Influence of the Deep Spherical Dimple on the Pressure Field Under the Turbulent Boundary Layer
The influence of a local dimple in the form of a deep spherical cavity on the pressure field inside the dimple and its vicinity for the turbulent flow regime is experimentally determined. Specific features of the vortex formation inside the dimple are established and the influences of vortex structures that are ejected outward from the spherical dimple on the structure of the turbulent boundary layer are shown. The antiphase oscillations of the wall pressure fluctuation field occur in the halves of the dimple separated by a longitudinal axial plane when the vortex flow “switches” from one side of the dimple to another. The spectral components of the wall pressure fluctuations on the streamlined surface of the spherical dimple have discrete components corresponding to the frequencies of the “switching” of the vortex formation inside the dimple (St ≈ 0.003), the frequencies of the vortex ejections from the dimple (St ≈ 0.05) and the frequencies of the self-oscillations of the shear layer (St ≈ 0.4).
KeywordsSpherical dimple Vortex structure Wall pressure fluctuations
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