# US 11,898,489 B2 · Compression in a gas turbine engine

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- Number: US 11,898,489 B2
- Document ID: US11898489B2
- Status: Granted
- Kind: B2
- Application number: 18/123,091
- Filed: 2023-03-17
- Published: 2023-07-20
- Granted: 2024-02-13
- Earliest claimed: 2019-06-24
- Assignees: ROLLS-ROYCE plc
- Applicants: ROLLS-ROYCE plc
- Inventors: Craig W Bemment; Pascal Dunning
- Web page: https://patentgrep.com/patent/US11898489B2

## CPC

- F02C 3/04: having a turbine driving a compressor (power transmission arrangements F02C7/36; control of working fluid flow F02C9/16)
- F02C 3/107: with two or more rotors connected by power transmission
- F02C 7/36: Power transmission arrangements between the different shafts of the gas turbine plant, or between the gas-turbine plant and the power user ({F02C3/107 - F02C3/13 and} F02C7/32 take precedence; couplings for transmitting rotation F16D; gearing in general F16H)
- F02K 3/06: with front fan
- F05D 2200/14: Division
- F05D 2220/323: for aircraft propulsion, e.g. jet engines
- F05D 2220/36: specially adapted for the fan of turbofan engines
- F05D 2240/307: related to the tip of a rotor blade
- F05D 2260/4031: as in toothed gearing
- F05D 2260/40311: of the epicyclical, planetary or differential type
- Y02T 50/60: Efficient propulsion technologies, e.g. for 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 gas turbine engine for an aircraft comprises an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor, wherein a compressor exit temperature is defined as an average temperature of airflow at the exit from the compressor; and a fan located upstream of the engine core, the fan comprising a plurality of fan blades extending from a hub, each fan blade having a leading edge and a trailing edge, wherein a fan rotor entry temperature is defined as an average temperature of airflow across the leading edge of each fan blade at cruise conditions and a fan tip rotor exit temperature is defined as an average temperature of airflow across a radially outer portion of each fan blade at the trailing edge at cruise conditions. A core to fan tip temperature rise ratio is in the range from 2.845 to 3.8.

## Claims

### Claim 1

A gas turbine engine for an aircraft comprising:
an engine core comprising a turbine, a compressor, and a core shaft connecting the turbine to the compressor, wherein a compressor exit temperature is defined as an average temperature of airflow at the exit from the compressor at cruise conditions and a core entry temperature is defined as an average temperature of airflow entering the engine core at cruise conditions, and a core compressor temperature rise is defined as:
the
⁢
compressor
⁢
exit
⁢
temperature
the
⁢
core
⁢
entry
⁢
temperature
;
the engine core further comprising an annular splitter at which the flow is divided between a core flow that flows through the engine core, and a bypass flow that flows along a bypass duct, wherein stagnation streamlines around the circumference of the engine, stagnating on a leading edge of the annular splitter, form a streamsurface forming a radially inner boundary of a streamtube that contains all of the bypass flow; and
a fan located upstream of the engine core, the fan comprising a plurality of fan blades extending from a hub, each fan blade having a leading edge and a trailing edge, each fan blade having a radially outer portion lying within the streamtube that contains the bypass flow, and wherein a fan rotor entry temperature is defined as an average temperature of airflow across the leading edge of each fan blade at cruise conditions and a fan tip rotor exit temperature is defined as an average temperature of airflow across the radially outer portion of each fan blade at the trailing edge at cruise conditions and a fan tip temperature rise is defined as:
the
⁢
fan
⁢
tip
⁢
rotor
⁢
exit
⁢
temperature
the
⁢
fan
⁢
rotor
⁢
entry
⁢
temperature
,
and wherein the gas turbine engine is configured to have a core compressor to fan tip temperature rise ratio of:
the
⁢
core
⁢
compressor
⁢
temperature
⁢
rise
the
⁢
fan
⁢
tip
⁢
temperature
⁢
rise
in the range from 2.67 to 3.8,
the compressor exit temperature in the range of from 750 K to 1050 K, and
wherein the cruise conditions means the conditions at mid-cruise of the aircraft to which the gas turbine engine is attached, and the cruise conditions at mid-cruise means the conditions experienced by the aircraft and the gas turbine engine at a point between top of climb and start of descent at which 50% of the total fuel that is burned between the top of climb and the start of descent has been burned.

### Claim 2 (depends on 1)

The gas turbine engine according to claim 1, wherein the core compressor to fan tip temperature rise ratio is in the range from 2.67 to 3.7.

