses, wherein the motor is a first motor, and wherein the three-flow engine further includes a second motor operably coupled to the second shaft, and wherein operating the three-flow gas turbine engine further includes operating the three-flow gas turbine engine to limit the power ratio of the second motor to the power of the first motor to be equal to or greater than 0.6 and less than or equal to 0.9.

[0286] 10. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to define the ratio of the intermediate fan hub radius to the motor radius as equal to or greater than 0.1 and less than or equal to 1.0, the ratio of the intermediate fan hub radius to the motor radius being defined by a radius between the outermost point taken across the longitudinal axis defined by the three-flow gas turbine engine and at the trailing edge of the hub of the intermediate fan blade of the intermediate fan, and a radius between the outermost point across the longitudinal axis and the rotor or stator of the motor, the rotor or the stator depending on which one is located outside the other along the radial direction defined by the three-flow gas turbine engine.

[0287] 11. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to define a high-pressure compressor hub radius to motor radius ratio equal to or greater than 0.1 and less than or equal to 1.0, the high-pressure compressor hub radius to motor radius ratio being defined by a radius between the outermost point across a longitudinal axis defined by the three-flow gas turbine engine and the outermost point at the leading edge of the hub in the first stage blades of the high-pressure compressor, and a radius between the outermost point across the longitudinal axis and the outermost point of the rotor or stator of the motor, the high-pressure compressor being operatively coupled to a first shaft, the rotor or the stator depending on which one is located outside the other along a radial direction defined by the three-flow gas turbine engine.

[0288] 12. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to define a high-pressure turbine length to motor length ratio equal to or greater than 0.1 and less than or equal to 1.5, the high-pressure turbine length to motor length ratio being defined by the length of the high-pressure turbine and the length of the motor, the high-pressure turbine being operatively connected to a first shaft, the length of the motor spanning between the leading and trailing edges of the motor rotor along an axial direction defined by the three-flow gas turbine engine.

[0289] 12A. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the high-pressure turbine length to the motor length to be equal to or greater than 0.1 and less than or equal to 0.5.

[0290] 12B. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the high-pressure turbine length to the motor length to be equal to or greater than 0.5 and less than or equal to 0.85.

[0291] 12C. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the high-pressure turbine length to the motor length to be equal to or greater than 0.85 and less than or equal to 1.5.

[0292] 13. A three-flow gas turbine engine comprising: a low-pressure shaft; a main fan operatively connected to the low-pressure shaft; an intermediate fan positioned downstream of the main fan and operatively connected to the low-pressure shaft, the intermediate fan having intermediate fan blades; a high-pressure shaft; and a motor operatively connected to the high-pressure shaft, the motor having a rotor rotatable with the high-pressure shaft, wherein the three-flow engine defines an intermediate fan hub radius to motor radius ratio equal to or greater than 0.1 and less than or equal to 1.0, the intermediate fan hub radius to motor radius ratio being defined by a radius between a longitudinal axis defined by the three-flow gas turbine engine and the outermost point obtained at the trailing edge of the hub of the intermediate fan blade of the intermediate fan, and a radius between a longitudinal axis and the outermost point of either the rotor or the stator of the motor, the rotor or the stator depending on which one is located outside the other along a radial direction defined by the three-flow gas turbine engine.

[0293] 13A. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow engine limits the ratio of the intermediate fan hub radius to the motor radius to be equal to or greater than 0.1 and less than or equal to 0.4.

[0294] 13B. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow engine limits the ratio of the intermediate fan hub radius to the motor radius to be equal to or greater than 0.4 and less than or equal to 0.8.

[0295] 13C. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow engine limits the ratio of the intermediate fan hub radius to the motor radius to be equal to or greater than 0.6 and less than or equal to 1.0.

[0296] 14. The three-flow gas turbine engine according to any of the preceding clauses, further comprising: a high-pressure turbine having a last-stage turbine blade, and wherein, when operated, the three-flow gas turbine engine defines an intermediate fan tip speed to a high-pressure turbine tip speed ratio equal to or greater than 0.7 and less than or equal to 1.5, the intermediate fan tip speed to high-pressure turbine tip speed ratio being defined by the tip speed of one intermediate fan blade and the tip speed of one turbine blade in the last-stage turbine blade.

