Performance measurements on a Pelton turbine model

Pelton hydraulic turbines are impulse-type turbomachines commonly used in hydroelectric plants with medium-to-high water head and in various energy recovery applications. The aim of the present work is to provide detailed performance measurements on a Pelton turbine model, along with the design and geometrical dimensions of its runner/buckets and injectors. Such a complete set of data would be useful for further development and evaluation of numerical modelling tools of the complex unsteady free-surface flow developed in the turbine, and is missing from the literature. The two-nozzle Pelton model was designed using standard guidelines and was fully constructed in the Laboratory of Hydraulic Turbomachines, NTUA. The measurements include the net water head and flowrate, the injector characteristic curves, and the torque and rotation speed of the runner, from which the corresponding overall efficiency and shaft power are computed. The model was tested with one injector (upper or lower) and with both injectors in operation, using either constant or variable rotation speed mode. The comparative results were satisfactory and in line with the theory, verifying similarity and repeatability, and allowing for an estimation of mechanical losses. The measurements covered the entire operation range of the turbine, in order to draw complete hillcharts for various operation modes.