Francis Unit Hydraulic Vibration And Destruction Of Reason Analysis

With the increase of unit capacity,size and speed in modern greathydropower sets,the analysis of vibration problem in design and operationbecomes more and more important.This paper elaborates on vibration problem of the hydropower setsduring its operation,at present through a great deal of research work onthe experiments and the analysis of the draft tube pressure pulse on themodel or machine throughout the world,it has analysed the low-frequen-cy pressure-pulse caused by the water folw in the draft tube and has sug-gested the improving measurements correspondingly on the damages ofthe draft tube in the 2~# set in Ankang hydropower station.There are damages generally in varying degrees during the operationof the runner cover with the same type of Ankang-hydropower station.This paper firstly has adopted the world leading finite element analysisprogram and has made the stress and strain analysis on the structure ofthe runner cover. With the combination of the actual working situation,ithas simulated the water force pulse of the sets and has also analysed thedamage causes of the runner cover. Finally,it has drawn the condisionwhich is the same as the actual damages and has made the correspendingpromoting-measurements which are of great significance.Through the on-site tests of the stability in Ankang hydropower sta-tion and with the frequency anlalysis of the data collected,it has attainedthe conclusion that the reasons of vibration in 1~# set are mainly caused bythe water forces and has made the measurements of the elimination andthe decrease of the vibration...