How modern steam turbines came to be

This is the first article of a series that explores the evolution of the steam turbine from Parsons first model to the modern day turbine.

When we ask the question as to who invented and developed the modern day large steam turbine we say it must have been General Electric and/or Westinghouse. Then when we ask who invented and manufactured the first axial flow compressor we think that it no doubt was Brown Boveri Company (BBC) of Switzerland. Thirdly, when we think of who first ran nozzle tests and contemplate building an internal combustion gas turbine again we think that it must have been BBC, but in reality it was an English man by the name of Sir Charles Algernon Parsons (13 June 1854 – 11 February 1931). We owe him a great deal and he deserves our sincere thanks, respect and admiration. He gave us the steam turbine which makes today's highly efficient combined cycle possible.

I would like to present to you in this blog a condensed story of this great scientist, engineer, developer and manufacturer.  You will find it most interesting.

The Parsons/ Richardson 1911 book

My younger son, James, knowing of my keen interest in turbines, recently gave me an interesting and informative book for Christmas all about Sir Charles A. Parsons entitled, ‘The Evolution of The Parsons Steam Turbine,’ written by Sir Alexander Richardson. It was first published in March 1911 and has recently been digitally reprinted in 2014 by both the Cambridge University Press and the University of Chicago Library. The book traces the life of this extra ordinary individual from birth through the year 1911. The book is 437 pages long which includes 173 pages of not numbered drawings and photographs called plates. To obtain the man's engineering accomplishments after life and work of Parsons, I would like to quote what the 1911 until his death in 1931, I had to go on line to get this additional and fascinating information. There are a number of articles, books and other written material available about this great man and I have used a few of them for this blog.

Before going into the life and work of Parsons, I would like to quote what the1911 until his death in 1931, I had to go on line to get this additional and fascinating information.  There are a number of articles, books and other written material available about this great man and I have used a few of them for this blog. Cambridge University Press Cambridge University Press in 2014 had to say about him and I quote:

“The Evolution of the Parsons Steam Turbine: Responsible for the generation of most of the world's electricity, and with applications to sea and land transport, the steam turbine may be regarded as a pivotal invention in the creation of a technologically advanced modern society. Charles Parsons (1854 - 1931) built the first practical steam turbine in 1884, and he remained at the forefront of its development for nearly fifty years, as he saw his invention become first the prime means by which thermal energy could be turned into electricity, and then the power behind pioneering cruise liners and war ships. Alexander Richardson (1864 - 1928), an engineer and politician, had access to the inventor's papers when writing this account of the turbine's history. Published in 1911, and featuring more than 170 (173) illustrative plates, it provides a valuable insight into the development of a technology that revolutionized power generation, marine transport and naval warfare.”

This book is broken down into three general parts: (1) an account of research, theory, mechanical 

details of land and marine steam turbines, screw propellers, electric generators and speed reducing gears, (2) a record of progress in the application of steam turbines in propelling ships, driving electrical machines as well as other equipment and utilizing exhaust steam from reciprocating steam engines and (3) description of the manufacture of turbines, and of the Parsons Heaton original work shop and the other later Marine shop at Wallsend-onTyne (Turbilnia Works) near Newcastle.

Sir Charles Parsons was the son of an Irish Earl father, a famous astronomer, but was born in London.  He was tutored at his father's direction. He went to St. John's College at Cambridge and graduated in 1877. He was an excellent student and liked math and mechanical things of all kinds. After graduating, he was an apprentice for a two years and then joined a company where invented, designed and made a rotating piston steam engine with the pistons rotating at half the RPM as the  driver shaft.  This engine was only a novelty, but during WW I, the rotating pistons of a gasoline engine were attached to the propeller to drive several fighter planes.  He then became a junior partner in the a new company called  Messrs. Clarke, Chapman, Parsons and Company where Parsons was the chief electrical engineer, the company's works being located at Gateshead.

Parsons as part of this new company then after much thought and experimentation undertook the challenging task of inventing and making a practical steam turbine. Dr. Gustof de Laval of Sweden a year or so earlier had made a single stage impulse steam turbine that rotated at 30,000 RPM  having  a six inch diameter wheel. This turbine was not very practical and the stresses at this high speed were very high. At the time there were no steam tables to use and only a limited amount of knowledge about how steam actually expanded to push the piston down on the James Watt 100 year old machine.

Parsons originally thought of how he could imitate the piston movement in a rotating turbine by expanding the steam though a series of rotating blades to incrementally expand the steam stage by stage-- thus like a rotating piston. This is where the term reaction turbine came from by the steam expanding between the rotating blades.  He thought of the steam in terms of being a somewhat incompressible fluid at first, but was not completely right in all of his early thinking.  He neglected and ignored the aerodynamic movement of the steam over the blades at a rather high velocities. Saturated steam used at the time did produce drops of water as it expanded at a low velocity, but was a gas with a small mixture of water.

First Parsons steam turbine design

The first Parsons steam turbine looked more like a tinker toy than a turbine. The electric generator it drove stuck way up above the turbine to over shadowed it. The little turbine looked like a horizontally split flanged pipe 8 or 9 inch diameter about 2 1//2 feet long having end caps with holes in them for the shaft to stick out. There was a one inch ID pipe located on one side at the middle for the steam to enter and another 3 inch ID pipe on the other side at the middle for a the steam to exit to the atmosphere. The case had pedestal supports at each end. The rotor shaft of the bearings was only 1/2 an inch in diameter being enlarged to about 1 inch at the end caps. The journal bearing were 2 ½ inches long and were of a special flexible design to guard against rotor whip and were lubricated by a vertical 2-inch diameter pipe about 3 feet high. The rotor was about 3 and ½ inches in diameter and had flat blades about 5/16 of an inch long mounted in groves.

There was an inner casing around the rotor with a space between it and the outer casing for the 

stator blades and space on the outside for steam to flow. Located on the inside of the inner casing were 

secured 5/16 inch long stator blades. There were 14 stages of blading on each side of the center at a 45 degree angle having opposite directions on each side. In the drawings and photographs of the first unit, it appears that all the blades were about the same length, but the book says they increased in length downstream. However, this might have been the case later on when experiments showed this was necessary. If of the same length, then the exit velocity flow of the first turbine would have been quite high. The steam entered the casing and split with half flowing to the right and half to the left. After passing through the blading the steam reversed directions 180 degrees to flow back to the casing center where it was exhausted to the atmosphere. No thrust bearing was needed because of the balance in pressure with the right and left flow on the steam.

The governor was not very effective on this first unit and consisted of a fan and bellows operating one arm and a second arm from the electric generator working a throttle valves. Later on a new governing system was developed. The electric generator served as a brake to measure the output of the turbine.

The blades were made of pure copper of rather thick sheet metal. The blades had sharp rectangular edges without any regard for aerodynamics and acted like little paddles for the the steam to rotate the shaft by pushing against them to form small annular pistons according to how Parsons thought at the time. It took him several years to rethink the flow of the steam and realize the reaction that took place. The steam flowed mostly in parallel with the axis of the rotor and thus he called it a “parallel- flow” turbine.  We now call it an “axial flow” turbine.

In his next article, the author writes about the first little toy turbine and how Parsons formed his own company and went on to design the inward flowing steam turbine.

Ivan G. Rice was past chairman of the South Texas Section of ASME (1974 - 75), past chairman of the ASME Gas Turbine Division (now IGTI) (1975 - 76). A Life Fellow Member of ASME and Life Member of NSPE/TSPE, he has authored many articles and ASME papers on gas turbines, inter-cooling, reheat, HRSGs, steam cooling and steam injection.