This work presents the development and application of a new optimal design methodology for Turgo impulse hydro turbines. The numerical modelling of the complex, unsteady, free surface flow evolved during the jet-runner interaction is carried out by a new Lagrangian particle method, which tracks a number of representative flow elements and accounts for the various hydraulic losses and pressure effects through special adjustable terms introduced in the particle motion equations. In this way, the simulation of a full periodic interval of the flow field in the runner is completed in negligible computer time compared to the corresponding needs of modern CFD software. Consequently, the numerical design optimization of runner geometry becomes feasible even in a personal computer and affordable by small and local manufacturers. The bucket shape of a 70 kW Turgo model is properly parameterized and numerically optimized using a stochastic optimization software to maximize the hydraulic efficiency of the runner. The optimal runner and the rest turbine parts are then manufactured and installed in the Lab for testing. Detailed performance measurements are conducted and the results show satisfactory agreement with the numerical predictions, thus validating the reliability and effectiveness of the new methodology.

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.

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