The breastshot waterwheel: design and model tests

By: G. Muller and C. Wolter

The waterwheel is one of the oldest hydraulic machines known to humankind and has been in use since antiquity. Originally built of wood, the availability of new materials, namely wrought iron, and the increasing demand for mechanical power during the industrial revolution led, in combination with the development of hydraulic engineering, to the rational design of waterwheels, resulting in much increased performance and efficiency. Three distinct types of waterwheels evolved: the overshot, the breastshot and the undershot wheel.

Overshot wheels were investigated quite thoroughly and were found to have efficiencies of more than 85% for a broad range of flowrates from 0.2 to 1.0 Q/Qmax. Only one measurement of an undershot or Zuppinger wheel is known to the authors. Researchers from the Technical University of Stuttgart in 1977 measured the efficiencies of a 42 kW Zuppinger wheel which was built in 1886 and had been in continuous operation since. The measurements showed efficiencies of 71–77%. The breastshot wheel however, which was particularly popular in Britain,was never investigated. Read more