V.A.Voskoboinick Space-time correlations of the velocity and pressure fluctuations inside the hemispherical dimple |
Acoustic bulletin, Vol. 17 ¹ 3, (2015) |
| The specific features of mechanism of emergence and evolution of the coherent vortex structures forming inside the hemispherical cavity are experimentally studied along with the space-time characteristics of the velocity and pressure fluctuations fields generated inside the cavity and in its wake. The experiments are carried out in a hydrodynamic tray upon the hydraulically smooth plate with a hemispherical dimple. The fields of the velocity, dynamic and wall pressure fluctuations were recorded by a group of the hot-film thermoanemometers and miniature piezoelectric sensors of pressure fluctuations. The space-time correlations are obtained for the velocity and pressure fluctuations generated by the coherent large-scale vortex structures, circulation flow and vortex structure of the shear layer, which were formed inside the hemispherical dimple and ejected out into the boundary layer. The largest values of the space-time correlation coefficient for wall pressure fluctuations were observed on the aft and side walls of the hemispherical dimple, while the lowest ones occurred in its bottom part. The cross-correlations of the longitudinal velocity fluctuations were found to be higher than cross-correlations of the velocity and wall pressure fluctuations or those of the dynamic and wall pressure fluctuations. |
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KEY WORDS: space-time correlation, coherent vortex structure, hemispherical dimple, velocity and pressure fluctuations |
| TEXT LANGUAGE: Ukrainian |