DÉRIAZ

SWITZERLAND (see also List of Individuals)

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17.10.1895 Conches/CH - 26.5.1987 Veyrier/CH

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Paul Dériaz graduated in 1921 from ETH Zurich as a mechanical engineer. He then stayed for a while as assistant at the Institute of Hydraulic Machinery to follow in 1922 an invitation to the English Electric Company EEC to Rugby UK to set up the water turbine section. He served there as engineer and later chief engineer until retirement in 1960. He there designed conventional turbines for hydraulic schemes in Scotland, Wales, Spain, Portugal and Canada. In the 1950s he developed the reversible pump-turbine, with the first prototype installation at the Canadian side of the Niagara Falls power plant. Dériaz returned in 1961 to Geneva.

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The trend towards higher-head Kaplan turbines in excess of 60 m head was obvious as the hydropower potential was increased after World War II. With the conventional, axially arranged Kaplan turbine the runner hub would have become so large and the vanes so narrow that an appreciable loss in turbine efficiency resulted. The logical step was to revert to the mixed flow arrangement of the Francis turbine, resulting in the Francis turbine with movable blades, the so called Dériaz turbine. Instead of being at right angles to the shaft axis, the axes of the runner vanes are inclined to it, so that the hydraulic limitations of the Kaplan turbine for high heads are overcome. The Dériaz turbine applies for heads up to 200 m, with an efficiency in excess of 92%. It can also be adopted as a reversible pump turbine. Its first installation was in the Sir Adam Beck 2 pumped storage power station of the hydroelectric power commission of Ontario, Canada, where six units were installed in the late 1950s. All the design and research work for this particular installation was done in Britain.

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_{Anonymous (1961). The Dériaz reversible pump-turbine. Engineering 191: 226-228. P}

_{Dériaz, M.G. (2001). Paul Dériaz. Personal communication. P}

_{Dériaz, P. (1955). La turbine-pompe réversible axio-centrifuge à pas variable. Bulletin Technique de la Suisse Romande 81(21/22): 382-387.}

_{Dériaz, P. (1958). A comparative study of Kaplan and Dériaz turbines. Spotlight 23(2): 1-7. Dériaz, P., Warnock, J.G. (1958). Economic advantages of variable pitch runners for water turbine pumps. World Power Conference Montreal A(2): 1-19.}

_{Dériaz, P., Warnock, J.G. (1959). Reversible pump-turbines for Sir Adam Beck-Niagara pumpinggenerating station. Trans. ASME 58(A108): 1-9.}

_{Warnock, J.G. (1958). The Deriaz turbine - A Canadian achievement in turbine development. Engineering Digest 4(3): 27-29.}