Model Test Study Of Francis Pump-turbine Runner Stress

To enhance the reliability and security of the electric grid,the capacity of storage power plant is necessary to increase in the grid.Nowadays the storage plant is rapidly developing in our country.As the most important component of the plant,its developed trend is higher head and bigger capacity for pump turbine,which results in the increase of unit dimensions.And runner blade becomes more length.At the same time,consideration of as the unit operation mode converting frequency and complexity of the unit load,the fatigue strengthen is hard to guarantee if designed inappropriately.Bashed on the research of runner blade stress measuring method and combined the remote measure technology which developed recently,it is developed a 32 channnels stress measuring system for pump turbine runner blade.For the transducers installation research,three wire arrangement methods are compared and its resisting water scouring test is carried out.Finally the wire arrangement and protection method is determined.It is suggested that 32 stress measuring transducers distribute on 10 most dangerous locations of 9 runner blades based on experiences.Model test investigation conditions include turbine model,pump model,pump bump zone and “S” characteristic zone.When measuring the runner blade stress,pressure fluctuation signal of the whole water passage is recorded at the same time to study the interaction between rotating and stationary components.After finished the model turbine investigation,model test data is detained analyzed.Stress analysis includes dynamic stress and static stress distribution,the relation between dynamin stress and pressure fluctuation and the relation between dynamic stress and static stress.And the most dangerous zone is determined by spatial distribution for turbine model,pump mode,bump zone and “S” characteristic zone.For above conditions,the dependence of stress on load is also researched.It is a key research content of runner blade stress study of big storage power units for hydropower plant security protection.And it is essential for the unit security and stability operation.This paper is based on the runner blade stress measurement and analysis for 500 m head range pump turbine.And it can provide technical support for pump turbine development at this range.