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A pilot assembly for a fuel injector of a gas turbine engine may include a longitudinal passageway having an outlet end. A mass flow in the longitudinal passageway may generally flow towards the outlet end during operation of the engine. The pilot assembly may also include a liquid fuel nozzle that

A pilot assembly for a fuel injector of a gas turbine engine may include a longitudinal passageway having an outlet end. A mass flow in the longitudinal passageway may generally flow towards the outlet end during operation of the engine. The pilot assembly may also include a liquid fuel nozzle that is positioned to direct a mixture of liquid fuel and air near the outlet end, and a compressed air inlet that is configured to direct air compressed by a compressor of the engine to a compressor discharge pressure into the longitudinal passageway without a substantial loss of pressure. The longitudinal passageway may also include a flow restriction section. The flow restriction section may be a narrowed section of the longitudinal passageway, in which an upstream side of the flow restriction section may have compressed air at substantially the compressor discharge pressure and a downstream side may have air at a lower pressure and a higher velocity. The pilot assembly may further include a nozzle for injecting one of assist air or gaseous fuel into the longitudinal passageway. The nozzle may be positioned at the flow restriction section or on an upstream side of the flow restriction section to reduce cross-talk.

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1. A pilot assembly for a fuel injector of a gas turbine engine, comprising: a longitudinal passageway having an outlet end, a mass flow in the longitudinal passageway generally flowing towards the outlet end during operation of the engine;a liquid fuel nozzle positioned radially outwardly of the lo

