Early Steam Turbines

The oldest steam turbine known design dates are from the Greeks about 10 yrs A. D., and is known as Hero's Aeolipile . The name – derived from the Greek words "aeolos" and "pila" – translates to "the ball of Aeolus“ (Aeolus : Greek god of the wind). Here is an image,

It was driven by the thrust of two tangential outlet pipes and that’s the reason it was called Reaction Turbine.

In 1629 in Italy, Giovanni Branca proposed fixed steam jets impinging on rotating blades that’s the Impulse Turbine.

In 1837 in the United States, William Avery used Hero’s concept to build machines up to 5 ft in diameter, with peripheral speeds of 900 ft/s, to drive woodworking machinery. They were abandoned because of control difficulties and unreliability.

Gustav de Laval (an Swedish engineer) used a similar device to power a centrifuge, then in the 1890s turned to single-stage impulse turbines. These used a convergent-divergent nozzle to fully expand the steam and had rotor speeds of up to 30,000 rpm.

The success of the steam turbine began when Charles Parsons solved the problem of high velocities by applying pressure compounding to divide pressure drop between a large number of reaction stages along the axis of the turbine.

In 1886 in France, Professor Rateau invented pressure compounded the impulse turbine.

Charles Gordon Curtis addressed the steam velocity problem by velocity compounding, i.e. directing steam from a single row of nozzles onto several rows of moving impulse blades with intervening fixed guide blades.

In the United Kingdom, the most rapid development was marine. In 1897, Parsons raced through a fleet review by Queen Victoria in his launch, Turbinia. It was capable of 34 knots, and outpaced the fastest Royal Navy patrol boats. The implications were clear, and by 1905, turbine power was exclusively selected for British warships.

Turbinia was the first steam turbine powered steamship. Built as an experimental vessel in 1894, and easily the fastest ship in the world at that time. Propelled by three-stage Radial-flow direct-acting Parsons steam turbine. See below two image..

After 1910, development was rapid, aided by the acceptance of alternating current, which permitted efficient blade design in turbines direct coupled to generators operating at 3000 rpm.

By the 1920, efficiency was improved by condensers, super heating, and feed heating.

Super critical steam cycles with steam pressure and temperature conditions of 340 bars / 650°C and double reheat were introduced in the 1960. Materials difficulties caused reduction to 240 bars / 560°C.

In the last decade, combined cycles have become a major steam turbine application

Today those of us who work with steam turbines for a electricity are familiar with axial-flow turbines, where steam flows through a series of rotating and stationary blades in a direction along the shaft. Below is a cutaway of a small five stage turbine.

In above sketch, Steam enters at the left from an opening on the upper half of the casing, flows along the shaft axis (so the term axial-flow turbine), then the steam exits the turbine from a large opening at the right, on the upper half of the casing. This is the typical flow path on all modern steam turbines.

However, the Parsons Turbine that powered the ship Turbinia was a Radial-Flow turbine. In this turbine, the steam flow path was outward from the shaft to the casing.

To be clear, the steam in this turbine also travels along the turbine shaft (axial), but it is only making power while traveling outward (radially) toward the casing. Steam enters at the lower left in this picture.