Large-eddy simulations of the near field of a swirling turbulent annular jet

We perform Large-eddy simulations of an annular swirling turbulent jet for S = 0, S = 0.3 and S = 1, where S is swirl number. The Reynolds number based on the bulk velocity in the feeding channel and the outer diameter was 8900. The analysis showed that the region around the stagnation point in the end of the recirculation zone has a high level of turbulent kinetic energy. The length of the recirculation zone decreases in case for low swirl (S = 0.3) compared to the non-rotating case, while for the higher rotation rate (S = 1) the recirculation bubble becomes enormously long. Spectral analysis showed two peaks corresponding to the Kelvin-Helmholtz instability and some low-frequency oscillations of the recirculating zone.