A.À.Voskoboinick, A.V.Voskoboinick, V.A.Voskoboinick The characteristics of the pseudosound pressure fluctuations in a dimple at low Reynolds numbers |
Acoustic bulletin, Vol. 12 ¹ 4, (2009) |
| The paper deals with presenting of results of experimental studying of the velocity head and wall pressure fluctuations generated by vortical structures forming in a hemispherical cavity on the flat plate streamlined by the flow at low Reynolds numbers. The measurements were conducted by the group of miniature sensors of wall pressure fluctuations flush-mounted with the streamlined surface of the dimple and in its vicinity, as well as by sensors of velocity head fluctuations situated within the dimple above its surface. The root-mean-square values and power spectral densities of the investigated fields have been obtained. The effect of the hemispheric dimple on the integral and spectral characteristics of the pseudosound pressure fluctuations field has been shown. The specific features of generation of steady large-scale vortical structures and their interaction with the boundary layer above the plate have been pointed out. The tonal components conditioned by the rotation frequency of the symmetric large-scale vortical structure in the dimple (St≈0.1), its break-up frequency (St≈0.05) and frequency of self-induced vibrations of the vortical structures in shear layer (St≈0.4) have been found in spectra of the velocity head and wall pressure fluctuations. |
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KEY WORDS: streamlining of dimples, vortex structures, pressure fluctuations, pseudosound, power spectral density |
| TEXT LANGUAGE: Russian |