Abstract: Runner’s temperature field and stress field during the period of welding are simulated on the basis of attaining simplified model of Francis turbine runner, realizing the thermal source loading of multi-pass welding and solving the problem of conduction between independent entities. Thermal cycle curves of different striking places, evolvement process of longitudinal stress and residual stress field after welding are obtained. The simulation result shows that maximal welding stress appears along the adjacent area between blades and bands or blades and crown. The result can explain why fatigued crack on the turbine runner’s blade appears and extends.

Key words: Blade, Runner, Stress field, Temperature field