GAS TURBINE ENGINE WITH AN ELECTROMAGNETIC TRANSMISSION

Abstract

A gas turbine engine, in particular for an airplane, includes a bladed rotor, a shaft driven by a turbine and an electrical generator including first and second generator components that can be rotated and magnetically coupled to one another, the first one being fixed to the shaft and the second one being mechanically coupled to the bladed rotor so as to drive the bladed rotor.

Claims

1. A gas turbine engine, in particular for an airplane, comprising: a bladed rotor, a shaft driven by a turbine and an electrical generator including first and second generator components that can be rotated and magnetically coupled to one another, the first one being fixed to the shaft and the second one being mechanically coupled to the bladed rotor so as to drive the bladed rotor.

2. The gas turbine engine according to claim 1, wherein the second generator component is fixed to the bladed rotor.

3. The gas turbine engine according to claim 1, wherein the first generator component is a generator rotor and the second generator component is a generator stator.

4. The gas turbine engine according to claim 1, further comprising an electric motor for driving the bladed rotor.

5. The gas turbine engine according to claim 4, wherein the bladed rotor is arranged between the electrical motor and the electrical generator.

6. The gas turbine engine according to claim 4, wherein the electrical motor is arranged between the bladed rotor and the electrical generator.

7. The gas turbine engine according to claim 4, wherein the electric motor and the bladed rotor are coupled with one another via an epicyclic gearing.

8. The gas turbine engine according to claim 7, wherein the epicyclic gearing is arranged between the bladed rotor and the electrical motor.

9. The gas turbine engine according to claim 4, wherein the electrical generator is configured to provide electrical power to the electric motor.

10. The gas turbine engine according to claim 4, further comprising a frequency converter coupling the electrical generator with the electric motor.

11. The gas turbine engine according to claim 4, further comprising an electrical energy storage to store electrical power and provide electrical power to the electric motor.

12. The gas turbine engine according to claim 11, wherein the energy storage comprises at least one of a battery and a supercapacitor.

13. The gas turbine engine according to claim 11, wherein the energy storage is coupled to at least one of the electrical generator, a solar panel and a thermoelectric generator to receive electrical energy from the at least one of the electrical generator, the solar panel and the thermoelectric generator.

14. The gas turbine engine according to claim 1, wherein the bladed rotor is a fan.

15. An airplane comprising at least one gas turbine engine according to claim 1.

16. A method for operating the gas turbine engine according to claim 1, the method comprising magnetically transmitting torque by means of the electrical generator.

17. The method according claim 16, the method further comprising magnetizing the electrical generator in dependence of a current operating status of the gas turbine engine, wherein the current operating status is one of engine start, take-off, cruise and landing.

18. The method according claim 16, wherein the gas turbine engine further comprises an electric motor for driving the bladed rotor, wherein the method further comprises providing electrical power to the electric motor in dependence on the current operating status of the gas turbine engine.

Description

[0051] Embodiments will now be described by way of example only, with reference to the Figures, in which:

[0052] FIG. 1 is a perspective view of an aircraft having a plurality of gas turbine engines;

[0053] FIG. 2 is a sectional side view of a gas turbine engine;

[0054] FIG. 3 is a schematic side view of a portion of a gas turbine engine having a fan driven via an electromagnetic transmission gear and an electric motor coupled to a planet carrier of an epicyclic gearing;

[0055] FIG. 4 is a schematic side view of a portion of a gas turbine engine having a fan driven via an electromagnetic transmission gear and an electric motor coupled to a sun gear of an epicyclic gearing;

[0056] FIG. 5 is a schematic side view of a portion of a gas turbine engine having a fan driven via an electromagnetic transmission gear and an electric motor arranged between the fan and the electromagnetic transmission gear; and

[0057] FIG. 6 is a method for controlling a gas turbine engine.

[0058] FIG. 1 shows an aircraft 8 in the form of a passenger aircraft. Aircraft 8 comprises several (i.e., two) gas turbine engines 10. The gas turbine engines 10 will be described in more detail below with particular reference to FIG. 2. One or more of the gas turbine engines 10 comprise an electromagnetic transmission gear, in particular in accordance with any one of FIGS. 3 to 5.

