Study On The Flow-induced Vibration Characteristics Of Dividing-wall Of The Dam And Its Structural Optimization

Outlet structure is an important part of hydropower project, When it discharges flood, the structure often occurs vibration dues to fluctuating pressure, which is called flow-induced vibration. In recent outlet structure, the problem caused by flow-induced vibration becomes more and more prominent because of large flow, high velocity of flow and the structure that tends to light. Such as dividing-wall, it’s frequently reported that structural vibration and damage are caused by the flow at home and abroad. Therefore, it is necessary to develop a study on the flow-induced vibration characteristics of dividing-wall when it discharges flood, and its stability will be evaluated based on the results.Bottom-flow dissipation is applied to Xiangjiaba Hydropower Station which has large unit-width discharge and high water-head, and the flow spins and rolls strongly in the plunge pool. When the dam discharges flood, because some parts of dividing-wall are submerged in the flow and the dividing-wall is affected by the water-flow of low frequency and large range, the load of dividing-wall is very complex and the problem of its dynamic responses and stability are prominent. In response to these issues, in this paper, the flow-induced vibration characteristics of dividing-wall of Xiangjiaba Hydropower Station and its structural optimization were studied by hydro-elastic model experiment and finite element simulation. The main studies are as follows:(1)A hydraulic model and a hydro-elastic model of dividing-wall of Xiangjiaba Hydropower Station were developed on basis of their simulation theories and testing requirements, the hydrodynamic loads were tested in the hydraulic model and the dynamic responses of the dividing-wall were tested in the hydro-elastic model. And the hydrodynamic loads characteristics and the results of the dynamic responses of dividing-wall were analyzed.(2)A three-dimensional finite element model for dividing-wall of Xiangjiaba Hydropower Station was established by using the finite element software-ANSYS, and the modal characteristics could be calculated to analyze that whether the dividing-wall would occur stochastic resonance with the flow. Meanwhile, the dynamic responses of dividing-wall could be calculated by adding the the hydrodynamic loads tested by model experiment to the numerical model, and the results would be improved by the method that could improve the stress results calculated by the finite element method. Comparing the calculated results of the dynamic responses that had improved with the results that were tested by hydro-elastic model experiment, and the stress and the displacement of dividing-wall were determined according to the relevant standard, the safety and the stability of dividing-wall could be evaluated. (3)Structural optimization of dividing-wall was carried out under the conditions that height and cross-sectional shape parameters were set as independent variable and reduction of the maximum tensile stress was set as optimization objective, its aim was to find a shape that was safer.