Simulation of Turbulent Swirl Flow in an Axisymmetric Sudden Expansion

The numerical simulation of the turbulent flows in axisymmetric sudden expansions with inlet swirl is addressed, with the focus being on the unsteady flow behavior. Numerical simulations using the Reynolds-averaged Navier-Stokes equations closed via the k-e turbulence model are presented. Results for an expansion ratio of 1.96 and a Reynolds number of 1 x 10 5 (at the inlet) are presented for a range of swirl numbers from 0 to 0.48. The precessing vortex core (PVC) and most of the features observed experimentally, including the precession direction, zero-frequency swirl number, and vortex breakdown have been predicted