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At entry to the turbine, the steam gains kinetic energy by passing through a nozzle (a fixed nozzle in an impulse type turbine or the fixed blades in a reaction type turbine). When the steam leaves the nozzle it is moving at high velocity towards the blades of the turbine rotor.
A steam turbine with the case opened Humming of a small pneumatic turbine used in a German 1940s-vintage safety lamp. A turbine (/ ˈ t ɜːr b aɪ n / or / ˈ t ɜːr b ɪ n /) (from the Greek τύρβη, tyrbē, or Latin turbo, meaning vortex) [1] [2] is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work.
Fig-3: Schematic Diagram of Pressure compounded Impulse Turbine. The pressure compounded Impulse turbine is also called a Rateau turbine, after its inventor. This is used to solve the problem of high blade velocity in the single-stage impulse turbine. It consists of alternate rings of nozzles and turbine blades.
Practical hydroelectric water turbines and steam turbines did not appear until the 1880s. Gas turbines appeared in the 1930s. The first impulse type turbine was created by Carl Gustaf de Laval in 1883. This was closely followed by the first practical reaction type turbine in 1884, built by Charles Parsons.
The degree of reaction contributes to the stage efficiency and thus used as a design parameter. Stages having 50% degree of reaction are used where the pressure drop is equally shared by the stator and the rotor for a turbine. Figure 4. Velocity triangle for Degree of Reaction = 1/2 in a turbine
The exit steam from one turbine is made to enter the nozzle of the succeeding turbine. Each of the simple impulse turbines would then be termed a "stage" of the turbine. Each stage comprises its ring of nozzle and blades. The steam from the boiler passes through the first nozzle ring, where its pressure drops and velocity increases. [2]
In 1882 he introduced his concept of an impulse steam turbine [2] and in 1887 built a small steam turbine to demonstrate that such devices could be constructed on that scale. In 1890, Laval developed a nozzle to increase the steam jet to supersonic speed, working from the kinetic energy of the steam, rather than its pressure.
The Ljungström turbine (Ljungströmturbinen) is a steam turbine. It is also known as the STAL turbine, from the company name STAL ( Swedish : Svenska Turbinfabriks Aktiebolaget Ljungström ). The technology has had numerous uses since its conception, from power plants to vehicles as large as the supertanker Seawise Giant .