V.A.Voskoboinick, A.V.Voskoboinick, A.A.Voskoboinick Vortex generation by a couple of oval cavities on flowing plane surface |
Applied hydromechanics, Vol. 17 (89) ¹ 3, (2015) |
| In study visual researches of characteristic features of a flow around of pair of the oval dimples on hydraulically smooth flat plate are conducted. It is established that depending on the flow regime inside the oval dimples are formed potential and vortex currents with ejection of vortex structures outside of dimples in the boundary layer. In the conditions of a laminar flow a vortex motion inside dimples is not observed, and not intensive oscillation of the liquid filling holes takes place. With increase of flow velocity in dimples there is a boundary layer separation, and inside the oval dimples the shear layer, potential and circulating flows are formed. The potential flow takes place near forward dimple walls, and the circulating flow generates a large-scale spiral vortex which has a source on forward spherical parts of the dimples. In the conditions of the turbulent regime of a flow the potential motion disappears, and intensive vortex motion is formed. In forward spherical parts of dimples large-scale fusiform vortices are generated which are ejected outside of the dimples in a boundary layer. Ejection of large-scale vortex systems happens to frequencies which are answered Strouhal number 0.05. Interaction of vortex structures which are ejected of each dimple, in median section between the oval dimples and in their near wake it isn’t observed. |
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KEY WORDS: pair of oval dimples, potential and circulating flow, vortex structure, spiral vortex, fusiform vortex, large-scale vortex ejection |
| TEXT LANGUAGE: Ukrainian |