A New Hybrid Air Blast Nozzle for Advanced Gas Turbine Combustors

The push towards higher specific fuel consumption and smaller, lighter packaging for aerospace gas turbine engines has resulted in large increases in engine operating pressure and temperature. This is a trend that is expected to continue, and as a result, thermal management of the hot engine section including the fuel nozzle, combustor, and turbine has emerged as a critical technology area requiring further development. For the fuel injection system, nozzle thermal management, turndown ratio, and atomization performance while maintaining correct combustor aerodynamics are the most important performance features that necessitate optimization. Significant advances in fuel injection concepts are required to meet the increasingly demanding combustor requirements. Complex heat-shielded designs are often required to reduce nozzle wetted-wall temperatures and prevent the formation of carbonaceous deposits within the fuel delivery passages. To support the development of advanced combustors and address these increasing performance demands, Parker has developed a new Hybrid Air Blast nozzle. Advanced analytical and experimental design tools were applied to reduce the cut-and-try approach previously used in nozzle development. The developed hybrid air blast design achieved excellent atomization performance over a wide range of fuel flow rates and air pressure drops. Thermal analysis of the nozzle showed that the wetted wall temperatures were reduced considerably when compared to previous designs operating at the same conditions. Eight-port circumferential spray patternation results were outstanding with the patternation factor at various values of liquid flow rate ranging between 0.12 and 0.18. This patternation factor is a significant improvement over those of current state-of-the-art injectors that are typically of the order of 0.25.