Implicit les applied to isothermal swirling coaxial jets

This work is devoted to the analysis of the interaction of two coaxial jet with swirling flow using Large Eddy Simulation methodology to reproduce the case of Roback and Johnson. The eight - flat - vanes in the annular nozzle are the precursor of the swirling annular jet with high swirl number. An implicit LES model was used, this model uses mesh size as filter width so no sub-grid model is required. It is the numerical error who plays the role of dissipative part of the stress tensor in the sub-mesh. Mesh prerequisites are Ay+ = 1 and uniform hexahedral mesh. The resolution scheme used is a Total Variation Diminishing (TVD) with coefficients looking for good precision. PISO is the pressure-velocity coupling used. Besides, multigrid resolution improves the performance towards the full convergence. Influence of the swirl number on the flow pattern is analyzed. Also the impact of conical diffuser on the mixing is presented