Author(s): David Stefan; Ondrej Urban; Pavel Rudolf

Linked Author(s):

Keywords: Swirl ratio; Columnar vortices; Swirl generator; Mixing mechanism; CFD simulation

Abstract: The study presents analysis of conditions for the onset of columnar vortices in the mixing part of swirl generator. The simplified geometry, used for this analysis, is based on the physical model of the bladeless swirl generator developed by the research group from Brno University of Technology. This swirl generator was previously used for several studies of the spiral vortex structures generated in the diffuser part. The main aim for the current study is the mixing mechanism, which is realized in the part where the axial inflow meets the tangential one. Since there are no guide vanes or other driving geometry features, the mixing mechanism is realized randomly, is strongly time-dependent and its behavior is linked to the swirl ratio between the axial and tangential inflows. From previous studies, the appearance of vortical structures with columnar-like shape was identified. For the better understanding of this mixing mechanism, which may influence the flow downstream and consequently the generated vortex, the several swirl ratios of axial and tangential inflow were studied. The dynamic of vortices are extracted using A-f analysis and proper orthogonal decomposition. The results are based on the CFD simulation employing a hybrid RANS+LES turbulence models.

DOI: https://doi.org/10.1088/1755-1315/1483/1/012032

Year: 2023