2.1. Pelton turbine
Pelton turbines function by directing one or more jets of water tangentially onto a runner with split buckets, as shown in Fig. 1. The jet of water causes a force on the buckets, causing the buckets to rotate, resulting in torque on its shaft . After propelling the buckets, the water falls into the tailrace, ideally with almost zero remaining energy. This type of turbine Q-VD(OMe)-OPh usually used for higher head installations, but some manufacturers do supply small turbines for low head applications.
Fig. 1. Typical Pelton turbine  used with permission of IT Power Limited.Figure optionsDownload full-size imageDownload as PowerPoint slide
2.2. Cross-flow turbine
Cross-flow turbines are constructed with two disks joined together using inclined blades. Water enters the turbine from the top and passes through the blades twice, as shown in Fig. 2. After hitting the blades twice, the water ideally has almost no residual energy and falls into the tailrace . Thornbloom et al.  consider an accurately designed cross-flow runner as one in which ‘the water impinges on the top blade, is turned by the blade, and flows through the runner, just missing any shaft in the centre and impinges on a lower blade before exiting to the tailrace’.