Research On The Vibration Interaction Of Multi-unit Segments Of Hydropower House

The vibration is an important factor in the safe operation of hydropower house and its unit segments.Vibration problems are directly related to the normal operation of hydropower station and personnel safety.A lot of safety problems,which results from the vibration problem,have been generated in many domestic and international built hydropower stations and some of them had also caused significant damage.Besides that,due to the capacity of modern hydropower station is larger and larger and the water head is higher and higher,the vibration problem of hydropower station has been increasingly highlighted.Many scholars have done much work about the vibration,but there are few researches published on the vibration interaction of multi-unit segments of hydropower house.Therefore,this paper is studied based on measured data analysis and numerical simulation.The main contents and conclusions of this research are summarized as follows:(1)Based on the analysis of measured vibration data,the main reason of the vibration interaction of adjacent unit segments is the vibration whose dominant frequency are the low vibration frequency induced by draft-tube vortex band frequency and the rotation frequency of units,etc.or the vibration frequency induced by the non-uniform flow of volute.(2)The measured data of unit segments under different water heads has been analyzed.The adverse effect of intermediate water head on the vibration of adjacent unit segments is little.The adverse effect of high and low water head on the vibration of adjacent unit segments is bigger than the former.(3)The comparative analysis of numerical simulation results and measured data shows that: The induced vibration frequency by the non-uniform flow of volute is one of the important dominant frequencies.And the foundation is the main path of vibration transfer between adjacent unit segments.In addition,the low frequency in the prototype observation has also played a great role in the direction of some points and there is a little discrepancy with the numerical simulation result.By analyzing the reason of vibration effects of adjacent unit segments,in addition to the mutual transfer effects about vibration load on the foundation,the hydraulic disturbance of the adjacent draft-pipe and its downstream water is also one of the factors.(4)Through the numerical simulation of three-dimensional finite element method,we know that the effect of different material parameters on the vibration of hydropower house is different from each other.When the elastic modulus of the rock increases by 10%,the amplitude of hydropower house will decrease by 10%~12%.When the concrete elastic modulus increases by 10%,it will reduce by 2%~3%.The influence of damping ratio changes is much smaller and ever the same.Therefore,from the perspective of the effect of material parameters on the amplitude of hydropower house with the vibration load from its adjacent unit segment,there is the following relation: damping ratio<concrete elastic modulus<rock elastic modulus.