William John Macquorn Rankine

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William John Macquorn Rankine (July 5, 1820 - December 24, 1872) was a Scottish engineer and physicist. He was a founding contributor, with Rudolf Clausius and William Thomson (1st Baron Kelvin), to the science of thermodynamics. Rankine developed a complete theory of the steam engine and indeed of all heat engines. His manuals of engineering science and practice were used for many decades after their publication in the 1850s and 1860s. He published several hundred papers and notes on science and engineering topics, from 1840 onwards, and his interests were extremely varied, including, in his youth, botany, music theory and number theory, and, in his mature years, most major branches of science, mathematics and engineering. He was an enthusiastic amateur singer, pianist and cellist who composed his own humorous songs. He was born in Edinburgh and died in Glasgow, a bachelor.

W J M Rankine
W J M Rankine

Contents

[edit] Early life

Born in Edinburgh to British Army lieutenant David Rankine and Barbara Grahame. Rankine was initially educated at home owing to his poor health but he later attended Ayr Academy (1828-9) and the High School of Glasgow (1830).

In 1836 Rankine began to study a spectrum of scientific topics at the University of Edinburgh, including natural history under Robert Jameson and natural philosophy under James Forbes. Under Forbes he was awarded prizes for essays on methods of physical inquiry and on the undulatory (or wave) theory. During vacations, he assisted his father who was manager (but also effectively engineer and treasurer) of the Edinburgh and Dalkeith Railway. He left the University of Edinburgh in 1838 without a degree (which was not then unusual) and, perhaps because of straitened family finances, became an apprentice to Sir John Benjamin Macneill, who was at the time surveyor to the Irish Railway Commission. During his pupilage he developed a technique, later known as (Rankine's method), for laying out railway curves, fully exploiting the theodolite and making a substantial improvement in accuracy and productivity over existing methods. In fact, the technique was simultaneously in use by other engineers.


The year 1842 also marked Rankine's first attempt to reduce the phenomena of heat to a mathematical form but he was frustrated by his lack of experimental data. At the time of Victoria's visit to Scotland, he organised a large bonfire constructed on Arthur's Seat, constructed with radiating air passages under the fuel. The bonfire served as a beacon to initiate a chain of other bonfires across Scotland.

[edit] Thermodynamics

[edit] Work

Image:Boltzmann's-equation.jpg To understand the significance of Rankine's work in the context of the development of thermodynamics, see timeline Edit

Undaunted, he returned to his youthful fascination with the mechanics of the heat engine. Though his theory of circulating streams of elastic vortices whose volumes spontaneously adapted to their environment sounds fanciful to scientists formed on a modern account, by 1849, he had succeeded in finding the relationship between saturated vapour pressure and temperature. The following year, he used his theory to establish relationships between the temperature, pressure and density of gases, and expressions for the latent heat of evaporation of a liquid. He accurately predicted the surprising fact that the apparent specific heat of saturated steam would be negative.

Enboldened by his success, he set out to calculate the efficiency of heat engines and used his theory as a basis to deduce the principle, that the maximum efficiency of a heat engine is a function only of the two temperatures between which it operates. Though a similar result had already been derived by Rudolf Clausius and William Thomson, 1st Baron Kelvin, Rankine claimed that his result rested upon his hypothesis alone, rather than upon Carnot's theory or some other additional assumption. The work marked the first step on Rankine's journey to develop a more complete theory of heat.

Rankine recast the results of his molecular theories in terms of a macroscopic account of energy and its transformations. He defined and distinguished between actual energy which was lost in dynamic processes and potential energy by which it was replaced. He assumed the sum of the two energies to be constant, an idea already, although surely not for very long, familiar in the law of conservation of energy. From 1854, he made wide use of his thermodynamic function which he later realised was identical to the entropy of Clausius. By 1855, Rankine had formulated a science of energetics which gave an account of dynamics in terms of energy and its transformations rather than force and motion. The theory was very influential in the 1890s.

Energetics offered Rankine an alternative, and rather more mainstream, approach, to his science and, from the mid 1850s, he made rather less use of his molecular vortices. Yet he still claimed that Maxwell's work on electromagnetics was effectively an extension of his model. And, in 1864, he contended that the microscopic theories of heat proposed by Clausius and James Clerk Maxwell, based on linear atomic motion, were inadequate. It was only in 1869 that Rankine admitted the success of these rival theories. By that time, his own model of the atom had become almost identical with that of Thomson.

As was his constant aim, especially as a teacher of engineering, he used his own theories to develop a number of practical results and to elucidate their physical principles including:

  • The Rankine-Hugoniot equation for propagation of shock waves, governs the behaviour of shock waves normal to the oncoming flow. It is named after physicists Rankine and the French engineer Pierre Henri Hugoniot;
  • The Rankine cycle, an analysis of an ideal heat-engine with a condensor. Like other thermodynamic cycles, the maximum efficiency of the Rankine cycle is given by calculating the maximum efficiency of the Carnot cycle;
  • Properties of steam, gases and vapours.

The history of rotordynamics is replete with the interplay of theory and practice. Rankine first performed an analysis of a spinning shaft in 1869, but his model was not adequate and he predicted that supercritical speeds could not be attained.

He proposed the Rankine temperature scale in 1859.

[edit] Other work

He served as regius professor of civil engineering and mechanics at the University of Glasgow from 1855 until his death in 1872, pursuing engineering research along a number of lines in civil and mechanical engineering.

Rankine was instrumental in the formation of the 2nd Lanarkshire Rifle Volunteer Corps at Glasgow University in July 1859, becoming Major in 1860 after it was formed into the first company of the 2nd Battalion, 1st Lanarkshire Rifle Volunteer Corps; he served until 1864, when he resigned due to pressure of work - much of it associated with Naval Architecture.

[edit] Civil engineering

Rankine made contributions to:

[edit] Naval architecture

Rankine worked closely with Clyde shipbuilders, especially James Robert Napier, to make naval architecture into an engineering science. Rankine was a member of the board of enquiry into the sinking of the HMS Captain.

[edit] Honours

[edit] Important works

[edit] Books

  • Manual of Applied Mechanics, (1858);
  • Manual of the Steam Engine and Other Prime Movers, (1859);
  • Manual of Civil Engineering, (1861);
  • Manual of Machinery and Millwork, (1869).

[edit] Papers

  • Mechanical Action of Heat, (1850), read at the Royal Society of Edinburgh;
  • General Law of Transformation of Energy, (1853), read at the Glasgow Philosophical Society;
  • On the Thermodynamic Theory of Waves of Finite Longitudinal Disturbance, (1869)

[edit] External links

[edit] See also

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