[0297] 15. The three-flow gas turbine engine according to any of the preceding claims, further comprising: a high-pressure turbine operably coupled to the first shaft and having a first-stage turbine blade, wherein the three-flow gas turbine engine defines a longitudinal axis and a radial direction, and wherein the three-flow gas turbine engine defines a high-pressure compressor hub radius to motor radius ratio equal to or greater than 0.1 and less than or equal to 1.0, the high-pressure compressor hub radius to motor radius ratio being defined by a radius between the outermost point across the longitudinal axis and at the leading edge of the hub of one of the first-stage blades and a radius between the outermost point across the longitudinal axis and the rotor or stator of the motor, the rotor or stator depending on which one is located outside the other along the radial direction.

[0298] 15A. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine limits the ratio of the high-pressure compressor hub radius to the motor radius to be equal to or greater than 0.1 and less than or equal to 0.25.

[0299] 15B. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine limits the ratio of the high-pressure compressor hub radius to the motor radius to be equal to or greater than 0.25 and less than or equal to 0.5.

[0300] 15C. The three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine limits the ratio of the high-pressure compressor hub radius to the motor radius to be equal to or greater than 0.5 and less than or equal to 1.0.

[0301] 16. The three-flow gas turbine engine according to any of the preceding clauses, further comprising: a high-pressure turbine, the high-pressure turbine being operatively connected to the first shaft and having a first-stage turbine blade, wherein the three-flow gas turbine engine defines an axial direction, and wherein the three-flow gas turbine defines a high-pressure turbine length to motor length ratio equal to or greater than 0.1 and less than or equal to 1.5, the high-pressure turbine length to motor length ratio being defined by the length of the high-pressure turbine and the length of the motor, the length of the motor spanning along the axial direction between the leading and trailing edges of the rotor of the motor.

[0302] 17. A three-flow gas turbine engine according to any of the preceding clauses, wherein the three-flow gas turbine engine has a main fan having a plurality of fan blades, and wherein the three-flow gas turbine engine defines the radius of the main fan and the radius of the intermediate fan as equal to or greater than 2.0 and less than or equal to 6.5, the ratio of the main fan radius to the intermediate fan radius being defined by a radius spanning between a longitudinal axis defined by the three-flow gas turbine engine and the leading edge tip of one of the fan blades, and a radius spanning between the longitudinal axis and the leading edge tip of one of the intermediate fan blades.

[0303] 18. A method comprising: operating a three-flow gas turbine engine having a main fan, an intermediate fan positioned downstream of the main fan, and an electric motor embedded therein, to limit a high-pressure turbine tip speed to an electric motor tip speed ratio to be equal to or greater than 0.1 and less than or equal to 1.0, the high-pressure turbine tip speed to electric motor tip speed ratio being limited by the tip speed of a first-stage turbine blade of the high-pressure turbine and the tip speed of the rotor of the electric motor, the electric motor and the high-pressure turbine being operatively coupled to a first shaft of the three-flow gas turbine engine, and the intermediate fan and the main fan being operatively coupled to a second shaft of the three-flow gas turbine engine.

[0304] 18A. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the high-pressure turbine tip speed to the motor tip speed to be equal to or greater than 0.1 and less than or equal to 0.3.

[0305] 18B. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the high-pressure turbine tip speed to the motor tip speed to be equal to or greater than 0.3 and less than or equal to 0.6.

[0306] 18C. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the high-pressure turbine tip speed to the motor tip speed to be equal to or greater than 0.4 and less than or equal to 1.0.

[0307] 19. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the power-to-voltage ratio to be equal to or greater than 0.3 and less than or equal to 2.0, the power-to-voltage ratio being limited by the electrical power output by the motor in kilowatts and the voltage level of the motor in DC volts.

[0308] 20. The method according to any of the preceding clauses, wherein operating the three-flow gas turbine engine further comprises operating the three-flow gas turbine engine to limit the ratio of the intermediate fan tip speed to the high-pressure turbine tip speed to be equal to or greater than 0.7 and less than or equal to 1.5, the ratio of the intermediate fan tip speed to the high-pressure turbine tip speed being limited by the tip speed of the intermediate fan blades of the intermediate fan and the tip speed of the last stage turbine blades of the high-pressure turbine.

