Deriaz turbine

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Last updated

June 25, 2026

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The Deriaz turbine is a type of reaction turbine that uses a mixed-flow design, meaning water enters radially and discharges axially. It is characterized by swiveled, variable-pitch runner blades that improve efficiency, especially at partial loads in medium-sized machines. This design has proven useful for higher heads and some pumped-storage applications. A key advantage of the Deriaz turbine is its lower runaway speed compared to Kaplan turbines, which can lead to significant savings in generator costs. However, very few Deriaz turbines have been built.1

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turbine
Mixed-flow turbines
A mixed-flow turbine of the Deriaz type uses swiveled, variable-pitch runner blades that allow for improved efficiency at part loads in medium-sized machines. The Deriaz design has proved useful for higher heads and also for some pumped storage applications (see below). It has the advantage of a lower runaway (sudden…
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A mixed-flow turbine of the Deriaz type uses swiveled, variable-pitch runner blades that allow for improved efficiency at part loads in medium-sized machines. The Deriaz design has proved useful for higher heads and also for some pumped storage applications (see below). It has the advantage of a lower runaway (sudden…
Read More