[0059] FIG. 2 illustrates a gas turbine engine 10 of the aircraft 8. The gas turbine engine 10 is an aero engine. The gas turbine engine 10 has a principal rotational axis 9. The engine 10 comprises an air intake 12 and a propulsive fan 23 (a bladed rotor) that generates two airflows: a core airflow A and a bypass airflow B. The gas turbine engine 10 comprises a core 11 that receives the core airflow A. The engine core 11 comprises, in axial flow series, a low pressure compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, a low pressure turbine 19 and a core exhaust nozzle 20. A nacelle 21 surrounds the gas turbine engine 10 and defines a bypass duct 22 and a bypass exhaust nozzle 18. The bypass airflow B flows through the bypass duct 22. The fan 23 is driven by the low pressure turbine 19 via a shaft 26 (low-pressure shaft) and an electromagnetic transmission gear comprising an electrical generator 30.

[0060] In use, the core airflow A is accelerated and compressed by the low pressure compressor 14 and directed into the high pressure compressor 15 where further compression takes place. The compressed air exhausted from the high pressure compressor 15 is directed into the combustion equipment 16 where it is mixed with fuel and the mixture is combusted. The resultant hot combustion products then expand through, and thereby drive, the high pressure and low pressure turbines 17, 19 before being exhausted through the nozzle 20 to provide some propulsive thrust. The high pressure turbine 17 drives the high pressure compressor 15 by a suitable interconnecting shaft 27 (high-pressure shaft). The fan 23 generally provides the majority of the propulsive thrust.

[0061] FIG. 3 shows an arrangement for the gas turbine engine 10 according to FIG. 2. According to an embodiment, the gas turbine engine 10 of FIG. 2 comprises the arrangement of FIG. 3.

[0062] FIG. 3 schematically shows the low-pressure turbine 19 being fixedly connected to the (low-pressure) shaft 26. The shaft 26 is driven by the low-pressure turbine 19.

[0063] The shaft 26 is coupled to an electrical generator 30. The electrical generator 30 comprises a generator rotor 31 as a first generator component and a generator stator 32 as a second generator component. The generator rotor 31 is rotatable relative to the generator stator 32. The generator rotor 31 and the generator stator 32 are or can be magnetically coupled to one another. The generator stator 32 surrounds the generator rotor 31. The generator rotor 31 is accommodated within the generator stator

[0064] The generator stator 32 is fixedly connected with the fan 23 (the bladed rotor), in the present example by means of a link 33.

[0065] One of the generator stator 32 and the generator rotor 31 comprises an armature for producing electrical power. The other one of the generator stator 32 and the generator rotor 31 comprises a field winding and/or at least one permanent magnet.

[0066] The electrical generator 30 is an alternator. In alternative embodiments the electrical generator may be a dynamo.

[0067] Both the generator rotor 31 and the generator stator 32 are rotatable with respect to the support structure of the gas turbine engine 10 (e.g., the nacelle 21).

[0068] Via the electrical generator 30 the shaft 26 may transmit (in use: transmits) torque to the fan 23 (e.g., depending on a magnetization of the field winding). The electrical generator 30 thus works as a magnetic coupling. In view of the electromagnetic nature of this coupling, the electrical generator 30 may also be referred to as an electromagnetic transmission.

[0069] In addition, the electrical generator 30 may produce electrical power due to a difference in relative movement between the generator stator 32 and the generator rotor 31. The fan 23 rotates at a lower speed than the shaft 26. Half of the shaft 23 torque is transferred to the fan 23. For example, the shaft 26 may rotate with 3000 rpm and the fan 23 may rotate at 1000 rpm (e.g., with respect to the nacelle 21 or another support structure such as support structure 24 shown in FIG. 2). As a result, the speed of the electrical generator 30 will be 2000 rpm. The speed of the electrical generator 30 is adjustable in dependence of the magnetization of the electrical generator 30 (e.g., the magnetization of the field winding). Also the load of the engine may be adjusted by the magnetization of the electrical generator 30. The torque transferred from the generator rotor 31 to the generator stator 32 is half of the shaft 26 torque.

[0070] Further, an electric motor 40 is provided. In the present example, the electric motor 40 is arranged in a nose cone 29 of the fan 23. The electric motor 40 comprises a housing that is fixed to a stationary support structure or the gas turbine engine 10. The electric motor 40 comprises an output shaft 41 rotatable with respect to the housing.

[0071] The electric motor 40 is coupled to the fan 23 so as to drive the fan 23. When the electric motor 40 is activated, the load in the electrical generator 30 and the and core engine can be reduced. In the example of FIG. 3, the electric motor 40 is coupled to the fan 23 by means of a reduction gearing. According to FIG. 3, the reduction gearing is an epicyclic gearing 50.

[0072] The epicyclic gearing 50 comprises a sun gear 51, a plurality of planet gears 32 and a ring gear 54. Each planet gear 52 is in engagement with the (inner) sun gear 51 and the (outer) ring gear 54. Each planet gear 52 is rotatably mounted on a planet carrier 53.

