V.A.Voskoboinick Vortex formation inside cross-streamlined oval dimple |
Applied hydromechanics, Vol. 14 (86) ¹ 4, (2012) |
| In the paper the results of experimental researches of the vortex structure inside the cross-streamlined oval dimple on a hydraulically smooth flat surface are presented. By means of flow visualization by the contrasting dyes and water soluble coatings the features of forming and evolution of coherent large-scale and small-scale vortical structures are certain inside the dimple. For the Reynolds numbers, expected on the diameter of the dimple and flow velocity, less, than 4000, the large-scale vortices are not generated inside the oval dimple, and there is nonintensive low-frequency oscillation of liquid, filling the dimple. For the Reynolds numbers about 10000 the cellular quasistable large-scale vortical structures are formed inside the dimple, which are ejected above an aft dimple wall in its spherical parts and in a middle section. For the developed turbulent flow (Reynolds number more than 20000) a spindle form vortical structure is generated in the dimple which is pressed to the front bottom part of the dimple. Above an aft dimple wall there is the chaotic ejection of small-scale vortices, appearing at separation of top parts of the spindleform vortex (near-by a shear layer) as a vortex sheet |
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KEY WORDS: oval dimple, vortex, turbulent flow |
| TEXT LANGUAGE: Ukrainian |