Experimental studies of the jet of a Pelton turbine

The jet discharged from the nozzle of a Pelton turbine is a key item of such hydropower systems and its precise shape and position are highly relevant to the optimum design of the turbine buckets to match the incoming flow. Experimental investigations, primarily with laser Doppler anemometry, have been used to identify the important fluid dynamic structures of the jet and its free surface. It is shown that weak secondary flows generated by the bends or bifurcations in the distributor of the Pelton turbine system are still present in the jet leaving the injectors. These cause small flow disturbances which affect the shape, orientation, and the topology of the jets and lead to a shift of the jet core from the axis of the nozzle.