[0309] Fourth group of items

[0310] 1. A three-flow gas turbine engine comprising: a low-pressure shaft; a high-pressure shaft; a main fan operatively connected to the low-pressure shaft, the main fan having main fan blades; an intermediate fan positioned downstream of the main fan and operatively connected to the low-pressure shaft, the intermediate fan having intermediate fan blades; and a motor operatively connected to either the low-pressure shaft or the high-pressure shaft, wherein the three-flow gas turbine engine defines a ratio of the main fan radius to the intermediate fan radius as equal to or greater than 2.0 and less than or equal to 6.5, the ratio being defined by a radius between a longitudinal axis defined by the three-flow gas turbine engine and the leading edge tip of one of the blades of the main fan, and a radius between the leading edge tip of one of the intermediate fan blades of the intermediate fan and the longitudinal axis.

[0311] 2. A method comprising: operating a three-flow gas turbine engine having an electric motor embedded therein to define a tip speed ratio equal to or greater than 0.2 and less than or equal to 1.0, the tip speed ratio being defined by the tip speed of the rotor of the electric motor and the tip speed of the intermediate fan blades of an intermediate fan, the electric motor and the intermediate fan being operatively coupled to a shaft of the three-flow gas turbine engine.

[0312] 3. A three-flow gas turbine engine, comprising: a shaft; a main fan operably connected to the shaft; an intermediate fan positioned downstream of the main fan and operably connected to the shaft, the intermediate fan having intermediate fan blades; and a motor operably connected to the shaft, the motor having a rotor rotatable with the shaft, wherein the three-flow gas turbine engine defines an intermediate fan radius to motor radius ratio equal to or greater than 1.33 and less than or equal to 3.8, the intermediate fan radius to motor radius ratio being defined by a radius between a longitudinal axis defined by the three-flow gas turbine engine and the leading edge tip of one of the intermediate fan blades of the intermediate fan and a radius between the longitudinal axis and the outermost point of the rotor of the motor.

[0313] 4. A three-flow gas turbine engine defining an axial direction, the three-flow gas turbine engine comprising: a shaft; a main fan operably connected to the shaft; an intermediate fan positioned downstream of the main fan and operably connected to the shaft, the intermediate fan having intermediate fan blades; a low-pressure turbine operably connected to the shaft; and an electric motor operably connected to the shaft, the electric motor having a stator and a rotor, the rotor being rotatable with the shaft, wherein the three-flow gas turbine engine defines a ratio of electric motor length to low-pressure turbine length of equal to or greater than 0.01 and less than or equal to 3.0, the ratio of electric motor length to low-pressure turbine length being defined by the length of the low-pressure turbine and the length of the electric motor, the length of the electric motor spanning along the axial direction between the leading and trailing edges of the rotor of the electric motor, the length of the low-pressure turbine spanning between the leading edge of the hub of the first-stage turbine blade of the low-pressure turbine and the trailing edge of the hub of the last-stage turbine blade of the low-pressure turbine.

[0314] 5. A three-flow gas turbine engine, comprising: a shaft; a main fan operably connected to the shaft; an intermediate fan positioned downstream of the main fan and operably connected to the shaft, the intermediate fan having intermediate fan blades; a low-pressure turbine; and an electric motor operably connected to the shaft, the electric motor having a stator and a rotor, the rotor being rotatable with the shaft, wherein the three-flow gas turbine engine further defines the ratio of the electric motor tip radius to the low-pressure turbine last-stage hub radius as equal to or greater than 0.1 and less than or equal to 1.0.

[0315] 6. A method comprising: operating a three-flow gas turbine engine having an embedded electric motor to limit the ratio of an intermediate fan tip speed to a low-pressure turbine tip speed to be equal to or greater than 0.7 and less than or equal to 1.5, the ratio being defined by the tip speed of an intermediate fan blade and the tip speed of a last-stage turbine blade of the low-pressure turbine, the intermediate fan being operatively coupled to a shaft of the three-flow gas turbine engine, and the low-pressure turbine being operatively coupled to the shaft.

[0316] 7. A method comprising: operating a three-flow gas turbine engine to limit the ratio of low-pressure turbine tip speed to electric motor tip speed to be equal to or greater than 0.1 and less than or equal to 1.0.

[0317] 8. A method comprising: operating a three-flow gas turbine engine to limit the ratio of motor power to low-pressure turbine power to be equal to or greater than 0.01 and less than or equal to 1.0 at flight idle.

