The asymmetry of the recirculation zone of the annular jet with different diameter ratio

We performed direct numerical simulations of the annular turbulent jet flow for the Reynolds number based on the bulk velocity inside the nozzle and its outer diameter Re = 8900 with three different values of the inner-to-outer diameter ratio a = d / D = 0.3, 0.5, 0.7. The size of the reversal flow region, the fluctuation level and mixing rate increase with the increase of the diameter ratio. For all the cases of geometry parameters the symmetry breaking phenomenon was detected. The degree of asymmetry increases with the increase of the diameter ratio resulting in the displacement of the global stagnation points form the axis of symmetry and the deflection of the averaged streamlines from the jet axis.