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US-12618370-B2 - Emissions of non-volatile particulate matter from gas turbine engines combusting sustainable aviation fuel and fossil-based hydrocarbon fuel

US12618370B2US 12618370 B2US12618370 B2US 12618370B2US-12618370-B2

Abstract

A gas turbine engine for an aircraft. The gas turbine engine comprising: a rich burn, quick quench, lean burn (RQL) combustor having a number of fuel spray nozzles in the range of 14-22 or a number of fuel spray nozzles per unit engine core size in the range 2 to 6. An MTO nvPM emissions index ratio is defined as: EI maxTO , SAF EI maxTO , FF where: EI maxTO,SAF is the system loss corrected 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 fuel spray nozzles comprises a sustainable aviation fuel (SAF); and EI maxTO,FF is the system loss corrected 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 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 fuel spray nozzles. Also disclosed is a method of operating a gas turbine engine.

Inventors

  • Christopher P Madden
  • Peter SWANN

Assignees

  • ROLLS-ROYCE PLC

Dates

Publication Date
20260505
Application Date
20250605
Priority Date
20240610

Claims (20)

  1. 1 . A gas turbine engine for an aircraft, comprising: a rich burn, quick quench, lean burn (RQL) combustor having a number of fuel spray nozzles in the range of 14-22 or a number of fuel spray nozzles per unit engine core size in the range 2 to 6 where engine core size is defined, at a top of climb operating condition, as: Core ⁢ size = m . 2 ⁢ T 3 P 3 , where {dot over (m)} 2 =mass flow rate, in lbs per second, of air on entry to a high-pressure compressor, T 3 =temperature, in Kelvin, of air on exit from the high-pressure compressor, and P 3 =pressure, in lb inches per second squared per inch squared, of air on exit from the high-pressure compressor such that a unit of core size is expressed as: s · K 1 2 · in ; and wherein: an MTO nvPM emissions index ratio is defined as: EI maxTO , SAF EI maxTO , FF where: EI maxTO,SAF is the system loss corrected 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 fuel spray nozzles comprises a sustainable aviation fuel (SAF); and EI maxTO,FF is the system loss corrected 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 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 fuel spray nozzles, wherein the fuel spray nozzles comprises one or more duplex nozzles and one or more single flow nozzles; and the combustor comprises one or more ignitors each arranged adjacent to one or more of the duplex nozzles, and/or wherein the number of fuel spray nozzles per unit engine core size is in the range 2.5 to 4.5.
  2. 2 . The gas turbine engine of claim 1 , wherein the MTO nvPM emissions index ratio is less than or equal to 0.93.
  3. 3 . The gas turbine engine of claim 1 , wherein the MTO nvPM emissions index ratio is greater than or equal to 0.15.
  4. 4 . The gas turbine engine of claim 1 , wherein a climb nvPM emissions index ratio is defined as: EI climb , SAF EI climb , FF where: EI climb,SAF is the system loss corrected 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 fuel spray nozzles comprises a sustainable aviation fuel (SAF); and EI climb,FF is the system loss corrected 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 fuel spray nozzles is a fossil-based hydrocarbon fuel; and wherein the climb nvPM emissions index ratio of the gas turbine engine is less than 1.
  5. 5 . The gas turbine engine of claim 4 , wherein the climb nvPM emissions index ratio is less than or equal to 0.9.
  6. 6 . The gas turbine engine of claim 4 , wherein the climb nvPM emissions index ratio is greater than or equal to 0.1.
  7. 7 . The gas turbine engine of claim 1 , wherein an approach nvPM emissions index ratio is defined as: EI approach , SAF EI approach , FF where: EI approach,SAF is the system loss corrected 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 fuel spray nozzles comprises a sustainable aviation fuel (SAF); and EI approach,FF is the system loss corrected 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 fuel spray nozzles is a fossil-based hydrocarbon fuel; and wherein the approach nvPM emissions index ratio of the gas turbine engine is less than 1.
  8. 8 . The gas turbine engine of claim 7 , wherein the approach nvPM emissions index ratio is less than or equal to 0.8.
  9. 9 . The gas turbine engine of claim 7 , wherein the approach nvPM emissions index ratio is greater than or equal to 0.03.