[0073] The output shaft 41 of the electric motor 40 is fixed to the planet carrier 53. An activation of the electric motor 40 rotates the planet carrier 53 with respect to the ring gear 54. By this, the planet gears 52 roll along the ring gear 54 and thereby rotate on the planet carrier 53. Thereby the sun gear 51 is rotated with respect to the ring gear 54. The ring gear 54 is fixed with respect to the support structure of the gas turbine engine 10.

[0074] The sun gear 51 of the epicyclic gearing 50 is fixed to the fan 23. In the example of FIG. 3, the sun gear 51 is fixed to the link 33.

[0075] An activation of the electric motor 40 exerts a torque on the fan 23. The electric motor 40 is adapted for driving the fan 23.

[0076] According to FIG. 3 (and seen in axial direction of the principal rotational axis 9), the epicyclic gearing 50 is arranged between (and adjacent to) the electric motor 40 and the fan 23. The fan 23 is arranged between (and adjacent to) the electrical generator 30 and the epicyclic gearing 50. Further, the fan 23 is arranged between the electric motor 40 and the electrical generator 30. The epicyclic gearing 50 is arranged between the electric motor 40 and the electrical generator 30.

[0077] A frequency converter 60 is electrically coupled to the electrical generator 30. The frequency converter 60 is adapted to receive input current with a frequency and to provide output current with the same or a different frequency. The frequency converter 60 may be adjustable so as to adjust the frequency of the output current. The frequency converter 60 is electrically coupled to the electric motor 40. The frequency converter 60 provides the output current to the electric motor 40.

[0078] Alternatively or in addition, electrical power from the electrical generator 30 may be supplied to another component (e.g. of the airplane 8) and/or for other purposes than to drive the electric motor 40. Then, one or more additional generators of the airplane 8 may be omitted.

[0079] An electrical energy storage 70 is provided to store electrical power and to provide the stored electrical power to the electric motor 40. The electrical energy storage 70 comprises one or more batteries and/or one or more supercapacitors. The electrical energy storage 70 may be electrically coupled to the electric motor 40 directly and/or by means of the frequency converter 60. The electrical power storage 70 may be charged by an electrical grid when available.

[0080] The electric motor 40 may receive electrical power from the electrical generator 30 and/or from the electrical power storage 70. Further, one or more thermoelectric generators 72 are provided. For example, the one or more thermoelectric generators 72 may be arranged adjacent to a turbine of the gas turbine engine, such as the low-pressure turbine 19. Since hot combustion gases enter the turbines 17, 19, the turbines 17, 19 and their surroundings are warmer than adjacent areas. Therefore, thermoelectric generators 72 (such as peltier elements) may use a temperature gradient to create electrical power. This power may be used to drive the electric motor 40.

[0081] Alternatively or in addition, the gas turbine engine 10 comprises one or more solar panels 71 (see FIG. 2). The one or more solar panels 71 are configured to provide electrical power to the electric motor 40.

[0082] FIG. 4 shows an arrangement similar to FIG. 3 for the gas turbine engine 10 according to FIG. 2. According to an embodiment, the gas turbine engine 10 of FIG. 2 comprises the arrangement of FIG. 4. In contrast to FIG. 3, however, the output shaft 41 of the electric motor 40 is fixed to the sun gear 51. The ring gear 54 is fixed to the support structure of the gas turbine engine 10. The planet carrier 53 is fixed to the fan 23.

[0083] FIG. 5 shows another arrangement for the gas turbine engine 10 according to FIG. 2. According to an embodiment, the gas turbine engine 10 of FIG. 2 comprises the arrangement of FIG. 5. According to FIG. 5, the epicyclic gearing 50 is arranged between (and adjacent to) the fan 23 and an electric motor 40. Further, the epicyclic gearing 50 is arranged between the fan 23 and the electrical generator 30.

[0084] The electric motor 40 is arranged between (and adjacent to) the epicyclic gearing 50 and the electrical generator 30. Further, the electric motor 40 is arranged between the fan 23 and the electrical generator 30.

[0085] The electric motor 40 is arranged coaxially with respect to the principal rotational axis 9 (see FIG. 2). The electric motor 40 comprises a stator 42 fixed with respect to the support structure of the gas turbine engine 10, and a rotor 43 fixedly connected to the planet carrier 53.

[0086] A link 33 fixedly connects the generator stator 32 with the fan 23. The link 33 extends through the electric motor 40. According to FIG. 5, the link 33 is rotatable with respect to the rotor 43 of the electric motor 40, i.e., the link 33 runs freely inside the electric motor 40. The sun gear 51 of the epicyclic gearing 50 is fixed to the link 33.

