Gas turbine performance
A gas turbine engine for an aircraft is disclosed. The gas turbine engine comprises: a combustor, comprising a combustion chamber and a plurality of fuel spray nozzles configured to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor is operable in a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a greater fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles, wherein a ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6. A MTO nvPM emissions index ratio is defined as: EI maxTO , SAF EI maxTO , FF where: EI maxTO,SAF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 100% available thrust for given operating conditions if a fuel provided to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and EI maxTO,FF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 100% available thrust for the given operating conditions if a fuel provided to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel. The MTO nvPM emissions index ratio of the gas turbine engine is less than 1. The gas turbine engine is configured to provide fuel comprising a SAF to the plurality of fuel spray nozzles. Also disclosed are methods of operating the gas turbine engine.
1 . A gas turbine engine for an aircraft, comprising:
a combustor, comprising a combustion chamber and a plurality of fuel spray nozzles configured to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor is operable in a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a greater fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles, wherein a ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6;
a fuel distribution system; and
a controller configured to control the fuel distribution system to split fuel flow between the fuel spray nozzles of the combustor such that pilot injectors of the first subset of the fuel spray nozzles receive more fuel than pilot injectors of the second subset of the spray nozzles below a staging point, wherein the staging point is determined according to the composition of the fuel being provided to the plurality of fuel spray nozzles,
wherein:
a MTO nvPM emissions index ratio is defined as:
EI
maxTO
,
SAF
EI
maxTO
,
FF
where:
EI maxTO,SAF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 100% available thrust for given operating conditions if a fuel provided to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and
EI maxTO,FF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 100% available thrust for the given operating conditions if a fuel provided to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;
the MTO nvPM emissions index ratio of the gas turbine engine is less than 1; and
the gas turbine engine is configured to provide fuel comprising a SAF to the plurality of fuel spray nozzles.
2 . The gas turbine engine of claim 1 , wherein the MTO nvPM emissions index ratio is less than or equal to 0.93.
3 . The gas turbine engine of claim 1 , wherein the MTO nvPM emissions index ratio is greater than or equal to 0.15.
4 . The gas turbine engine of claim 1 , wherein:
a climb nvPM emissions index ratio is defined as:
EI
climb
,
S
A
F
EI
climb
,
FF
where:
EI climb,SAF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 85% available thrust for the given operating conditions, or for different given operating conditions, if a fuel provided to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and
EI climb,FF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 85% available thrust for the same given operating conditions at which EI climb,SA is calculated and if a fuel provided to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;
and the climb nvPM emissions index ratio of the gas turbine engine is less than 1.
5 . The gas turbine engine of claim 4 , wherein the climb nvPM emissions index ratio is less than or equal to 0.9.
6 . The gas turbine engine of claim 4 , wherein the climb nvPM emissions index ratio is greater than or equal to 0.1.
7 . The gas turbine engine of claim 1 , wherein:
an approach nvPM emissions index ratio is defined as:
EI
a
p
p
r
o
a
c
h
,
S
A
F
EI
a
p
p
r
o
a
c
h
,
F
F
where:
EI approach,SAF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 30% available thrust for the given operating conditions, or for different given operating conditions, if a fuel provided to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and
EI approach,FF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 30% available thrust for the same given operating conditions at which EI approach,SAF is calculated and if a fuel provided to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and
the approach nvPM emissions index ratio of the gas turbine engine is less than 1.
8 . The gas turbine engine of claim 7 , wherein the approach nvPM emissions index ratio is less than or equal to 0.8.
9 . The gas turbine engine of claim 7 , wherein the approach nvPM emissions index ratio is greater than or equal to 0.03.
10 . The gas turbine engine of claim 1 , wherein:
an idle nvPM emissions index ratio is defined as:
EI
idle
,
SAF
EI
idle
,
FF
where:
EI idle,SAF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 7% available thrust for the given operating conditions, or for different given operating conditions, and if a fuel provided to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and
EI idle,FF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 7% available thrust for the same given operating conditions at which EI idle,SAF is calculated and if a fuel provided to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and
the idle nvPM emissions index ratio of the gas turbine engine is less than 1.
11 . The gas turbine engine of claim 10 , wherein the idle nvPM emissions index ratio is less than or equal to 0.8.
12 . The gas turbine engine of claim 10 , wherein the idle nvPM emissions index ratio is greater than or equal to 0.02.
13 . The gas turbine engine of claim 1 , wherein the ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:4 to 1:5; and/or wherein the first subset of fuel spray nozzles includes between 1 and 10 fuel spray nozzles; and wherein the second subset of fuel spray nozzles includes between 10 and 25 fuel spray nozzles.
14 . The gas turbine engine of claim 1 , wherein the combustor comprises one or more ignitors, wherein each of the first subset of fuel spray nozzles is located nearer a respective one or more of the ignitors than the second subset, and/or wherein one or more of the ignitors is arranged diametrically opposite another one or more of the ignitors.
