V.A.Voskoboinick, A.P.Makarenkov Spectral characteristics of the pseudo-sound components of hydrodynamical noise at a longitudinal flow of flexible cylinder |
Acoustic bulletin, Vol. 3 ¹ 2, (2000) |
| The wall pressure fluctuations were measured in an axisymmetric turbulent boundary layer on a flexible cylinder parallel to the mean flow at a Reynolds numbers of 107-108 and a boundary layer thickness to cylinder radius ratio of 2.9-3.2. It is revealed, that the intensity of pressure fluctuations of a turbulent boundary layer on the flexible cylinder is higher than that on a rigid cylinder and on a flat plate. The adjusted power spectrum of the pressure fluctuations is presented. The acoustic-hydrodynamic factor for the dot gauge of the pressure fluctuations is determined. It is established, that the power spectrum of the wall pressure fluctuations on the flexible cylinder is higher, than that on the rigid cylinder. With the increase of velocity of a flow of the flexible cylinder there occures a redistribution of energy of turbulent pressure fluctuations from the high frequency area of the power spectrum to low frequencies. In the frequency band w+~(0.2-0.3) the maximums of the power spectrum and the coherence function irrespective of separation between gauges of the pressure fluctuations are observed. With the increase of frequency and separation the coherence function descends, that characterizes a degeneracy of vortical structures as on scales, as on length of the streamlined cylinder. |
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KEY WORDS: towed long antennae, noise flow, turbulent pressure fluctuations, boundary layer |
| TEXT LANGUAGE: Russian |