Classification and Types of Turbines

The specific choices of turbines types shown here are not meant to be complete, but only a partial introduction to classification and historically important turbines in the late 19th century. These notes are by a rank amateur - turbine engineers and technology historians no doubt will read and shudder like an unbalanced runner.

American-type turbine

Refers to a type of mixed-flow turbine built by American manufacturers from about the 1870s into the 20th century. Companies and turbines of this type include Francis, Leffel, Hercules, Risdon, Swain and others.

American-type turbines receive water which flows inward from the periphery, downwards, and then flows outwards or radially.

The figure (from Tyler, W.W., 1898.) shows why the later American turbines are “mixed-flow”: The direction of water changes as it moves through the runner.

 Direction of flow

Turbines can be classified by the general direction(s) of water flow through the runner buckets.

Francis turbine

An important type of American mixed-flow turbine invented and developed by British-born James Francis who emigrated as a young man to America (and worked briefly on the new railroad to Stonington Connecticut in 1833). Francis moved to Lowell Massachusetts and shortly thereafter became the Manager of Locks and Canals. He used a careful experimental approach to increase the efficiency of Uriah Boyden’s improved Fourneyman turbine. Francis-type turbine designs were hugely influential, widely used in the last half of the 19th century, and are still made and used today. Figure from Safford and Hamilton, 1922, p. 1253.

Fourneyron turbine

An outward flow turbine developed by French engineer Benoit Fourneyron beginning in the 1820s. An important turbine technology development since it was the first small turbine that could develop sufficient power for industrial use. The Fourneyron turbine greatly influenced the further development of modern turbines. This turbine technology was brought to the U.S. in the early 1840s and used throughout the nineteenth century. Figure from Safford and Hamilton, 1922, p. 1249.

Leffel turbine

James Leffel of Springfield, Ohio invented, developed, and manufactured turbines which were widely used through the last half of the 19th century. Leffel turbines are characterized by a series of 12 gates around the periphery of the case. The company was founded by Leffel in 1862 is still in business in Springfield, Ohio and producing turbines. Leffel turbines were also manufactured in New Haven Connecticut.  Figure from 1885 Leffel catalog.

Pelton waterwheel

 Pelton wheels are the most widely distributed and most commonly encountered type of impulse turbine. Their cast iron buckets have a characteristic tandem cup form that is credited with achieving their high efficiency. They were developed by Lester Pelton in the Mother Lode region of California in the 1870s to provide mechanical power for hard rock mining; Pelton's design achieved significant improvements in efficiency compared to other impulse wheels. In later decades Pelton wheels proved adaptable for hydroelectric power, particularly at locations with high head and low flow volume, for which purpose they have been scaled up massively to units of 100,000 HP and more. In the second half of the 20th century, improved forms of Francis turbines have displaced Pelton wheels except for installations with very high (>2,000 ft.) head.  The wooden or cast iron shroud typically found on Pelton wheels helped direct water discharge (rather than direct the inflowing water jet as on reaction wheels).

Thank you to Mike Dalbey, volunteer at Wilder Ranch State Park in Santa Cruz, CA for Pelton wheel information.

 Reaction waterwheels

Many turbine types are classified as reaction: power generation depends upon changes in water pressure acting on the turbine vanes within an enclosed case.  Reaction turbines can be contrasted with impulse turbines in which a jet of water is directed onto the runner vanes. Impulse turbines do not require an enclosed case. 

Rose Wheel

Very likely named for the inventor Timothy Rose, but believed by some to be named for the appearance of the water spraying out of the wheels when operating.

“…the cast iron scroll wheel (or rather one of them, for there were two, both set on a large wooden shaft, on the inner end of which was the saw crank-wheel.  These wheels were sometimes called "Rose wheels" as the water would fly out at each side like the blossom of a rose, when running under a "full head" of water.  The tail race of the mill runs just in front of the mill, and is the whole brook.”

From archival material at the Henry Ford Museum in Dearborn MI describing the Georgetown Massachusetts Spofford –Morse sawmill which was subsequently moved to and rebuilt at the Ford museum.  Quote is from Peterson, Charles E..  Sawdust Trail, Annals of Sawmilling and the Lumber Trade from Virginia to Hawaii via Maine, Barbados, Sault Ste. Marie, Manchac and Seattle to the Year 1860.  Bulletin of the Association for Preservation Technology. Vol. 5, No. 2, 1973. 84-153. 
 Video and photo show a pair of rose wheels at a sawmill in Rhode Island.  Machinery moved to RI from Massachusetts and assembled in the 1930s.

Scroll wheel

Also called scroll-type turbine. The figure shows a top-view cross-section of a Tyler turbine from J. Tyler US patent 20456 (1858) showing the scroll shape of the turbine case. There is typically a single gate controlling the entry of water into a scroll turbine. Blue arrows show direction of water flow in the case when the turbine control gate is open