DUAL-SPRAY AIRBLAST FUEL NOZZLE FOR ADVANCED SMALL GAS-TURBINE COMBUSTORS

A novel dual-spray airblast fuel nozzle that has the potential of impr oved light-off capability and higher combustor turndown fuel-air ratio is being developed for advanced military small gas-turbine engines. F eatures of the nozzle include: 1) full integration of the combustor do me swirler and two airblast atomizers (pilot and main) into a single f unctional unit, 2) minimum fuel flow passages greater than 0.018 in., and 3) integration and optimization of the primary zone airflow and sp ray patterns to substantially increase combustor turndown fuel-air rat ios. Nine research versions of the nozzle were designed, fabricated, a nd tested. Measurements of effective flow area (ACd), spray angle, ato mization quality, and air velocity were used to screen the designs. Th e best nozzle configurations were tested for ignition and lean blowout in a single-nozzle combustor front-end at ambient conditions. To asce rtain the effect of nozzle-nozzle interaction, the best configuration was tested in a three-nozzle combustor front-end. Identical ignition a nd lean-blowout results were obtained as compared to single-nozzle tes ts. The best nozzle design could be lit at a pressure drop of 1.25 in. of water and a fuel flow of 1.5 pph per nozzle.