This present work investigates the external aerodynamics of a lean-burn gas turbine fuel-flexible injector using particle image velocimetry (PIV) experiments. The complex aerodynamics of the injector is studied to obtain the velocity flow fields generated by the main and pilot swirler sections of the injector and to capture the central toroidal recirculation zone (CTRZ) at the injector exit. The fuel flex injector assembly consists of a pilot and main mixer. The pilot mixer consists of primary and secondary swirlers arranged co-axially in clockwise and counter-clockwise directions. The main mixer consists of three swirlers in which the primary swirler of the main mixer is arranged co-axially with pilot mixer while the secondary and tertiary swirlers of the main mixer are arranged radially. The efficient CTRZ is achieved through optimized swirlers in the geometry. The velocity flow field is visualized on different flow rates using low-speed PIV for the pilot, main, and full injectors separately. A symmetric and small CTRZ is observed at the exit of the pilot mixer. Similarly, a symmetric and larger CTRZ is observed at the exit of main mixer. A combined and bigger CTRZ with a strong shear layer is observed at the exit of the full injector.