[0318] 9. A method comprising: operating a three-flow gas turbine engine to limit a power-to-voltage ratio to be equal to or greater than 0.3 and less than or equal to 2.0, the power-to-voltage ratio being limited by electrical power output by a motor in kilowatts and a voltage level of the motor in direct current volts, wherein an intermediate fan of the three-flow gas turbine engine and the motor are operatively connected to the same shaft of the three-flow gas turbine engine.

[0319] 10. A method comprising: operating a three-flow gas turbine engine to limit the power-to-AC rated current ratio of the motor of the three-flow gas turbine engine to be equal to or greater than 0.2 and less than or equal to 2.5, the power-to-AC rated current ratio being limited by the electrical power output by the motor in kilowatts and the AC rated current of the motor in ampere root mean square.

[0320] 11. A method comprising: operating a three-flow gas turbine engine to limit the torque-to-AC rated current ratio at maximum speed to be equal to or greater than 0.1 and less than or equal to 6.0.

[0321] 12. A method comprising: operating a three-flow gas turbine engine having an electric motor embedded therein to limit the ratio of an intermediate fan tip speed to a high-pressure turbine tip speed to be equal to or greater than 0.7 and less than or equal to 1.5, the ratio being limited by the tip speed of an intermediate fan blade of the intermediate fan and the tip speed of a last-stage turbine blade of the high-pressure turbine, the electric motor and the high-pressure turbine being operatively connected to a first shaft of the three-flow gas turbine engine, and the intermediate fan being operatively connected to a second shaft of the three-flow gas turbine engine.

[0322] 13. A three-flow gas turbine engine comprising: a low-pressure shaft; a main fan operatively connected to the low-pressure shaft; an intermediate fan positioned downstream of the main fan and operatively connected to the low-pressure shaft, the intermediate fan having intermediate fan blades; a high-pressure shaft; and a motor operatively connected to the high-pressure shaft, the motor having a rotor rotatable with the high-pressure shaft, wherein the three-flow engine defines an intermediate fan hub radius to motor radius ratio equal to or greater than 0.1 and less than or equal to 1.0, the intermediate fan hub radius to motor radius ratio being defined by a radius between a longitudinal axis defined by the three-flow gas turbine engine and the outermost point obtained at the trailing edge of the hub of the intermediate fan blade of the intermediate fan, and a radius between a longitudinal axis and the outermost point of the rotor or stator of the motor, the rotor or stator radius depending on which one is located outside the other along a radial direction defined by the three-flow gas turbine engine.

[0323] 14. A three-flow gas turbine engine comprising: a low-pressure shaft; a main fan operably coupled to the low-pressure shaft; an intermediate fan positioned downstream of the main fan and operably coupled to the low-pressure shaft, the intermediate fan having intermediate fan blades; a high-pressure shaft; a high-pressure turbine operably coupled to the high-pressure shaft and having first-stage turbine blades; and a motor operably coupled to the high-pressure shaft, the motor having a rotor rotatable with the high-pressure shaft, wherein the three-flow gas turbine engine defines a longitudinal axis and a radial direction, and wherein the three-flow gas turbine engine defines a high-pressure compressor hub radius to motor radius ratio equal to or greater than 0.1 and less than or equal to 1.0, the high-pressure compressor hub radius to motor radius ratio being defined by a radius between the outermost point across the longitudinal axis and at the leading edge of the hub of one of the first-stage blades and a radius between the outermost point across the longitudinal axis and the rotor or stator of the motor, the rotor or stator depending on which one is located outside the other along the radial direction.

[0324] 15. A method comprising: operating a three-flow gas turbine engine having a main fan, an intermediate fan positioned downstream of the main fan, and an electric motor embedded therein, to limit a high-pressure turbine tip speed to an electric motor tip speed ratio equal to or greater than 0.1 and less than or equal to 1.0, the high-pressure turbine tip speed to electric motor tip speed ratio being limited by the tip speed of a first-stage turbine blade of the high-pressure turbine and the tip speed of the rotor of the electric motor, the electric motor and the high-pressure turbine being operatively coupled to a first shaft of the three-flow gas turbine engine, and the intermediate fan and the main fan being operatively coupled to a second shaft of the three-flow gas turbine engine.

