Inlet flow conditions and the jet impact work in a Pelton turbine

Abstract

The inlet flow of the jet entering the rotating buckets of a Pelton wheel turbine is considered with respect to jet flow impact and the non-disturbing flow condition. In the first step the volume rate of flow in the rotating frame of reference is shown to be independent of the bucket rotational position. Next, kinematical distinctions are made between the inlet flow at the bucket cut-out and inlet flow at the bucket splitter. Then, based on calculations of the impact forces and the corresponding impact work, the percentage of total jet impact energy is estimated. For purposes of configuring the proper inlet flow, the non-disturbing flow condition is specified and the corresponding criterion for geometry layout of the bucket is shown to be a function of the Pelton wheel turbine specific speed.