# US 12,180,899 B2 · Fuel delivery

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- Number: US 12,180,899 B2
- Document ID: US12180899B2
- Status: Granted
- Kind: B2
- Application number: 17/853,191
- Filed: 2022-06-29
- Published: 2023-10-12
- Granted: 2024-12-31
- Earliest claimed: 2022-04-12
- Assignees: ROLLS-ROYCE plc
- Applicants: ROLLS-ROYCE plc
- Inventors: Peter Swann; Craig W Bemment; Christopher P Madden
- Web page: https://patentgrep.com/patent/US12180899B2

## CPC

- F02C 9/26: Control of fuel supply (F02C9/48 takes precedence; fuel valves F02C7/232)
- F02C 9/40: specially adapted to the use of a special fuel or a plurality of fuels
- B64D 27/10: of gas-turbine type (jet aircraft B64D27/16)
- B64D 37/30: Fuel systems for specific fuels
- F02C 3/20: using a special fuel, oxidant, or dilution fluid to generate the combustion products
- F02C 7/22: Fuel supply systems
- F02C 9/28: Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed (F02C9/30 - F02C9/38, F02C9/44 take precedence)
- F23R 3/36: Supply of different fuels
- F05D 2220/323: for aircraft propulsion, e.g. jet engines
- F05D 2270/081: with as little smoke as possible
- F05D 2270/31: Fuel schedule for stage combustors
- 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)
- B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- F23R: GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY, e.g. GAS-TURBINE COMBUSTION CHAMBERS (fluidised bed combustion apparatus specially adapted for operation at superatmospheric pressures F23C10/16)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS

## Abstract

A gas turbine engine for an aircraft, including: staged combustion system having pilot fuel injectors and main fuel injectors, staged combustion system being operable in pilot-only range of operation and pilot-and-main range of operation; and fuel delivery regulator arranged to control delivery of fuel to pilot and main fuel injectors. Fuel delivery regulator arranged to receive fuel from a first fuel source containing a first fuel having a first fuel characteristic and a second fuel source containing a second fuel having a different second fuel characteristic. The fuel delivery regulator is arranged to deliver fuel to the pilot fuel injectors during at least part of the pilot-only range of operation having a different fuel characteristic from fuel delivered to one or both of the pilot and main fuel injectors during at least part of the pilot-and-main range of operation. A method of operating a gas turbine engine is also disclosed.

## Claims

### Claim 1

A gas turbine engine for an aircraft, comprising:
a staged combustion system having pilot fuel injectors and main fuel injectors, the staged combustion system being operable in a pilot-only range of operation and a pilot-and-main range of operation;
a fuel delivery regulator arranged to control delivery of fuel to the pilot and main fuel injectors, the fuel delivery regulator being arranged to receive fuel from a first fuel source containing a first fuel having a first fuel characteristic and a second fuel source containing a second fuel having a second fuel characteristic, the second fuel characteristic being different from the first fuel characteristic; and
an electronic engine controller configured to control the fuel delivery regulator, wherein
the fuel delivery regulator is arranged to deliver fuel to the pilot fuel injectors during at least part of the pilot-only range of operation having a different fuel characteristic from fuel delivered to one or both of the pilot and main fuel injectors during at least part of the pilot-and-main range of operation,
the first fuel is a sustainable aviation fuel (SAF), the first fuel characteristic is associated with a level of nonvolatile particulate matter (nvPM) production which is less than that of the second fuel characteristic, and the fuel delivered to the pilot fuel injectors during at least part of the pilot-only range of operation is associated with a level of nvPM production which is less than that of the fuel delivered to one or both of the pilot and main fuel injectors during at least part of the pilot-and-main range of operation,
the fuel delivery regulator is arranged to deliver fuel from the first fuel source to the pilot fuel injectors during operation in at least part of the pilot-only range of operation, and deliver fuel from the second fuel source to the pilot fuel injectors during the pilot-and-main range of operation,
the fuel delivery regulator is arranged to switch delivery of fuel to the pilot fuel injectors between fuel from the first fuel source and fuel from the second fuel source at one or more operating points within, or at a boundary of, the pilot-only range of operation, according to a mode signal from the electronic engine controller indicative of an operation range change of the staged combustion system,
the fuel delivery regulator is arranged to further switch delivery of fuel to the pilot fuel injectors between fuel from the first fuel source and fuel from the second fuel source at a threshold point within the pilot-only range of operation, and
the threshold point is:
a) a threshold fuel flow rate at which the production of nvPM by the gas turbine engine passes a threshold amount of the nvPM produced by the gas turbine engine during operation in which the pilot fuel injectors are delivered fuel having the second fuel characteristic; and/or
b) a predefined threshold fuel flow rate which is less than the fuel flow rate at the boundary between pilot-only operation and pilot-and-main operation by a predefined amount.

