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Centenary of the Water Turbine (1927)

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From the Western Mail, Friday 10 June 1927

CENTENARY OF THE WATER TURBINE.
By PROFESSOR F. BACON (Professor of Engineering at Swansea University College.)

'A ceremony has been arranged to take place in Paris to-morrow at which engineers will be invited to celebrate the centenary of the invention by Fourneyron of the water turbine which bears his name. It is possible to distinguish earlier attempts by Borda and others to construct water wheels embodying curved vanes for changing the direction of the water in the course of its passage through the wheel; but there can be little doubt that Fourneyron is entitled to be regarded as the father of the water turbine. His turbine was the first to achieve notable and sustained success and provided the foundation on which all subsequent improvements in the design of reaction type water turbines have been based.

'EARLY WATER WHEELS.
The use of water power for industrial purposes dates back to very ancient times. Crude current wheels were familiar to the Chinese on the Yellow River and the Hamites on the Nile and Euphrates fully three thousand years ago. These wheels operated entirely by the kinetic energy of the moving water, and the power thus obtained was utilised for raising the water of the rivers for irrigating the arid land and also for grinding corn and other simple applications. Similar current wheels, although necessarily of improved design. have been widely utilised and, while very inefficient, are still used for minor works designed for irrigation and other purposes in many countries.

'The first radical change in the art was the use of channels, by which the water could be conducted and directly applied to undershot wheels. This improvement resulted in the utilisation of some 30 per cent. of the theoretical water power, and the system maintained its prominence until almost the middle of the eighteenth century, when the overshot wheel was invented by John Smeaton, who showed that if the bucket wheel was changed into an overshot form, its useful efficiency would be increased to over 60 per cent. In this type of wheel the energy of the water was applied directly through its weight by the action of gravity and yielded a very high efficiency. Overshot wheels were formerly built of great size. One at Laxey, Isle of Man, constructed about 1865 and said to be still in operation, is 72 feet 6 inches in diameter and develops 150 horse-power. A number of overshot wheels are also in use at old mills in the Catskill Mountains in New York State.

'The breast wheel which followed the overshot wheel, was developed in England during the latter part of the eighteenth century and was used for a great number of years. It consisted of a circular drum, having on its periphery a series of buckets, the sheathing of the drum forming their bottom. They were operated partly by gravity and partly by kinetic energy and the water was applied through a flume and controlled by the gates. `Below these was located the 'breast " which consisted of a concave cylindrical surface of planking, concentric with the wheel. The clearance was very small, thus preventing the water from spilling out of the buckets until it had reached the lower level. This type of wheel gave an efficiency of about 70 per cent.

'FOURNEYRON'S TURBINE.
Benoit Fourneyron, the memory of whom is being honoured in Paris to-morrow, was a Frenchman, who began his experiments on water turbines when only 21 years of age. After four years of endeavour his first turbine was erected at Pont Sur l'Ohnon in France. His efforts were apparently stimulated by the desire to win a prize for an improved water motor offered by the Societe d'Encouragement in the quest of which he he was eventually successful. Ten years later, Fourneyron erected a turbine at St. Blaise, in Switzerland, which operated under a head of 354 feet. A model of this turbine is to be seen in the Science Museum, South Kensington. The machine consists of a vertical cylindrical chamber with a side inlet for the water, and a central pipe below through which the water passes to an annular outlet at the base of the pipe. This outlet is fitted with thirty guide blades which direct the water in a tangential course as is escapes. Surrounding this passage is a wheel keyed to a vertical shaft and provided with vanes between which the water flows as it passes from the inner to the outer circumference, where it is finally discharged.

'The toe of the shaft is carried in a special bearing having oil supplied under pressure, and the power given off by the shaft is transmitted by bevel gear at the upper end. The central pipe containing the guides is carried by three screwed rods connected above by gearing by which the pipe can be accurately raised so as to contract the supply passage into the wheel if less than full power is required. The water under pressure is discharged in a tangential direction from the fixed guides, and on passing between the vanes of the enclosing wheel has its direction of motion gradually changed. By the time the water reaches the outer rim practically all its velocity of whirl has been transferred to the moving wheel. The inner and outer diameters of the wheel of the original Fourneyron turbine installed at St. Blaise in 1837 were approximately 7 1/2 inches and 13 inches respectively, and the turbine is said to have developed 30 effective horsepower at 2,300 revolutions per minute. It is not a little remarkable to learn that such high speeds were employed with some degree of success nearly a century ago. Naturally bearings and gearing gave trouble and it is not surprising to learn that the Fourneyron turbine was afterwards replaced by tangent wheels, and at a still later date by Girard impulse type turbines.

'Nevertheless, the Fourneyron turbine was used extensively in Europe under conditions better suited for its use right up to the beginning of the present century. Moreover, the first two turbines of 5,000 horsepower installed at Niagara in 1895 were of Fourneyron type.

'MODERN WATER TURBINES.
The inward-flow wheel, in which the action of the Fourneyron turbine is reversed, was patented by S. B. Howd, of Geneva. N.Y., in 1836, and seems to have been the origin of the American type of turbine. Very great improvements were made, however, in the construction by James B. Francis about 1847, and many regard him as the originator. The Francis turbine of to-day has displaced all other types of reaction turbines and, with its rapid development, radical departures have been made from the strictly radial inward-flow, with the result that the Francis turbine of to-day is of a combined radial or diagonally inward discharge type. A transition period in the design of turbines occurred between 1890 and 1900 when the turbine was being modified to meet the requirements of electric generator drive, one phase of this transition being an increased complexity marked particularly by the adoption of the multi-runner units.

'Another change took place in 1911 and 1912 marked by the return to greater simplicity and the re-adoption of the single runner vertical turbine. This period also marks the introduction of the metal speed ring built into the concrete sub-structure, in combination with a concrete volute casing. Since that time this construction has been universally adopted as standard practice for vertical units under low head and moderate heads.

'After having remained practically stationary in its development for a number of years, the design of reaction turbines has shown a surprising number of changes and improvements within the last four or five years. The introduction of the propeller type of runner, and of the hydraucone and spreading types of draft tubes, etc., has thus made possible the extension of the range of available speeds, so that extremely high specific speeds are now obtainable with satisfactory efficiency. One of the most remarkable recent innovations in water turbine construction is that due to Professor Kaplan. The distinguishing feature of the Kaplan turbine is that the angle of the runner is adjustable, being built on the lines of a screw propeller with feathering blades. The advantage of this is that a high efficiency can be maintained over a very large range of load under varying head.

'A Kaplan turbine developing 10.000 horse-power at 62 1/2 r.p.m. under the low head of 21 feet has recently been installed by the Swedish Government at Lilla Edet. In dimensions it is one of the biggest turbines ever built. The runner has a diamter of 19 feet 8 inches and weighs 62.5 tons. The flow of water through the turbine amounts to 5,700 cubic feet per second.

'Official tests just published show efficiencies reaching 82.8 per cent. and remaining over 90[?] per cent. all the way between full and half load.'