[0087] FIG. 6 shows a method for controlling the gas turbine engine 10. The method comprises:

[0088] Step S1: Magnetically transmitting torque from the low-pressure turbine 19 to the fan 23 by means of the electrical generator 30.

[0089] Step S2: Determining a current operating status of the gas turbine engine 10 and/or the aircraft 8 and magnetizing the electrical generator 30 (e.g., the field winding thereof) in dependence of the determined operating status. For example, the current operating status may be one of engine-start, take-off, cruise and landing.

[0090] Step S3: Providing electrical power to the electric motor 40; 40 in dependence on the current operating status of the gas turbine engine 10.

[0091] For example, when determining an engine-start, the electrical generator 30 may be magnetized. The generator magnetic field creates torque to the fan 23. The fan 23 then starts to rotate with a lower speed than the shaft 26. At the same time the electrical generator 30 starts to produce electrical power. The produces electrical power is provided to the electric motor 40; 40 to provide additional torque to the fan 23. Optional excess electrical power may be stored in the electrical energy storage 70.

[0092] As another example, when determining a take-off, energy stored in the electrical energy storage 70 is provided to the electric motor 40; 40, e.g. to produce maximum thrust.

[0093] As yet another example, when determining a cruise operation, the electrical energy storage 70 may be charged by the electrical generator 30. When the electrical energy storage 70 is fully charged, all power (mechanical and electrical) transmitted and generated by the electrical generator 30 is used to drive the fan 23. Optionally, additional electrical power from the one or more thermoelectric generators 72 and/or the one or more solar panels 71 may be provided to the electric motor 40; 40. The flow rate of fuel to the combustion equipment 16 may be correspondingly reduced.

[0094] As a further example, then determining a landing, the electrical power stored in the electrical energy storage 70 may be used to boost the fan 23 when necessary.

[0095] Thereby, the specific fuel consumption of the gas turbine engine 10 may be reduced.

[0096] Thus, by means of the electrical generator 30, power from the shaft 26 is transferred to the fan 23 partly via magnetic coupling and partly electrically by means of the electric motor 40; 40.

[0097] The aircraft 8 may comprise more than one gas turbine engine 10 according to FIG. 2. When a core engine of one of the gas turbine engines 10 fails, electrical power produced by the electrical generator 30 of the other gas turbine engine 10 may be provided to the electric motor 40; 40 of the gas turbine engine 10 with the failed core so as to rotate the fan 23 thereof and produce thrust.

[0098] Note that the terms low pressure turbine and low pressure compressor as used herein may be taken to mean the lowest pressure turbine stages and lowest pressure compressor stages (i.e. not including the fan 23) respectively and/or the turbine and compressor stages that are connected together by the interconnecting shaft 26 with the lowest rotational speed in the engine. In some literature, the low pressure turbine and low pressure compressor referred to herein may alternatively be known as the intermediate pressure turbine and intermediate pressure compressor. Where such alternative nomenclature is used, the fan 23 may be referred to as a first, or lowest pressure, compression stage.

[0099] It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.

LIST OF REFERENCE NUMBERS

[0100] 8 airplane

[0101] 9 principal rotational axis

[0102] 10 gas turbine engine

[0103] 11 engine core

[0104] 12 air intake

[0105] 14 low-pressure compressor

[0106] 15 high-pressure compressor

[0107] 16 combustion equipment

[0108] 17 high-pressure turbine

[0109] 18 bypass exhaust nozzle

[0110] 19 low-pressure turbine

[0111] 20 core exhaust nozzle

[0112] 21 nacelle (support structure)

[0113] 22 bypass duct

[0114] 23 propulsive fan (bladed rotor)

[0115] 24 support structure

[0116] 26 shaft

[0117] 27 shaft

[0118] 29 nose cone

[0119] 30 electrical generator

[0120] 31 generator rotor (first generator component)

[0121] 32 generator stator (second generator component)

[0122] 33; 33 link

[0123] 40; 40 electric motor

[0124] 41 output shaft

[0125] 42 stator

[0126] 43 rotor

[0127] 50 epicyclic gearing

[0128] 51 sun gear

[0129] 52 planet gear

[0130] 53 planet carrier

[0131] 54 ring gear

[0132] 60 frequency converter

[0133] 70 electrical energy storage

[0134] 71 solar panel

[0135] 72 thermoelectric generator

[0136] A core airflow

[0137] B bypass airflow