Large eddy simulation of spray dispersion and mixing in a swirl stabilized gas turbine burner

The dispersion of droplets and mixing of evaporated gases in a swirl stabilized gas turbine combustor are studied with an Eulerian / Lagrangian approach. The results are shown to be highly sensitive to the assumed droplet injection diameter. Injection of smaller droplet diameters lead to significantly higher local equivalence ratios and temperature drops, and increased gas phase densities, enhancing further the breakup of the droplets non-linearly. A spiraling rotational mode in the combustor, the precessing vortex core, leads to time-dependent local mixture fractions with bi-modal probability density functions. Small droplets and evaporated gases can enter the swirl generator intermittently with a frequency related to this rotational mode