Study On Dynamic Stress Of Blade Of Hydrodynamic Turbine

With the increasing of capacity of hydrodynamic motor generator, water turbine's blade run in villainous environment. It isn't advantageous to the safety of the blade. So it is necessary to improve the intensity and running safety of the blade.To this problem, on the basis of the work property and characteristics of the water turbine's blade. The finite element mechanics model of blade vibration characteristic is described with the eight- node three-dimensional nonconforming and all parts of blade damp are analysised, the calculating model of blade damp is built, the tackling method of blade damp in calculating of dynamic stress is presented. On the basis of the complexity of flow-field of turbine, the acting force of the blade supported is abbreviated. Therefrom, the finite element movement equations of moving characteristics of blade is derived and the finite element movement equations of vibration characteristic is gained. Finally, the mode superposition method is used to calculate the displacement and stress responses of the blade.Founding on the theory above, the FEM program which adopt the blade dynamic stress analysis is developed. In this program, the wave propagation technique is employed. The number of degrees of freedom is reduced and the cost is greatly decreased. It has been verified that the program can predict the vibration characteristics of blade accurately. The result obtained is very satisfactory. Owing to the large generality of three-dimensional solid elements, the FEM program based on this model can be applied extensively on the analysis of vibration characteristics of the elastic continuum.