Flow dynamics of the free surface flow in the rotating buckets of a Pelton turbine

The relative flow in the rotating buckets of a Pelton turbine was calculated with respect to the influences of centrifugal, Coriolis, and impact forces. Based on the assumption of frictionless flows, the so-called invariance equation was presented, which enables the changeable flow velocity in a rotating bucket to be calculated. The introduced jet layer method relying on the invariance equation significantly simplifies the computation of the entire jet expansion in the rotating bucket. For purely radial flows, contributions of centrifugal, Coriolis, and impact forces to the power exchange and the corresponding effectiveness relations were quantified. In general, the centrifugal force only performs the negligible work, if compared with the effectiveness of the Coriolis and the impact forces. Various calculation examples were presented to show the flow development and the effectiveness of all active forces in the rotating bucket and to explain the application of the invariance equation. The results presented in the article for frictionless flows can be applied as the reference for further computational and experimental investigations with respect to the flow friction effects on the hydraulic efficiency of a Pelton turbine.

Information for the Spatial Factor in Korte's 3rd Law of Apparent Motion

The experiments reported here show that Korte's space-time invariance equation governing perception of apparent motion is limited to situations in which metric or apparent separation of targets define but a single interval of space. Variation in interstimulus intervals and metric separation of targets did not influence the perception of apparent motion when the background array was structured to depict apparently equal intervals of space. These results provide a test of Koffka's and more recently Gibson's view that higher order properties of intervals of space specify the spatial factor in apparent movement.