conversion. In the reaction turbine, the fluid fills the blade passages, and the head
change or pressure drop occurs within the runner. An impulse turbine first converts the water
head through a nozzle into a high-velocity jet, which then strikes the buckets at one position as
they pass by. The runner passages are not fully filled, and the jet flow past the buckets is
essentially at constant pressure. Impulse turbines are ideally suited for high head and relatively
low power. The Pelton turbine used in this experiment is an impulse turbine.
The Pelton turbine consists of three basic components as shown in Figure 1: a stationary
inlet nozzle, a runner and a casing. The runner consists of multiple buckets mounted on a
rotating wheel. The jet strikes the buckets and imparts momentum. The buckets are shaped in a
manner to divide the flow in half and turn its relative velocity vector nearly 180°.