### Claim 2 (depends on 1)

A gas turbine engine according to claim 1, wherein the fuel delivery regulator is arranged to deliver fuel from the first fuel source to the pilot fuel injectors during operation in both the pilot-only and the pilot-and-main ranges of operation, and fuel from the second fuel source to the main fuel injectors during operation in the pilot-and-main range of operation.

### Claim 3 (depends on 1)

A gas turbine engine according to claim 1, wherein:
the fuel delivery regulator comprises a fuel blender arranged to receive a supply of fuel from both the first and second fuel sources and output fuel from the first fuel source, fuel from the second fuel source, or a blend thereof; and
the fuel blender is arranged to deliver fuel to the pilot fuel injectors.

### Claim 4 (depends on 3)

A gas turbine engine according to claim 3, wherein the fuel blender is arranged to deliver the blend of fuel from the first fuel source and fuel from the second fuel source to the pilot fuel injectors during at least part of the pilot-only range of operation.

### Claim 5 (depends on 4)

A gas turbine engine according to claim 4, wherein the fuel blender is arranged to deliver a blend of fuel to the pilot fuel injectors having a varying blend ratio of fuel from the first fuel source and fuel from the second fuel source, wherein the blend ratio is varied within the pilot-only range of operation according to the fuel flow rate.

### Claim 6 (depends on 5)

A gas turbine engine according to claim 5, wherein the dependence on fuel flow rate of the proportion of fuel from the first fuel source compared to that from the second fuel source is determined according to a desired resultant level of nvPM at a particular fuel flow rate, and may be determined such that the nvPM does not exceed a predetermined threshold or such that the nvPM production is minimised over a period of operation of the gas turbine engine.

### Claim 7 (depends on 5)

A gas turbine engine according to claim 5, wherein the fuel blender is arranged to blend fuel in order to achieve a desired level of nvPM at one or more operating conditions of the gas turbine engine within the pilot-only range of operation.

### Claim 8 (depends on 1)

A gas turbine engine according to claim 1, wherein the fuel regulator is arranged to deliver fuel to the pilot fuel injectors in order to minimise a cost function dependent on one or more nvPM impact parameters, wherein the one or more nvPM impact parameters optionally include any one or more of:
i) height above ground level at which the nvPM production takes place;
ii) location of the nvPM production;
iii) weather and/or atmospheric conditions at a location of the nvPM production;
iv) climate impacts associated with location of the nvPM production;
v) mass and/or size of individual nvPM particles produced;
vi) potential contrail production and/or contrail characteristics;
vii) local air quality (LAQ) impact of nvPM production; and/or
viii) nvPM mass and/or number.

### Claim 9 (depends on 5)

A gas turbine engine according to claim 5, wherein the blend ratio provided by the fuel blender is determined at least partly according to any one or more of:
a) the amount of fuel having the first fuel composition available for a proposed flight;
b) the amount of total fuel requirement for the pilot fuel injectors during pilot-only operation for the entire flight in a range of operation in which fuel is provided from the first fuel source; and/or
c) a fuel composition limit parameter.