[0325] 16. A three-flow gas turbine engine comprising: a low-pressure shaft; a main fan operably connected to the low-pressure shaft; an intermediate fan positioned downstream of the main fan and operably connected to the low-pressure shaft, the intermediate fan having intermediate fan blades; a high-pressure shaft; an electric motor operably connected to the high-pressure shaft, the electric motor having a rotor rotatable with the high-pressure shaft; and a high-pressure turbine operably connected to the high-pressure shaft and having first-stage turbine blades, wherein the three-flow gas turbine engine defines an axial direction, and wherein the three-flow gas turbine defines a high-pressure turbine length to electric motor length ratio equal to or greater than 0.1 and less than or equal to 1.5, the high-pressure turbine length to electric motor length ratio being defined by the length of the high-pressure turbine and the length of the electric motor, the length of the electric motor spanning along the axial direction between the leading and trailing edges of the rotor of the electric motor.

[0326] 17. A method comprising: operating a three-flow gas turbine engine to limit a power-to-voltage ratio to be equal to or greater than 0.3 and less than or equal to 2.0, the power-to-voltage ratio being defined by electrical power output by a motor in kilowatts and a voltage level of the motor in direct current volts, the three-flow gas turbine engine having an intermediate fan operatively connected to its low-pressure shaft, and the motor operatively connected to a high-pressure shaft of the three-flow gas turbine engine.

[0327] 18. A method comprising: operating a three-flow gas turbine engine having a first motor and a second motor to limit the power ratio of the second motor to the power of the first motor to be equal to or greater than 0.1 and less than or equal to 1.5, wherein the first motor is operatively connected to a first shaft of the three-flow gas turbine engine and the second motor is operatively connected to a second shaft of the three-flow gas turbine engine.

Claims

1. A method for generating electricity using an electric motor, characterized in that, The method includes: Under the operating conditions of a gas turbine engine, the rotor of the electric motor rotates relative to the stator of the electric motor and together with the shaft of the gas turbine engine. The gas turbine engine is a three-flow gas turbine engine with a defined axial direction. The three-flow gas turbine engine includes: the shaft, a main fan operably connected to the shaft, an intermediate fan located downstream of the main fan and operably connected to the shaft, and a low-pressure turbine operably connected to the shaft. Rotating the rotor of the motor relative to the stator of the motor includes generating motor power and generating low-pressure turbine power under the operating conditions, wherein the ratio of the motor power to the low-pressure turbine power is greater than 0.1 and less than 1.

0.

2. The method according to claim 1, characterized in that, The operating conditions mentioned above are flight idling operating conditions.

3. The method according to claim 1, characterized in that, The generation of the motor power under the operating conditions includes generating the motor power in kilowatts under the operating conditions, and the generation of the low-pressure turbine power under the operating conditions includes generating the low-pressure turbine power in horsepower under the operating conditions.

4. The method according to claim 1, characterized in that, The rotation of the rotor of the motor relative to the stator of the motor further includes, under the operating conditions, the motor generating an electrical output from 100 kW to 3000 kW and a voltage in DC volts from 270 DC volts to 3000 DC volts.

5. The method according to claim 4, characterized in that, Under the operating conditions, the power-to-voltage ratio of the motor is equal to or greater than 0.3 and less than or equal to 2.

0.

6. The method according to claim 1, characterized in that, The main fan includes a plurality of fan blades, the intermediate fan has a plurality of intermediate fan blades, and the three-flow gas turbine engine defines the ratio of the main fan radius to the intermediate fan radius as equal to or greater than 2.0 and less than or equal to 6.5, the ratio being defined by a radius spanning the longitudinal axis defined by the three-flow gas turbine engine and between the leading edge tip of one of the fan blades and the radius spanning the longitudinal axis and between the leading edge tip of one of the intermediate fan blades.

7. The method according to claim 1, characterized in that, The three-flow gas turbine engine further defines the ratio of the motor tip radius to the low-pressure turbine last-stage hub radius as equal to or greater than 0.1 and less than or equal to 1.0, the ratio being defined by the radius between the longitudinal axis defined by the three-flow gas turbine engine and the outermost point of the rotor of the motor, and the radius between the longitudinal axis and the outermost point of the hub of the last-stage turbine blade of the low-pressure turbine.

