# US 12,006,055 B2 · Gas turbine engine with electric machines

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- Number: US 12,006,055 B2
- Document ID: US12006055B2
- Status: Granted
- Kind: B2
- Application number: 17/940,030
- Filed: 2022-09-08
- Published: 2023-07-13
- Granted: 2024-06-11
- Earliest claimed: 2021-09-08
- Assignees: ROLLS-ROYCE plc
- Applicants: ROLLS-ROYCE plc
- Inventors: Benjamin J Sellers; Andrew J Newman; Gordon Margary; Paul R Davies; Stephen J Bradbrook
- Web page: https://patentgrep.com/patent/US12006055B2

## CPC

- B64D 33/08: of power plant cooling systems
- F02C 7/18: the medium being gaseous, e.g. air {(F02C7/125 takes precedence)}
- F02K 3/06: with front fan
- F02K 3/105: Heating the by-pass flow
- F02K 5/00: Plants including an engine, other than a gas turbine, driving a compressor or a ducted fan
- B64D 27/026: {comprising different types of power plants, e.g. combination of a piston engine and a gas-turbine (Hybrid electric aircraft B64D27/33)}
- F05D 2220/76: an electrical generator
- F05D 2260/213: by the provision of a heat exchanger within the cooling circuit
- Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft
- B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00)
- F02K: JET-PROPULSION PLANTS (features of jet-propulsion plants common to gas-turbine plants, air intakes or fuel supply control of air-breathing jet-propulsion plants F02C7/00, F02C9/00)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A cooling system for an aircraft comprises a gas turbine engine, an ancillary apparatus, and a heat exchanger. The gas turbine engine comprises, in axial flow sequence, a compressor module, a combustor module, and a turbine module, with a first electric machine being rotationally connected to the turbine module. The first electrical machine is configured to generate an electrical power PEM1 (W). The heat exchanger is configured to transfer a total waste heat energy Q (W) generated by the gas turbine engine and the ancillary apparatus, to an airflow passing through the heat exchanger, and a ratio S of: S = ( Total ⁢ Electrical ⁢ Power ⁢ Generated = P EM ⁢ 1 ) ( Total ⁢ Heat ⁢ Energy ⁢ Rejected ⁢ to ⁢ Airflow = Q ) is in a range of between 0.50 and 5.00.

## Claims

### Claim 1

A cooling system for an aircraft, the cooling system comprising a gas turbine engine, an ancillary apparatus, and a heat exchanger, the gas turbine engine comprising, in axial flow sequence, the heat exchanger, a compressor module, a combustor module, and a turbine module, and a first electric machine being rotationally connected to the turbine module, the first electrical machine being configured to generate an electrical power PEM1 (W),
the heat exchanger being configured to transfer a total waste heat energy Q (W) generated by the gas turbine engine and the ancillary apparatus, to an airflow passing through the heat exchanger and through a duct towards a fan where the airflow separates into a core engine flow and a bypass flow downstream of the fan, wherein the duct is elongated and positioned upstream of the fan, and the heat exchanger comprises a plurality of heat transfer elements extending radially outwardly from a central hub along an axis of rotation of the gas turbine engine, and
wherein, when the gas turbine engine is operating at a full power condition at Sea Level Static conditions and in an International Standard Atmosphere of 15° C. and 1,013.25 mb, a ratio S of:
(
Total
⁢
Electrical
⁢
Power
⁢
Generated
=
P
EM
⁢
1
)
(
Total
⁢
Heat
⁢
Energy
⁢
Rejected
⁢
to
⁢
Airflow
=
Q
)
is between 0.50 and 5.00.

### Claim 2 (depends on 1)

The cooling system as claimed in claim 1, wherein the gas turbine engine is a turbofan engine comprising, in axial flow sequence, a fan assembly, the compressor module, the combustor module, and the turbine module.

### Claim 3 (depends on 2)

The cooling system as claimed in claim 2, the fan assembly comprising a plurality of fan blades extending radially from a hub, the plurality of fan blades defining a fan diameter, and wherein the fan diameter is 0.3 m to 1.4 m.