1. A pilot assembly for a fuel injector of a gas turbine engine, comprising: a longitudinal passageway having an outlet end, a mass flow in the longitudinal passageway generally flowing towards the outlet end during operation of the engine;a liquid fuel nozzle positioned radially outwardly of the longitudinal passageway and configured to direct a mixture of liquid fuel and air around the outlet end of the longitudinal passageway;a compressed air inlet, the compressed air inlet being configured to direct air compressed by a compressor of the engine to a compressor discharge pressure into the longitudinal passageway without a substantial loss of pressure;a flow restriction section, the flow restriction section being a narrowed section of the longitudinal passageway, wherein an upstream side of the flow restriction section includes compressed air at substantially the compressor discharge pressure and a downstream side includes air at a lower pressure and a higher velocity;a gas fuel nozzle configured to inject a gaseous fuel into the longitudinal passageway at the flow restriction section; andan air assist nozzle configured to direct assist air into the longitudinal passageway upstream of the flow restriction section. 2. The pilot assembly of claim 1, wherein at least one of the gas fuel nozzle and the air assist nozzle is inactive during operation of the engine on liquid fuel. 3. The pilot assembly of claim 1, wherein the gas fuel nozzle is positioned at a distance of about 2 inches to about 6 inches from the outlet end. 4. The pilot assembly of claim 1, wherein the air assist nozzle is configured to direct assist air which is different from, and at a lower pressure than, the air compressed by the compressor of the engine into the longitudinal passageway. 5. The pilot assembly of claim 4, wherein the air assist nozzle is configured to direct assist air into the longitudinal passageway around the gas fuel nozzle. 6. The pilot assembly of claim 1, wherein at the flow restriction section, boundary walls of the longitudinal passageway converge inwardly to reduce a cross-sectional area available for fluid flow. 7. A method of reducing cross-talk through a fuel injector of a gas turbine engine, the cross-talk occurring as a result of combustion induced pressure variation in a combustor of the turbine engine, the fuel injector being configured to direct a stream of fuel-air mixture to the combustor through a pilot assembly and a separate stream of fuel-air mixture to the combustor through an annular duct disposed circumferentially about the pilot assembly, the pilot assembly including a centrally located longitudinal passageway having an outlet end fluidly coupled to the combustor, comprising: directing a liquid fuel into the combustor through the pilot assembly around the outlet end of the longitudinal passageway;delivering compressed air to the longitudinal passageway through a compressed air inlet upstream of a flow restriction section of the longitudinal passageway, the flow restriction section being a narrowed section of the longitudinal passageway that is configured to decrease a pressure and increase a velocity of the compressed air flowing therethrough;directing a gaseous fuel into the longitudinal passageway at the flow restriction section; anddirecting the compressed air delivered through the compressed air inlet to the combustor such that a pressure drop of the compressed air in the longitudinal passageway downstream of the flow restriction section is greater than or equal to an expected combustion induced pressure variation in the combustor. 8. The method of claim 7, wherein delivering compressed air to the longitudinal passageway includes delivering compressed air at a pressure substantially equal to a discharge pressure of a compressor of the gas turbine engine. 9. The method of claim 7, wherein the gas fuel nozzle is positioned at a distance of about 0.5 inches to about 10 inches from the outlet end. 10. The method of claim 7, wherein the gas fuel nozzle is positioned at a distance of about 2 inches to about 6 inches from the outlet end. 11. The method of claim 7, wherein the gas fuel nozzle is positioned in the longitudinal passageway such that the compressed air from the compressed air inlet flows substantially around the gas fuel nozzle. 12. The method of claim 7, further including deactivating the directing of the liquid fuel through the pilot assembly before directing the gaseous fuel into the longitudinal passageway. 13. The method of claim 7, further including directing assist air into the longitudinal passageway upstream of the compressed air inlet, the assist air being air that is different from, and at a lower pressure that, the compressed air directed into the longitudinal passageway through the compressed air inlet. 14. A fuel injector for a gas turbine engine, comprising: a tubular premix barrel disposed circumferentially about a longitudinal axis; anda pilot assembly positioned radially inwards of the premix barrel such that an annular duct is defined between the premix barrel and the pilot assembly, the pilot assembly including, a longitudinal passageway extending into the pilot assembly along the longitudinal axis, the longitudinal passageway including a compressed air inlet configured to discharge compressed air into the longitudinal passageway,a flow restriction section of the longitudinal passageway, the flow restriction section being positioned downstream of the compressed air inlet and being configured to decrease a pressure and increase a velocity of the compressed air flowing therethrough,a nozzle positioned in the longitudinal passageway proximate the flow restriction section, a location of the nozzle in the longitudinal passageway being such that a pressure drop of the compressed air in the longitudinal passageway downstream of the nozzle is greater than or equal to an expected combustion induced pressure variation in a combustor of the gas turbine engine, the nozzle being configured to inject one of gaseous fuel or assist air into the longitudinal passageway; anda liquid fuel nozzle positioned radially outwardly from the longitudinal passageway and downstream of the nozzle, the liquid fuel nozzle being configured to inject a liquid fuel into the pilot assembly. 15. The fuel injector of claim 14, wherein the compressed air inlet is configured to discharge compressed air at a pressure substantially equal to a discharge pressure of a compressor of the gas turbine engine into the longitudinal passageway. 16. The fuel injector of claim 14, wherein the nozzle is a gas fuel nozzle configured to inject the gaseous fuel into the longitudinal passageway and positioned at the flow restriction section of the longitudinal passageway. 17. The fuel injector of claim 16, wherein the fuel injector is configured to selectively deactivate one of the liquid fuel nozzle and the gas fuel nozzle while the gas turbine engine is operating. 18. The fuel injector of claim 16, wherein the gas fuel nozzle is positioned in the longitudinal passageway at a distance of about 2 inches to about 6 inches from an outlet of the longitudinal passageway into the combustor. 19. The fuel injector of claim 14, wherein the nozzle is an air assist nozzle configured to direct assist air into the longitudinal passageway and positioned upstream of the compressed air inlet, the assist air being different from, and at a lower pressure than, the compressed air directed into the longitudinal passageway through the compressed air inlet. 20. The fuel injector of claim 14, wherein at the flow restriction section, boundary walls of the longitudinal passageway converge inwardly to reduce a cross-sectional area available for fluid flow.