Anti-coke fuel nozzle

A dual orifice type fuel nozzle for a combustor of gas turbine engine having a compressor, said fuel nozzle having a generally conically shaped casing with a primary fuel passage centrally disposed therein, secondary fuel passage formed therein concentrically disposed relative to the primary fuel passage, both primary and secondary passages exiting fuel into said combustor through a substantially mutual transverse plane, means for imparting a swirl component to compressor discharge air surrounding the fuel exiting from said primary and secondary passages, means for feeding fuel to said primary fuel passage so that it is normally continuously operative throughout the engine operating envelope and means for feeding fuel to said secondary fuel passage so that it is normally operative solely during the high thrust regimes and inoperative during the low thrust regimes of said engine operating envelope, means for pressurizing the secondary passage when said primary passage is solely operative with said compressor discharge air whereby said secondary passage maintains a positive pressure for preventing fuel from said primary passage from migrating therein and coking the walls of said secondary passage.