A Deriaz turbine is a type of water turbine similar to a Kaplan turbine but which has inclined
blades to make it more suitable for higher heads.
It is particularly suitable for the head range between 20 meters and 100
meters – a window of operation between that of the Kaplan and Francis
turbine. Because the runner blades are adjustable, the Deriaz design
offers a number of other advantages: (1) smooth and efficient operation
over a wide range of head and load; (2) uniform distribution of pressure
and load across the blade (i.e., from the casing to the mid-span to the
hub); (3) freedom from development of cavitation across the entire operating
|Vertical Deriaz turbine
Hokkaido Electric Power Co. / Takami Power Station
The Deriaz turbine is classified as a double-regulated, reaction, mixed-flow
turbine. It is named after its inventor Paul Deriaz, a hydraulic designer,
and was the first kind of diagonal turbine to be developed. An early major
Deriaz turbine system was installed at plants on both the Canadian and U.S.
sides of Niagara Falls.