Investigation of Flow Characteristics in Lean Direct Injection Combustors

This paper investigates nonreacting aerodynamic flow characteristics in lean direct injection (ID!) combustors. An unsteady Reynolds-averaged Navier-Stokes code of the Fluent (R) solver is used to simulate turbulent, nonreacting, and swirling flow associated with a single-element and a nine-element LDI combustor. Additionally, large eddy simulation is applied to simulate the flowfield within the nine-element combustor. Overall, for the single-element configuration, the numerical predictions both for time-averaged mean and turbulent flow velocity components compare well with the available measurement data. Between the two numerical methods being used for the nine-element configuration, the magnitude of velocities differ significantly near the combustion chamber inlet, although the velocity contour structures display similarities at all of the computed locations. The simulation captures aerodynamic flow features, such as the recirculation regions, the highly complex flow structures at the chamber entrance, and the interface of the adjacent swirlers. The highly turbulent flowfield and the presence of dynamic vortex structures in the proximity of the combustion chamber inlet indicate that a large degree of unsteadiness is associated with this region, which might favorably influence breakup and dispersion of liquid fuel droplets in a combustion simulation.