Museum officials, me, Narasiah |
Narasiah pointing to line மயிலையம்பதியான் |
PostScript, June 28: Mr Narasiah, via email, offers this translation by GU Pope, of the TirukkuraL verse mentioned above.
Museum officials, me, Narasiah |
Narasiah pointing to line மயிலையம்பதியான் |
Fundamentally, a steam turbine is a specialized steam engine, which doesn’t have a piston, but has multi stage rotors and stators. Steam engines use the pressure of the steam to move the piston – which is the mechanical work. Turbines, also utilize the velocity and pressure to do the mechanical work. High pressure steam powers rotors blades, arranged in a circle around a central axis. The steam flows through these rotors after having propelled them and goes through a set of stators, which constrict the steam thus increasing its velocity. This steam passes through a second set of rotors and stators, then a third set and so on until it no longer has significant pressure to do much mechanical work. Thus turbines are phenomenally more efficient than piston-based engines.
Compound Turbine - Flow of Steam and Working method |
Water turbines and
windmills had been in existence for centuries. But the metal blades that could
withstand the pressure of steam were far beyond the metallurgical capabilities
of any country in Europe, or even Britain its leading industrial power, until
the invention of Bessemer steel in the 1850s. The velocity of even low pressure
steam is calculated as 2500 feet per second or 1700 miles per hour. At those
speeds, centrifugal force would tear apart any metal blade used as a rotor.
Even James Watt knew this, and expressed it thus when his partners wondered if
their business would face competition from steam turbines: “Without God makes
it possible for things to move at 1000 feet per second, it cannot do much harm.”
Bessemer steel and improvements in metallurgy and science changed that. In 1882, Gustaf Patrick de Laval made an impulse steam turbine. And in 1885, Charles Parsons made a small turbine producing 7.5KW. Parsons’ key insight was to slow down the speed of the jet of steam in a series of steps, each partial drop of pressure being sufficient to power rotor blades that wouldn’t fall apart under the high speed. The principle of subdividing the velocity of steam into a series of steps, so that only moderate speeds are produced, remains the basis of all efficient turbine design.
Parsons revolutionized the efficient use of steam on a scale that neither Trevithick nor Stephenson could have imagined. The power of steam was multiplied a hundredfold. It affected not merely the size and scale of transportation, but also electric power generation and other industries in unthinkable ways.
Year | Turbine Power in KW | Efficiency in % |
---|---|---|
1885 | 7 | 1.6 |
1888 | 75 | 5.0 |
1899 | 1000 | 25.0 |
1912 | 2500 | 75.0 |
I have left out the delightful
story of Parson’s ship SS Turbinia, his stunt during a naval parade, and its impact on the British Navy, and later all shipping.
Note: I edited this on September
17, 2021 by adding a few paragraphs about some components of turbine design.
References
Creating the Twentieth Century,
by Vaclav Smil
The Steam Turbine and other inventions of Sir Charles Parsons, by R.H. Parsons
Westinghouse or Tesla – who should we credit for Alternating Current : Kathy Joseph’s video