  10. 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 system loss corrected 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 fuel spray nozzles comprises a sustainable aviation fuel (SAF); and EI idle,FF is the system loss corrected 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 fuel spray nozzles is a fossil-based hydrocarbon fuel; and wherein the idle nvPM emissions index ratio of the gas turbine engine is less than 1.
  11. 11 . The gas turbine engine of claim 10 , wherein the idle nvPM emissions index ratio is less than or equal to 0.8.
  12. 12 . The gas turbine engine of claim 10 , wherein the idle nvPM emissions index ratio is greater than or equal to 0.02.
  13. 13 . The gas turbine engine of claim 1 , wherein the fuel provided to the fuel spray nozzles comprises a % SAF in the range of 50% to 100%.
  14. 14 . A method of operating the gas turbine engine of claim 1 , the method comprising providing fuel comprising a sustainable aviation fuel to the fuel spray nozzles.
  15. 15 . The gas turbine engine of claim 1 , wherein the top of climb occurs at 30,000 to 39,000 feet, a forward speed of Mach Number 0.75 to 0.85, and ambient air temperature of ISA+10K to ISA+15K.
  16. 16 . The gas turbine engine of claim 15 , wherein the top of climb occurs at 35,000 feet.
  17. 17 . A method of operating a gas turbine engine, the gas turbine engine comprising: a rich burn, quick quench, lean burn (RQL) combustor having a number of fuel spray nozzles in the range of 14-22 or a number of fuel spray nozzles per unit engine core size in the range 2 to 6 where engine core size is defined, at a top of climb operating condition, as: Core ⁢ size = m . 2 ⁢ T 3 P 3 , where {dot over (m)} 2 =mass flow rate, in lbs per second, of air on entry to a high-pressure compressor, T 3 =temperature, in Kelvin, of air on exit from the high-pressure compressor, and P 3 =pressure, in lb inches per second squared per inch squared, of air on exit from the high-pressure compressor such that a unit of core size is expressed as: s · K 1 2 · in ; and wherein an MTO nvPM emissions index ratio is defined as: EI maxTO , SAF EI maxTO , FF where: EI maxTO,SAF is the system loss corrected 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 fuel spray nozzles comprises a sustainable aviation fuel (SAF); and EI maxTO,FF is the system loss corrected 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 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 fuel spray nozzles; the fuel spray nozzles comprises one or more duplex nozzles and one or more single flow nozzles; and the combustor comprises one or more ignitors each arranged adjacent to one or more of the duplex nozzles, and/or wherein the number of fuel spray nozzles per unit engine core size is in the range 2.5 to 4.5; wherein the method comprises providing fuel comprising a sustainable aviation fuel to the fuel spray nozzles.
  18. 18 . The method of claim 17 , wherein a climb nvPM emissions index ratio is defined as: EI climb , SAF EI climb , FF where: EI climb,SAF is the system loss corrected 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 fuel spray nozzles comprises a sustainable aviation fuel (SAF); and EI climb,FF is the system loss corrected 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 fuel spray nozzles is a fossil-based hydrocarbon fuel; and wherein the climb nvPM emissions index ratio of the gas turbine engine is less than 1.
  19. 19 . The method of claim 17 , wherein an approach nvPM emissions index ratio is defined as: EI approach , SAF EI approach , FF where: EI approach,SAF is the system loss corrected 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 fuel spray nozzles comprises a sustainable aviation fuel (SAF); and EI approach,FF is the system loss corrected 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 fuel spray nozzles is a fossil-based hydrocarbon fuel; and wherein the approach nvPM emissions index ratio of the gas turbine engine is less than 1.
  20. 20 . The method of claim 17 , wherein an idle nvPM emissions index ratio is defined as: EI idle , SAF EI idle , FF where: EI idle,SAF is the system loss corrected 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 fuel spray nozzles comprises a sustainable aviation fuel (SAF); and EI idle,FF is the system loss corrected 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 fuel spray nozzles is a fossil-based hydrocarbon fuel; and wherein the idle nvPM emissions index ratio of the gas turbine engine is less than 1.