A.V.Voskoboinick, V.A.Voskoboinick, À.A.Voskoboinick Junction flows of the three-row pile grillage on a flat plate. Part 2. Space-time correlations and spectra |
Applied hydromechanics, Vol. 10 (82) ¹ 4, (2008) |
| The experimental research results on the study of kinematics and dynamics of the horseshoe vortex systems, which are conditioned by interaction of stream with the three-row pile grillage, established on a flat rigid surface, are represented in this work. For carrying out of experiments the measuring complex, system of processing and the analysis of the data is developed and created. The miniature thermistor velocity sensors and piezoresistive velocity head sensors are made. The convective velocity measurements of vortical structures near to bridge pair models was made by the thermistor sensors which are taking place in the correlation block that has allowed to determine not only velocity, but also a movement direction of the large-scale coherent vortices in the junction flows. Short-time (instantaneous) spectral and cross-correlation characteristics are shown on spectorgrams and correlograms. This is allowed to investigate the non-stationary and discontinuity velocity fluctuations in a vortical stream. The large-scale horseshoe vortex by a diameter 0.3d is formed before front central pile and his center is disposed in the distance (0.15-0.19)d from the surface of circular cylinder and (0.11-0.15)d from the plate surface. The horseshoe vortex system before the central pile is turned with frequency near 1 Hz, which is corresponded by the Strouhal number St=0.27, and its oscillated in a horizontal and vertical plane with frequency 0.5 Hz or St=0.14. |
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| TEXT LANGUAGE: Ukrainian |