Corner Vortex Structures: Large Eddy Simulations of a Confined, Premixed Bluff Body Stabilized Flame

The three-dimensional structure and dynamics of the recirculation zone downstream of confined, bluff-body-stabilized, turbulent, premixed flames are examined numerically. Non-reacting and reacting large eddy simulations are performed on a truncated, periodic domain and a full-span domain with spanwise walls using two mesh resolutions. The influence of spanwise walls on the size, shape, and intensity of the vortical structures in the recirculation zone are examined. The non-reacting results show that while the spanwise mean flow field is nominally uniform, turbulent statistics are sensitive to the choice of truncated or full-span domains with spanwise walls. The reacting results on the full-span domains show transverse-oriented vortices located in the corners between the bluff body trailing edge and spanwise walls. The corner vortex structures are larger than the boundary layers on the spanwise wall and can transport products into the main recirculation zone of the flow. The reacting flows show spanwise non-uniformity over the central portion of the domain typically considered to be spanwise uniform. It is recommended that future computational studies of confined bluff body stabilized flames with similar aspect ratios resolve the spanwise walls to properly model transport in the recirculation zone.