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. application Ser. No. 18/892,666 filed on 23 Sep. 2024, which claims priority from United Kingdom Patent Application Number 2408243.0 filed on 10 Jun. 2024. The entire contents of each of these applications are incorporated herein by reference in their entirety. BACKGROUND Field of the Disclosure The present disclosure relates to the emissions of non-volatile particulate matter (nvPM) from gas turbine engines, specifically gas turbine engines for an aircraft. The present disclosure provides various methods of operating a gas turbine engine and gas turbine engines. Aspects of the present application relate to methods of operating gas turbine engines using a fuel which comprises a sustainable aviation fuel (SAF) and gas turbine engines configured to operate using fuel comprising a SAF. Description of the Related Art There is an expectation in the aviation industry of a trend towards the use of fuels different from the traditional kerosene-based jet fuels generally used at present. The inventors have identified that the emissions of a gas turbine engine are sensitive to the fuel being used, in particular the amount of nvPM produced by the engine varies depending on the operating parameters and the type of fuel being used. Thus, there is a need to take account of fuel properties of these different fuels and to adjust methods of operating gas turbine engines accordingly. SUMMARY According to a first aspect, there is provided a gas turbine engine for an aircraft, comprising any one or more of the following features: a rich burn, quick quench, lean burn (RQL) combustor having a number of fuel spray nozzles in the range of 14-22 or a number of fuel spray nozzles per unit engine core size in the range 2 to 6; andwherein:a first idle-MTO nvPM emissions index ratio may be defined as: EIidleEImaxTOwhere:EIidle is the system loss corrected nvPM emissions index in mg/kg of the gas turbine engine if operating at around 7% available thrust for given operating conditions; andEImaxTO is the system loss corrected nvPM emissions index in mg/kg of the gas turbine engine if operating at around 100% available thrust for the given operating conditions;the first idle-MTO nvPM emissions index ratio of the gas turbine engine is less than 0.8; andthe gas turbine engine is configured to provide fuel comprising a sustainable aviation fuel (SAF) to the fuel spray nozzles. Advantageously, reduced nvPM in the exhaust of a gas turbine engine contributes to a reduction in undesirable emissions of the engine. For example, according to operational conditions, reducing nvPM in such a manner may lead to a reduced degree of soot deposits within the engine within and/or downstream of the combustor, and/or an improvement in local air quality. Furthermore, at certain stages of an aircraft flight (where contrails are otherwise expected to form) reduced nvPM in the exhaust may lead to reduced contrail strength and/or time taken for a contrail to disperse. Still further, it has been recognised that certain parts of the flight cycle at which the nvPM is reduced (or most reduced) can be targeted in order to achieve a desired outcome, for example in terms of environmental impact. Purely by way of example, lower nvPM at cruise conditions may particularly reduce the radiative forcing impact of contrails. Purely by way of further example, lower nvPM at idle conditions may particularly improve local air quality on the ground in the region of engine operation. Purely by way of further example, lower nvPM at MTO conditions may particularly reduce the maximum rate of nvPM production during the flight cycle and/or improve air quality on the ground and/or in the region of engine operation. These considerations may apply to all aspects of the disclosure. A number of parameters related to gas turbine engine operation have been determined to have an influence on, or are an important factor in, the configuration and arrangement of the combustor of the engine when certain types of fuel, such as a sustainable aviation fuel, are being combusted. Accordingly, any one or more parameters of the following aspects may be advantageously taken into account when determining, for example, operational settings, combustor arrangement and/or combustor configuration, to influence and/or optimise how that fuel is to be distributed, ignited, and/or combusted within the gas turbine engine. These considerations may apply to all aspects of the disclosure. The first idle-MTO nvPM emissions index ratio of the gas turbine engine may be greater than zero. The first idle-MTO nvPM emissions index ratio may be less than 0.708 and preferably less than 0.649 and more preferably less than 0.59. The first idle-MTO nvPM emissions index ratio may be less than or equal to 0.5 and preferably less than or equal to 0.4 and more preferably less than or equal to 0.3. The first idle-MTO nvPM emissions index ratio may be less th