engleski

FATIGUE DAMAGE AND REPAIR OF THE REVERSIBLE HYDROPOWER FRANCIS TURBINE

The Francis turbine/pump of the reversible hydropower plant represents particular problem in the design, repair and lifetime prediction. Extreme loadings, during the swift from the turbine to the pump regime of exploitation, cause the damage that is not common in the case of the Francis turbines of standard hydropower plans. Repair of such damages requires detection of the fracture propagation scenario, modification of the blade junction geometry, development of welding process strategy and evaluation of the welding process parameters.On the particular engineering problem, i.e. the 14.8 tons turbine characterized by the 155 MW of maximum power, 600 rpm, and flow of 20.5 m3/min, the cause detection, as well as the repair method is described.The numerical simulation enabled the detection of failure scenario, as well as the approval of proposed method for reducing the stress concentration parameters. Evaluation of the welding process parameters for the cast CrNi alloy, together with the thermal treatment of the welded joints are described as well. Strategies, parameters and conclusions that are going to be presented in the paper, are explaining some important aspects of the hydropower technology and repair strategies.

Francis turbine; Fatigue damage; Welding repair

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