Research On Structure Vibration Of Hydropower House

The capacity and size of modern hydrogenerator set are larger with rapid developing of hydroelectric engineering, specific speed of hydraulic turbine increase too. The phenomenon of excessive vibration in some load area is founded ubiquitously. As a prominent problem, hydraulic resonance in large-sized Francis turbine not only affects the reliability of generator unit, but also arouses violence vibration of powerhouse structure. This resonance usually exceeds serviceability limit state and ultimate limit state; endanger hydropower station's economic operation, even safe operation.There is no effective method to forecast and estimate the hydraulic vibration of hydraulic turbine up to now in the world, much less research in-depth for powerhouse structure resonance excitated by hydraulic disturbance of hydrogenerator set. Based on the vibration test in Yantan hydropower house, in this paper the author adopt LES method which belong to three dimensions unsteady turbulent flow numerical analysis to simulate vibration resource characteristics of hydrogenerator set, a harmonic vibration model of powerhouse substructure is put forward to carry out firstly a precise modal analysis and dynamic response analysis for generator floor. The numerical calculation results agree well with the surveyed data in situ. Due to the success in Yantan Project, the similar method are applied in Three Gorges Project , the maximal potential vibration excitated by hydraulic disturbance of hydrogenerator set in Three Gorges hydropower house are estimated.The modal analysis, dynamic response analysis and allowable vibrationvalue for hydropower house proposed by author compose an integrated system to calculate and analyze the vibration of hydropower house, and reinforce the current design code for hydropower house.The main contents of the thesis are as listed below.In chapter 1, the existed problem and current research on vibration of hydropower house with large-sized Francis turbine generator unit are introduced.In chapter 2, some previous test data in situ and deduced conclusions of powerhouse vibration in Yantan Project are summed up.In chapter 3, the subgrid eddy-viscosity model for large eddy simulation is applied to calculate the three dimensions unsteady periodic turbulent flow in Yantan Francis turbine. The pulsating characteristics of some main physical parameters in flow field are found. The calculated axial water thrust of hydraulic turbine agrees with the model-test value. It's demonstrated that thrust bearing load of Francis hydrogenerator with down-shelf supporting structure can be regarded as maximum vertical excitation force of hydropower house vibration.In chapter 4, the model-building principle and calculating method of finite element dynamic analysis for large-sized assembled structure are discussed. The substructure model for hydropower house vibration analysis is established to obtain precise modal of generator floor. The harmonic vibration assumption is adopted to calculate house structure's dynamic response from hydraulic excitation force of hydraulic turbine generator unit. All numerical calculation results agree well with the surveyed data in situ.In chapter 5, the estimate of structure vibration in Three Gorges Project is given. Because of the similarity between hydropower house and Three Gorges hydropower house, the analysis method of Yantan Project can be usedin Three Gorges Project too. The calculating results indicate the generator floor in Three Gorges Project would occur strong vibration the same as in Yantan Project on the most disadvantageous condition.In chapter 6, the vibration design and vibration resistant constructional measure are discussed, and the powerhouse structure vibration allowed value is proposed. To make a comparison between earthquake action and vibration action, the seismic analysis of hydropower house is carried out.