Prefilming air blast (PAB) pilot for low emissions combustors

A pilot fuel injector of a fuel nozzle of a gas turbine engine, comprising:

• an axially-elongated, inner pilot centerbody wall extending from an upstream end to a downstream end, wherein the axially-elongated, inner pilot centerbody wall has a diverging-converging orientation with respect to a centerline axis to define a hollow tube having an upstream diameter, a throat, and a downstream diameter, wherein the throat has an inner diameter that is less than both of the upstream diameter and the downstream diameter, and wherein the inner diameter of the throat occurs at a single axial location relative to the centerline axis;
• a center air circuit positioned at the upstream end of the hollow tube, wherein the center air circuit is defined by a center swirler having center swirl vanes;
• an annular fuel passage defining the downstream end of the pilot fuel injector, the annular fuel passage intersecting with the axially-elongated, inner pilot centerbody wall at a pilot fuel metering orifice;
• a pilot fuel film surface downstream from the annular fuel passage;
• an outer pilot centerbody wall surrounding the axially-elongated, inner pilot centerbody wall;
• a pilot fuel cartridge positioned between the axially-elongated, inner pilot centerbody wall and the outer pilot centerbody wall, wherein the pilot fuel cartridge is in fluid communication with the annular fuel passage so as to provide fuel therethrough and onto the pilot fuel film surface;
• and
• an inner purge air inlet port extending from an inner purge air cavity defined between the axially-elongated, inner pilot centerbody wall and the pilot fuel cartridge,
• wherein the throat is positioned between the center swirler and the pilot fuel metering orifice, and
• wherein inner purge air in the inner purge air cavity is configured to flow from the inner purge air cavity into the hollow tube through the inner purge air inlet port placed in series with a controlled exit gap dimension.