15 . The gas turbine engine of claim 1 , wherein the fuel provided to the plurality of fuel spray nozzles comprises a % SAF in the range of 50% to 100%.
16 . A method of operating the gas turbine engine of claim 1 , the method comprising providing fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles.
17 . The gas turbine engine of claim 1 , wherein
above the staging point, all of the pilot injectors receive the same amount of fuel.
18 . A method of operating a gas turbine engine, the gas turbine engine comprising:
a combustor, comprising a combustion chamber and a plurality of fuel spray nozzles configured to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor is operable in a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a greater fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles, wherein a ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6;
a fuel distribution system; and
a controller configured to control the fuel distribution system,
wherein:
a MTO nvPM emissions index ratio is defined as:
EI
maxTO
,
SAF
EI
maxTO
,
FF
where:
EI maxTO,SAF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 100% available thrust for given operating conditions if a fuel provided to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and
EI maxTO,FF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 100% available thrust for the given operating conditions if a fuel provided to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and
the MTO nvPM emissions index ratio of the gas turbine engine is less than 1; and
the method comprises
providing fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles; and
controlling the fuel distribution system to split fuel flow between the fuel spray nozzles of the combustor such that pilot injectors of the first subset of the fuel spray nozzles receive more fuel than pilot injectors of the second subset of the spray nozzles below a staging point, wherein the staging point is determined according to the composition of the fuel being provided to the plurality of fuel spray nozzles.
19 . The method of claim 18 , wherein:
a climb nvPM emissions index ratio is defined as:
EI
climb
,
S
A
F
EI
climb
,
FF
where:
EI climb,SAF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 85% available thrust for the given operating conditions, or for different given operating conditions, if a fuel provided to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and
EI climb,FF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 85% available thrust for the same given operating conditions at which EI climb,SAF is calculated and if a fuel provided to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and
the climb nvPM emissions index ratio of the gas turbine engine is less than 1.
20 . The method of claim 18 , wherein:
an approach nvPM emissions index ratio is defined as:
EI
a
p
p
r
o
a
c
h
,
S
A
F
EI
a
p
p
r
o
a
c
h
,
F
F
where:
EI approach,SAF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 30% available thrust for the given operating conditions, or for different given operating conditions, if a fuel provided to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and
EI approach,FF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 30% available thrust for the same given operating conditions at which EI approach,SAF is calculated and if a fuel provided to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and
the approach nvPM emissions index ratio of the gas turbine engine is less than 1.
21 . The method of claim 18 , wherein:
an idle nvPM emissions index ratio is defined as:
EI
idle
,
SAF
EI
idle
,
FF
where:
EI idle,SAF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 7% available thrust for the given operating conditions, or for different given operating conditions, and if a fuel provided to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and
EI idle,FF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 7% available thrust for the same given operating conditions at which EI idle,SAF is calculated and if a fuel provided to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel; and
the idle nvPM emissions index ratio of the gas turbine engine is less than 1.
22 . The method of claim 18 , wherein
above the staging point, all of the pilot injectors receive the same amount of fuel.
23 . A gas turbine engine for an aircraft, comprising:
a combustor, comprising a combustion chamber and a plurality of fuel spray nozzles configured to inject fuel into the combustion chamber, wherein the plurality of fuel spray nozzles comprises a first subset of fuel spray nozzles and a second subset of fuel spray nozzles, wherein the combustor is operable in a condition in which each of the fuel spray nozzles of the first subset of fuel spray nozzles is supplied with fuel at a greater fuel flow rate than each of the fuel spray nozzles of the second subset of fuel spray nozzles, wherein a ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:3 to 1:6;
a fuel distribution system including at least one fuel-oil heat exchanger; and
a controller configured to control the at least one fuel-oil heat exchanger to control at least one of a temperature of the fuel on entry to the combustor and a viscosity of the fuel on entry to the combustor according to the composition of fuel being provided to the plurality of fuel spray nozzles,
wherein:
a MTO nvPM emissions index ratio is defined as:
EI
maxTO
,
SAF
EI
maxTO
,
FF
where:
EI maxTO,SAF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 100% available thrust for given operating conditions if a fuel provided to the plurality of fuel spray nozzles comprises a sustainable aviation fuel (SAF); and
EI maxTO,FF is the nvPM emissions index in mg/kg of the gas turbine engine when operating at around 100% available thrust for the given operating conditions if a fuel provided to the plurality of fuel spray nozzles is a fossil-based hydrocarbon fuel;
the MTO nvPM emissions index ratio of the gas turbine engine is less than 1; and
the gas turbine engine is configured to provide fuel comprising a SAF to the plurality of fuel spray nozzles.