Turbulence measurements in the bubbly flow region of hydraulic jumps |
| |
| Affiliation: | 1. Division of Civil Engineering, Zonguldak Karaelmas University, Zonguldak, Turkey;2. Division of Civil Engineering, The University of Queensland, Brisbane QLD 4072, Australia;1. Civil Engineering Department, Middle East Technical University, 06800 Ankara, Turkey;2. Civil Engineering Department, Çankaya University, Eskisehir Yolu 29.Km., 06790 Ankara, Turkey;1. Department of Water Engineering, Faculty of Agriculture, University of Birjand, Birjand, Iran;2. Department of Civil Engineering, Faculty of Engineering, University of Birjand, Birjand, Iran;3. Department of Water Structures Engineering, Faculty of Agriculture, University of Tabriz, Tabriz, Iran;1. Centre for Cardiovascular Sciences, Division of Clinical Sciences, St George''s University of London, London, UK;2. Queen Mary University of London, London, UK;3. CSL-Bioplasma Ltd, Melbourne, VIC, Australia;1. Viale dei Quattro Venti 233, 00152 Roma, Italie;2. 10, place Maréchal-Lannes, 32000 Auch, France;3. Department of civil, chemical and environmental studies, University of Genoa, Via Balbi 5, Genoa, Italie |
| |
| Abstract: | A hydraulic jump is characterized by a highly turbulent flow with macro-scale vortices, some kinetic energy dissipation and a bubbly two-phase flow structure. New air–water flow measurements were performed in a large-size facility using two types of phase-detection intrusive probes: i.e. single-tip and double-tip conductivity probes. These were complemented by some measurements of free-surface fluctuations using ultrasonic displacement meters. The void fraction measurements showed the presence of an advective diffusion shear layer in which the void fractions profiles matched closely an analytical solution of the advective diffusion equation for air bubbles. The free-surface fluctuations measurements showed large turbulent fluctuations that reflected the dynamic, unsteady structure of the hydraulic jumps. The measurements of interfacial velocity and turbulence level distributions provided new information on the turbulent velocity field in the highly-aerated shear region. The velocity profiles tended to follow a wall jet flow pattern. The air–water turbulent integral time and length scales were deduced from some auto- and cross-correlation analyses based upon the method of Chanson [H. Chanson, Bubbly flow structure in hydraulic jump, Eur. J. Mech. B/Fluids 26 (3) (2007) 367–384], providing the turbulent scales of the eddy structures advecting the air bubbles in the developing shear layer. The length scale Lxz is an integral air–water turbulence length scale which characterized the transverse size of the large vortical structures advecting the air bubbles. The experimental data showed that the dimensionless integral turbulent length scale Lxz/d1 was closely related to the inflow depth: i.e. Lxz/d1 = 0.2–0.8, with Lxz increasing towards the free-surface. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
