Discussion: “Kaplan Turbine Blade-Operating Mechanism Without Oil Head” (Sproule, R. S., and Smallridge, C. G., 1965, ASME J. Eng. Power, 87, pp. 301–304)
The traditional operating mechanism of Kaplan turbine blades involves an external power supply transmitted to the runner hub by oil pressure. In the Carillon turbines the only connections to the hub are a flexible electric cable and a mechanical valve-operating rod. Elimination of the oil supply lines has been achieved by reducing the power requirement for moving the blades, by use of roller bearings and slow blade operation, and by providing suitable means of energy conversion within the hub. The paper describes the mechanism used and gives first field data on blade torques.
The paper deals with the analysis of the crack detected in the Kaplan turbine blade. In order to keep the blade integrity the sample was removed by using small sample method. Fractographic and metallographic analyses were used to determine the cause of a detected crack appearance and propagation. The material of the turbine blade was made in 1937 and its structure containing numerous eutectic sulphide inclusions corresponded to the steelmaking technology of that time. Numerous occurrences of sulphide inclusions and sulphide eutectics were identified as the main cause of material failure. Regardless of these non-metallic inclusions the blade was repaired by welding and nowadays the repaired blade has been under safe operation for more than 9 years.
Discussion: “Kaplan Turbine Blade-Operating Mechanism Without Oil Head” (Sproule, R. S., and Smallridge, C. G., 1965, ASME J. Eng. Power, 87, pp. 301–304)