8. The method according to claim 1, characterized in that, The gas turbine engine further includes: Engine core; Core cover, the core cover surrounding the engine core; A core conduit, defined between the engine core and the core cover; A fan shroud surrounding the core shroud; Fan duct, the fan duct being defined between the core shroud and the fan shroud; and An inlet pipe is in flow communication with the core pipe and the fan pipe, the inlet pipe is defined between the engine core and the fan shroud, and the intermediate fan is positioned within the inlet pipe.

9. The method according to claim 1, characterized in that, The three-flow gas turbine engine defines a radial direction, and the three-flow gas turbine engine further includes: Engine core; Core cover, the core cover surrounding the engine core; A core conduit, defined between the engine core and the core cover; A fan shroud surrounding the core shroud; Fan duct, the fan duct being defined between the core shroud and the fan shroud; and An inlet pipe is in flow communication with the core pipe and the fan pipe, the inlet pipe is defined between the engine core and the fan shroud, and the motor is directly mechanically connected to the shaft and positioned inside the core pipe along the radial direction.

10. An electric motor for a gas turbine engine, characterized in that, The motor includes: Stator; and A rotor, rotatable relative to the stator to generate motor power under operating conditions of the gas turbine engine, wherein the gas turbine engine is a three-flow gas turbine engine defining an axial direction and includes: a shaft operably coupled to the rotor of the motor; a main fan operably coupled to the shaft; an intermediate fan positioned downstream of the main fan and operably coupled to the shaft; and a low-pressure turbine operably coupled to the shaft, wherein when the motor generates the motor power, the low-pressure turbine generates low-pressure turbine power, and wherein the ratio of the motor power to the low-pressure turbine power is greater than 0.1 and less than 1.

0.

11. The motor according to claim 10, characterized in that, The power of the motor is measured in kilowatts, and the power of the low-pressure turbine is measured in horsepower.

12. The motor according to claim 10, characterized in that, When generating the motor power, the motor is configured to provide a power output from 100 kW to 3000 kW and a voltage in DC volts from 270 DC volts to 3000 DC volts under the operating conditions.

13. The motor according to claim 12, characterized in that, Under the operating conditions, the power-to-voltage ratio of the motor is equal to or greater than 0.3 and less than or equal to 2.

0.

14. A three-flow gas turbine engine, characterized in that, include: axis; A main fan, which is operably connected to the shaft; An intermediate fan, positioned downstream of the main fan and operably connected to the shaft, the intermediate fan having intermediate fan blades; Low-pressure turbine; and An electric motor operably connected to the shaft, the motor having a stator and a rotor, the rotor being capable of rotating together with the shaft; When the motor generates the motor power, the low-pressure turbine generates the low-pressure turbine power, and the ratio of the motor power to the low-pressure turbine power is greater than 0.1 and less than 1.

0.

15. The three-flow gas turbine engine according to claim 14, characterized in that, The power of the motor is measured in kilowatts, and the power of the low-pressure turbine is measured in horsepower.

16. The three-flow gas turbine engine according to claim 14, characterized in that, When generating the motor power, the motor is configured to provide a power output from 100 kW to 3000 kW and a voltage in DC volts from 270 DC volts to 3000 DC volts under the operating conditions.

17. The three-flow gas turbine engine according to claim 16, characterized in that, Under the operating conditions, the power-to-voltage ratio of the motor is equal to or greater than 0.3 and less than or equal to 2.

0.

18. The three-flow gas turbine engine according to claim 14, characterized in that, The three-flow gas turbine engine further defines the ratio of the motor tip radius to the low-pressure turbine last stage hub radius as equal to or greater than 0.1 and less than or equal to 1.

0.

19. The three-flow gas turbine engine according to claim 14, characterized in that, The three-flow gas turbine engine defines an axial direction, and the three-flow gas turbine engine defines a motor length to low-pressure turbine length ratio equal to or greater than 0.01 and less than or equal to 3.0, the motor length to low-pressure turbine length ratio being defined by the length of the low-pressure turbine and the length of the motor, the length of the motor spanning along the axial direction between the leading and trailing edges of the rotor of the motor, and the length of the low-pressure turbine spanning between the leading edge of the hub of the first-stage turbine blade of the low-pressure turbine and the trailing edge of the hub of the last-stage turbine blade of the low-pressure turbine.

20. The three-flow gas turbine engine according to claim 14, characterized in that, The operating conditions mentioned above are flight idling operating conditions.

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