Turbulent Vortex Scales In Open-channel Of Large Depth

It is significant for recognizing fine sediment siltation and improving the forcastaccuracy of The Three Gorges’ sediment siltation to study The Three Gorges reservoirregular backwater area turbulent fluctuation with large water depth. Builded anadvanced large water depth turbulent fluctuation prototype measurement system,which is used to observe the three dimensional fluctuation velocity of Huang HuaCheng in Zhong Xian and the river estuary of Mei Xi River reach in Feng Jie whosesediment siltation is the most serious in The Three Gorges Reservoir regular backwaterarea.41vertical lines and320measurement points are arranged. Through measurementdata and theory analysis, three dimensional time average velocity and turbulencevortex scales are discussed in detail.1. In this paper, fluctuation turbulence amplitude of deep water open channelreflected in the water depth non-uniform number.2. The vortex structure of different scales are common in throughout the depth ofturbulent water，energy of the large scale vortex average accounts for turbulent kineticenergy84.14%，Even can reach above95%，Larger than the uniform flow(50-70%).3. Within a whole large scale vortex structure, four quadrant pulses (Q1, Q2, Q3,and Q4) are present. Instantaneous distribution of Reynolds stress is not only related toQ2and Q4, but also related to the Q1and Q3.4. Turbulent flow could be divided into three kinds of vortex scales. Turbulentflow in open channel is thought to consist of grade Ⅰ level vortex structure.Itswavelength is0.4to0.5times of the water depth. Superposition relationship existsamong the four kinds of vortex scales. Ⅱ level vortex and Ⅲ level vortex scale is asthe1/15-1/10of the higher level of vortex，zones of uniform momentum is1/3of theⅢ vortex scale，the scale of level of the vortex inertial sub-area and dissipation-areaare closed to the critical dimensions. Energetic vortex area and most of the inertia areascale are contained in zones of uniform momentum.Typical flow process of large depth open channel is mainly divided into threelevels of vortex scales. Compared with turbulent motion is composed of infinitemulti-scale turbulence vortex in the classical turbulent theory, its further reveals thereal turbulent motion mechanism.