### Claim 4 (depends on 2)

The cooling system as claimed in claim 2, further comprising a second electric machine rotationally connected to the fan assembly, the second electrical machine being configured to generate an electrical power PEM2 (watts), and
wherein, a ratio S of:
S
=
(
Total
⁢
Electrical
⁢
Power
⁢
Generated
=
P
EM
⁢
1
)
(
Total
⁢
Heat
⁢
Energy
⁢
Rejected
⁢
to
⁢
Airflow
=
Q
)
is between 0.50 and 8.00.

### Claim 5 (depends on 2)

The cooling system as claimed in claim 2, wherein the first electric machine is positioned axially between the fan assembly and the compressor module.

### Claim 6 (depends on 2)

The cooling system as claimed in claim 2, the gas turbine engine further comprising an outer casing, the outer casing enclosing the sequential arrangement of the compressor module, the combustor module, and the turbine module, an annular bypass duct being defined between the outer casing and the sequential arrangement of modules, a bypass ratio being defined as a ratio of a mass air flow rate through the bypass duct to a mass air flow rate through the sequential arrangement of modules, and wherein the bypass ratio is less than 4.0.

### Claim 7 (depends on 4)

The cooling system as claimed in claim 4, wherein at least one of the first electric machine and the second electric machine, comprises an axial length a diameter, and wherein a ratio of the axial length to the diameter for the respective electric machine is in a range between 0.5 to 2.0.

### Claim 8 (depends on 2)

The cooling system as claimed in claim 2, wherein the fan assembly has two or more fan stages, at least one of the fan stages comprising a plurality of fan blades defining a fan diameter.

### Claim 9 (depends on 1)

An aircraft comprising the cooling system as claimed in claim 1.

### Claim 10

A method of operating a cooling system for an aircraft, the method comprising:
providing a gas turbine engine and an ancillary apparatus, the gas turbine engine comprising, in axial flow sequence, a heat exchanger, a compressor module, a combustor module, and a turbine module, and a first electric machine that is rotationally connected to the turbine module;
providing the heat exchanger that is capable of transferring a total waste heat energy Q (W) generated by the gas turbine engine and the ancillary apparatus, to an airflow passing through the heat exchanger and through a duct towards a fan where the airflow separates into a core engine flow and a bypass flow downstream of a fan, wherein the duct is elongated and positioned upstream of the fan, and the heat exchanger comprises a plurality of heat transfer elements extending radially outwardly from a central hub along an axis of rotation of the gas turbine engine; and
operating the gas turbine engine at a full power condition at Sea Level Static conditions and in an International Standard Atmosphere of 15° C. and 1,013.25 mb in which the gas turbine engine generates a total waste heat energy quantity Q (W), and the first electric machine generates an electrical power PEM1 (W), and where a ratio of:
(
Total
⁢
Electrical
⁢
Power
⁢
Generated
=
P
EM
⁢
1
+
P
EM
⁢
2
)
(
Total
⁢
Heat
⁢
Energy
⁢
Rejected
⁢
to
⁢
Airflow
=
Q
)
is between 0.50 and 5.00.

### Claim 11 (depends on 10)

The method as claimed in claim 10, wherein
the gas turbine engine is a turbofan gas turbine engine, the turbofan gas turbine engine comprising, in axial flow sequence, a fan assembly, the compressor module, the combustor module, and the turbine module, and the first electric machine; and
further comprising
providing a second electric machine rotationally connected to the fan assembly;
operating the turbofan gas turbine engine at the full power condition in which the second electric machine generates an electrical power PEM2 (W), and where a ratio of:
S
=
(
Total
⁢
Electrical
⁢
Power
⁢
Generated
=
P
EM
⁢
1
+
P
EM
⁢
2
)
(
Total
⁢
Heat
⁢
Energy
⁢
Rejected
⁢
to
⁢
Airflow
=
Q
)
is between 0.50 and 8.00.

### Claim 12 (depends on 2)

The cooling system as claimed in claim 2, the fan assembly comprising a plurality of fan blades extending radially from a hub, the plurality of fan blades defining a fan diameter, and wherein the fan diameter is within 0.4 m to 1.2 m.

### Claim 13 (depends on 2)

The cooling system as claimed in claim 2, the fan assembly comprising a plurality of fan blades extending radially from a hub, the plurality of fan blades defining a fan diameter, and wherein the fan diameter is within 0.7 m to 1.0 m.