### Claim 3 (depends on 1)

The gas turbine engine according to claim 1, wherein the core compressor to fan tip temperature rise ratio is in the range from 2.80 to 2.95.

### Claim 4 (depends on 1)

The gas turbine engine according to claim 1, wherein the compressor exit temperature in the range of from 780 K to 1000 K.

### Claim 5 (depends on 1)

The gas turbine engine according to claim 1, wherein the core compressor temperature rise is in the range from 2.9 to 4.0.

### Claim 6 (depends on 1)

The gas turbine engine according to claim 1, wherein the core compressor temperature rise is in the range from 3.1 to 3.3.

### Claim 7 (depends on 1)

The gas turbine engine according to claim 1, wherein the engine comprises more than one compressor, and wherein the compressor exit temperature is measured at the exit from the highest pressure compressor.

### Claim 8 (depends on 1)

The gas turbine engine according claim 1, wherein a fan tip radius of the fan is defined between a centreline of the engine and an outermost tip of each fan blade at its leading edge and a fan hub radius of the fan is defined between the centreline of the engine and an outer surface of the hub at the radial position of the leading edge of each fan blade, wherein a fan hub to tip ratio of:
the
⁢
fan
⁢
hub
⁢
radius
the
⁢
fan
⁢
tip
⁢
radius
is in the range from 0.2 to 0.285.

### Claim 9 (depends on 1)

The gas turbine engine according to claim 1, wherein a specific thrust of the engine at cruise conditions, defined as net engine thrust divided by mass flow rate through the engine, is in the range from 50 to 100 Nkg−1s.

### Claim 10 (depends on 1)

The gas turbine engine according to claim 1, wherein the fan tip temperature rise is in the range from 1.05 to 1.11.

### Claim 11 (depends on 1)

The gas turbine engine according to claim 1, wherein a fan root temperature rise defined as:
the
⁢
core
⁢
entry
⁢
temperature
the
⁢
fan
⁢
rotor
⁢
entry
⁢
temperature
is in the range from 1.03 to 1.09.

### Claim 12 (depends on 11)

The gas turbine engine according to claim 11, wherein the fan root temperature rise is in the range from 1.05 to 1.07.

### Claim 13 (depends on 11)

The gas turbine engine according to claim 11, wherein a core compressor to fan root temperature rise ratio of
the
⁢
core
⁢
compressor
⁢
temperature
⁢
rise
the
⁢
fan
⁢
root
⁢
temperature
⁢
rise
is in the range from 2.76 to 4.10.

### Claim 14 (depends on 13)

The gas turbine engine according to claim 13, wherein the core compressor to fan root temperature rise ratio is in the range from 2.8 to 3.2.

### Claim 15 (depends on 1)

The gas turbine engine according to claim 1, wherein:
the turbine is a second turbine, the compressor is a second compressor, and the core shaft is a second core shaft;
the engine core further comprises a first turbine, a first compressor, and a first core shaft connecting the first turbine to the first compressor; and
the second turbine, second compressor, and second core shaft are arranged to rotate at a higher rotational speed than the first core shaft.

### Claim 16 (depends on 15)

The gas turbine engine according to claim 15, wherein a first turbine entrance temperature is defined as an average temperature of airflow at the entrance to the first turbine at cruise conditions and a first turbine exit temperature is defined as an average temperature of airflow at the exit from the first turbine at cruise conditions, and wherein a first turbine temperature change defined as:
the
⁢
first
⁢
turbine
⁢
entrance
⁢
temperature
the
⁢
first
⁢
turbine
⁢
exit
⁢
temperature
is in the range from 1.6 to 1.85.

### Claim 17 (depends on 16)

The gas turbine engine according to claim 16, wherein a turbine to fan tip temperature change ratio defined as:
the
⁢
first
⁢
turbine
⁢
temperature
⁢
change
the
⁢
fan
⁢
tip
⁢
temperature
⁢
rise
is in the range from 1.46 to 2.0.

### Claim 18 (depends on 1)

The gas turbine engine according to claim 1, wherein:
(i) the fan tip radius is in the range from 110 cm to 150 cm; or
(ii) the fan tip radius is in the range from 155 cm to 200 cm.

### Claim 19 (depends on 1)

The gas turbine engine according to claim 1, further comprising a gearbox that receives an input from the core shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the core shaft, and wherein the gearbox has a gear ratio in the range of from 3.2 to 5.

### Claim 20 (depends on 1)

A method of operating a gas turbine engine on an aircraft, wherein the method comprises:
operating the gas turbine engine to provide propulsion under cruise conditions according to claim 1.