Fuel nozzle with restricted core air passage

An aircraft engine comprising:

• a combustor;
• and
• a plurality of fuel nozzles having nozzle tips projecting inside the combustor for injecting an air-fuel mixture into the combustor, at least one fuel nozzle of the plurality of fuel nozzles including:
• a nozzle body having a core air passage defined therein and extending centrally through the nozzle body in an axial direction from a core air inlet to a core air outlet at an outlet of the at least one fuel nozzle, and a fuel passage extending through the nozzle body between a fuel inlet and a fuel outlet located at the outlet end, the fuel passage being located radially outward of the core air passage;
• and
• at least two flow restrictors located within the core air passage, downstream of the core air inlet, the at least two flow restrictors disposed in series and including an upstream flow restrictor and a downstream flow restrictor, the upstream flow restrictor having an orifice therein defining an air flow passage and the downstream flow restrictor having one or more orifices therein respectively defining one or more air flow passages, the air flow passage of the upstream flow restrictor and the one or more air flow passages of the downstream flow restrictor having respective cross-sectional areas each of which is less than a cross-sectional area of the core air passage, the orifice in the upstream flow restrictor being at least partially offset from the one or more orifices in the downstream flow restrictor.

A method for delivering fuel into a combustor of an aircraft engine using a fuel nozzle, the method comprising:

• directing the fuel from a fuel source to a nozzle tip of the fuel nozzle;
• directing a core air flow through a core air passage extending centrally through the fuel nozzle;
• and
• within the core air passage, reducing an axial velocity of the core air flow by restricting the core air flow using at least two flow restrictors disposed in series within the core air passage, the at least two flow restrictors respectively including an upstream orifice and a downstream orifice, and decreasing a pressure drop across the downstream orifice when the core air flow passes through the downstream orifice.