Dynamic Response Analysis Of Cracked Hydropower House And Spiral Case

The vibration of large-scale Francis hydraulic turbine set, which affects the safe operation of hydropower stations, is a serious and common problem. Powerhouse vibration caused by hydraulic turbine set frequently occurs in many hydropower stations equipped with large-scale Francis hydraulic turbine set at home and abroad in varying degrees. Especially, engineers and scholars pay much attention to the vibration of floor above generator. However, up to now thorough study on the key problem of vital importance to the normal operation of those hydropower stations hasn't been carried out for its complexity.The large scale of Three Gorges hydropower station, as well as the single-unit capacity of it's hydraulic turbine generator set, is well known in the world. Yet few mature theories and practices have been made with regards to the dynamic response of cracked concrete structures. Therefore, rational estimation to the vibration of Three Gorges powerhouse quantitatively is not only a key technique problem to the construction of Three Gorges, but also a difficult and pioneer interdisciplinary subject with every promise of further. Finite element method (FEM) is adopted in the paper, and detailed and deep research on the vibration of Three Gorges powerhouse is carried out. Its primary context involves the following aspects:1 .A more realistic three-dimension model of the complex powerhouse structure is made, which includes its integral flow passage, grid structure, key holes, all galleries, etc. The concrete cracks are also considered in two modes: the centralized mode and the generalized mode.2.the natural dynamic characteristic of the powerhouse has been analyzed based on the modes above and comparison between the different results is made.3. On the basis of the measured pulsating pressure data obtained from hydraulic turbine model test, a three-dimension field of pulsating pressure in the flow passage has been constructed with reference to existing research results, and dynamic responses of the powerhouse structure has been solved under combined complex loads.4.The fatigue property of the spiral cases, fixed guide vanes and stay rings is analyzed. Results show that these parts can withstand pulsating water pressure over their lifetime at normal operational conditions.