CFD-Led Designs of Pre-Filming Injectors for Gas-Turbine Combustors

The National Combustion Code (OpenNCC) was used to perform parametric design and analysis for three iterations of pre-filming injector design for gas-turbine combustors. The CFD analysis had significant impact on the design, integration and fabrication of a third-generation Lean-Direct Injection (LDI-3) flame-tube assembly consisting of nineteen injection elements. The air passages of the three pilot elements and sixteen main injection elements consisted of CFD-optimized compound-angle discrete jets and dual axial-bladed swirl-venturi passages, respectively. The aerodynamic characteristics of the nineteen-element injection array were evaluated by performing non-reacting flow simulation using a Time-Filtered Navier-Stokes (TFNS) method. The pilot and main injection elements were fueled with conventional pressure-atomizers and newly designed pre-filming nozzles, respectively. Fuel-air mixing and combustion performance was evaluated with reacting-flow TFNS computations using a 14-species, 18-step reduced kinetics mechanism for Jet-A fuel, Lagrangian spray modeling and a PDF turbulent-chemistry interaction model. The TFNS reacting-flow simulations provided considerable insight into the correlation between aerodynamics, combustion and emissions performance of the newly-designed pilot and main injection elements for the LDI-3 combustor at simulated cruise conditions.