Water Turbines: A New Phase of Technological Advancement

  February 13, 2024   Read time 5 min
Water Turbines: A New Phase of Technological Advancement
In France, the design of waterwheels had been given considerable attention at the beginning of the nineteenth century, but there was always a search for greater efficiency.

J.V.Poncelet had taken the old form of vertical undershot waterwheel which had straight blades or floats made of wood and set radially, and by curving the blades and constructing them of metal, had produced much greater efficiency. By using tight-fitting masonry walls and floors in the wheel pits, he ensured that all the water would be swept into the space between the blades. He used formulae to determine the size of the floats in relation to the wheel and the water flow. A further vital point, particularly with an undershot wheel, was that the water flowing out of the floats fell clear of the wheel so that it did not run in tail water.

This interest in waterwheel performance led to the first viable turbine designs being produced in France: it is significant that the south of France, Spain and Portugal had large numbers of water-driven corn mills in which the waterwheel ran horizontally, often forced round by a jet of water. Benoît Fourneyron produced a successful water turbine in 1827, and the design of other water turbines was proceeding in Germany and in the United States, but not in Britain where the waterwheel designs were reaching their peak. The Fourneyron turbine consisted of an inner fixed ring of curved gates set in one direction, and an outer ring, which had curved blades set in the opposite direction, mounted on the drive shaft of the mill or factory.

The water flowing into the fixed ring was controlled by a circular iron hatch which moved up and down in the water to control the flow. The water flowed over the gate and through the fixed gates to impinge on the rotating outer ring of blades, and thereby revolve it at a considerable speed; thus a small turbine could produce more power at greater speed, using less space than the equivalent waterwheel. The Macadam brothers of Belfast, Northern Ireland, produced a very efficient version of the Fourneyron turbine, of which the preserved example from Catteshall paper mill in Godalming, Surrey, is typical. The stator (fixed inner ring) and rotor (rotating outer ring) each have fortyeight vanes, and the inside of the stator is 2.5m (8ft 3in) in diameter. The Catteshall turbine developed 37kW (49.6hp) at approximately 25rpm, and in 1870, when it was built, it was among the biggest then in use. The principle of the Fourneyron is that of an outwardflow reaction turbine.

In England, between 1734 and 1744, an invention called the Barker’s Mill was introduced. In this water is led into a vertical tube, which rotates, and at the bottom of this tube two arms project which have nozzles at their tips. As the water flows, so the jets spout out at the ends of the arms, and the whole is pushed round by the reaction of the jets against the pressure of the air. While one or two examples of this are known, such as that at the Hacienda Buena Vista at Ponce, in Puerto Rico, it must have been hopelessly inefficient. James Whitelaw took the principle of the Barker’s Mill, improved the shape of the arms and introduced the water from below, to give a much more efficient machine known as the Scotch turbine. The arms were in the form of an elongated ‘S’ with the inlet pipe in the centre. The new shape induced a better flow out of the nozzles at the ends of the arms. The Whitelaw turbine had governors to control the speed of rotation. After 1833, when Whitelaw built his prototype, several of these were installed in factories in Scotland. One example is quoted as having 1491.4kW (200hp) with a fall of 6.7m (22ft) and a speed of 48rpm. Escher Wyss & Co. of Zurich installed Whitelaw turbines in 1844, and these were up to 45kW (60hp).

James Thomson trained as an engineer in the works of Sir William Fairbairn and became a professor in Belfast. In 1846 he was at work on the design of a new form of turbine which, when tested in 1847, worked at one-tenth of a horse power at an efficiency of some 70 per cent. He went on to patent this turbine in December 1850. Described by its inventor as a Vortex turbine, it was an inwardflow turbine in which the water came into the casing and was taken through a spiral path to be discharged through gates on to the rotor. At the same time J.B. Francis was working on a similar arrangement in Lowell, Massachusetts, which he called a centre-vent turbine. His work was published in Lowell Hydraulic Experiments. He was associated with Uriah A.Boyden in producing the Boyden turbine which was an adapted Fourneyron, designed for the particular needs of the Lowell cotton mills, and the horse-power results were extremely good. In 1854, the Merrimack Company’s mills had Boyden turbines of 2.75m (9ft) diameter which generated 522kW (700hp) under a 10m (33ft) head.

Meanwhile, the development of other turbines was proceeding in France, owing to a lack of coal to power steam engines, and in Switzerland and Germany. The ability to use a high head of water, as one would get in Switzerland or Germany, led to the design of other forms of turbine. The most famous of these high-head turbines, requiring only a small flow, is the Pelton wheel. This is an impulse wheel, patented in 1880, in which a jet of water is focused on to a bucket on the diameter of a small wheel. The bucket is cast in the form of two cups which receive water equally when it comes out of a jet at a tangent to the wheel. The water is turned back on itself as the bucket moves forward. The Pelton wheel can achieve high speeds and is easily controlled by the amount of water allowed out of the nozzle which opens or closes the size of the jet. On the Coniston Fells in Cumbria there was a Pelton wheel made by Schram and Marker of London, 0.6m (2ft) in diameter with approximately a 150m (500ft) head, which drove the air compressor in the slate quarries high up on the fell.

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