### Claim 10

A method of operating a gas turbine engine for an aircraft, the gas turbine engine comprising a staged combustion system having pilot fuel injectors and main fuel injectors, the staged combustion system being operable in a pilot-only range of operation and a pilot-and-main range of operation, the method comprising:
regulating fuel delivery to the pilot and main fuel injectors from a first fuel source containing a first fuel having a first fuel characteristic and a second fuel source containing a second fuel having a second fuel characteristic, the second fuel characteristic being different from the first fuel characteristic, wherein
the regulating of the fuel delivery comprises delivering fuel to the pilot fuel injectors during at least part of the pilot-only range of operation having a different fuel characteristic from fuel delivered to one or both of the pilot and main fuel injectors during at least part of the pilot-and-main range of operation,
the first fuel is a sustainable aviation fuel (SAF), the first fuel characteristic is associated with a level of nonvolatile particulate matter (nvPM) production which is less than that of the second fuel characteristic, and the fuel delivered to the pilot fuel injectors during at least part of the pilot-only range of operation is associated with a level of nvPM production which is less than that of the fuel delivered to one or both of the pilot and main fuel injectors during at least part of the pilot-and-main range of operation,
the regulating of the fuel delivery comprises delivering fuel from the first fuel source to the pilot fuel injectors during operation in at least part of the pilot-only range of operation, and delivering fuel from the second fuel source to the pilot fuel injectors during the pilot-and-main range of operation
the regulating of the fuel delivery comprises switching delivery of fuel to the pilot fuel injectors between fuel from the first fuel source and fuel from the second fuel source at one or more operating points within, or at a boundary of, the pilot-only range of operation, according to a mode signal from an electronic engine controller indicative of an operation range change of the staged combustion system,
the regulating of the fuel delivery further comprises switching delivery of fuel to the pilot fuel injectors between fuel from the first fuel source and fuel from the second fuel source at a threshold point within the pilot-only range of operation, and
the threshold point is:
a) a threshold fuel flow rate at which the production of nvPM by the gas turbine engine passes a threshold amount of the nvPM produced by the gas turbine engine during operation in which the pilot fuel injectors are delivered fuel having the second fuel characteristic; and/or
b) a predefined threshold fuel flow rate which is less than the fuel flow rate at the boundary between pilot-only operation and pilot-and-main operation by a predefined amount.

### Claim 11 (depends on 10)

A method according to claim 10, wherein the regulating of the fuel delivery comprises delivering fuel from the first fuel source to the pilot fuel injectors during operation in both the pilot-only and the pilot-and-main ranges of operation, and fuel from the second fuel source to the main fuel injectors during operation in the pilot-and-main range of operation.

### Claim 12 (depends on 10)

A method according to claim 10, wherein the regulating of the fuel delivery comprises:
blending a supply of fuel from both the first and second fuel sources to form a blended fuel consisting of fuel from the first fuel source, fuel from the second fuel source, or a blend thereof; and
delivering the blended fuel to the pilot fuel injectors.

### Claim 13

A gas turbine engine for an aircraft, comprising:
a staged combustion system having pilot fuel injectors and main fuel injectors, the staged combustion system being operable in a pilot-only range of operation and a pilot-and-main range of operation;
a fuel delivery regulator arranged to control delivery of fuel to the pilot and main fuel injectors, the fuel delivery regulator being arranged to receive fuel from a first fuel source containing a first fuel having a first fuel characteristic and a second fuel source containing a second fuel having a second fuel characteristic, the second fuel characteristic being different from the first fuel characteristic; and
an electronic engine controller configured to control the fuel delivery regulator, wherein
the fuel delivery regulator is arranged to deliver fuel to the pilot fuel injectors during at least part of the pilot-only range of operation having a different fuel characteristic from fuel delivered to one or both of the pilot and main fuel injectors during at least part of the pilot-and-main range of operation,
the first fuel is a sustainable aviation fuel (SAF), the first fuel characteristic is associated with a level of nonvolatile particulate matter (nvPM) production which is less than that of the second fuel characteristic, and the fuel delivered to the pilot fuel injectors during at least part of the pilot-only range of operation is associated with a level of nvPM production which is less than that of the fuel delivered to one or both of the pilot and main fuel injectors during at least part of the pilot-and-main range of operation,
the fuel delivery regulator is arranged to deliver fuel from the first fuel source to the pilot fuel injectors during operation in at least part of the pilot-only range of operation, and deliver fuel from the second fuel source to the pilot fuel injectors during the pilot-and-main range of operation,
the fuel delivery regulator is arranged to switch delivery of fuel to the pilot fuel injectors between fuel from the first fuel source and fuel from the second fuel source at one or more operating points within, or at a boundary of, the pilot-only range of operation, according to a mode signal from the electronic engine controller indicative of an operation range change of the staged combustion system,
the fuel delivery regulator comprises a fuel blender arranged to receive a supply of fuel from both the first and second fuel sources and output fuel from the first fuel source, fuel from the second fuel source, or a blend thereof,
the fuel blender is arranged to deliver fuel to the pilot fuel injectors, and
the fuel blender is arranged to deliver the blend of fuel from the first fuel source and fuel from the second fuel source to the pilot fuel injectors during at least part of the pilot-only range of operation.