The Jonval turbine is a water turbine design invented in France in 1843, in which water descends through fixed curved guide vanes which direct the flow sideways onto curved vanes on the runner.[2] It is named after Feu Jonval, who invented it.[2] The Jonval incorporated ideas from European mathematicians and engineers, including the use of curved blades, which gave it triple the efficiency of a water wheel.[3] This new turbine failed to satisfy the public interest in seeing the water wheels in action, which was likely was accepted as a minor drawback at that time.[4]
This type is efficient at full gate, but at partial gate it is less efficient than a Francis turbine.[5] The usual orientation of the wheel was horizontal and the first devices were even alternatively named as "horizontal water wheels". However some sources mention turbines with both vertical and horizontal shafts.[6]
N.F. Burnham, an American turbine manufacturer, patented numerous improved designs in the second half of 19th century. His turbines had greater efficiency than the Jonval, especially at partial gate, and fewer maintenance problems.[7]