V.A.Voskoboinick, A.V.Voskoboinick, A.A.Voskoboinick, V.N.Turik Velocity field in median section of the semispherical dimple |
Applied hydromechanics, Vol. 16 (88) ¹ 4, (2014) |
| The results of experimental researches of features of forming of vortical structures inside a hemispheric dimple on a hydraulically smooth flat surface and velocity field, which they generate, are presented in paper. Experiments were conducted in a wind tunnel and hydrodynamic channel by means of flow visualization and hot-wire and hot-film velocity measurements. Visualization by smoke, contrasting dyes and water-soluble coatings showed, that inside the dimple a quasistable large-scale vortical structure and small-scale vortices which are break-up outside from the dimple are generated. These vortical structures are originated from a circulation flow inside the dimple and shear layer which is boundary layer separation from a front wall of the dimple. A vortical flow inside the dimple is stimulated by appearance of discrete peaks in the frequency and wave velocity spectra on frequencies of low-frequency fluctuations of vertical flow, on frequencies of rotation and break-up of large-scale vortical structure and on frequencies of auto-oscillations of vortical structures of shear layer. |
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KEY WORDS: hemispheric dimple, vortical structure, velocity field, frequency and wave spectrum |
| TEXT LANGUAGE: Ukrainian |