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A 250 kW industrial steam turbine from 1910 (right) directly linked to a generator (left). The first device that may be classified as a reaction steam turbine was little more than a toy, the classic Aeolipile, described in the 1st century by Hero of Alexandria in Roman Egypt.
As explained earlier a reaction turbine is one in which there is pressure and velocity loss in the moving blades. The moving blades have a converging steam nozzle. Hence when the steam passes over the fixed blades, it expands with decrease in steam pressure and increase in kinetic energy.
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
An illustration of Hero's aeolipile. An aeolipile, aeolipyle, or eolipile, from the Greek "Αἰόλου πύλη," lit. ' Aeolus gate ', also known as a Hero's (or Heron's) engine, is a simple, bladeless radial steam turbine which spins when the central water container is heated.
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.
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]
The uniflow engine used poppet valves and half cylinders which allowed steam to pass into the engine was then used to create a high pressure environment that was key to the function of the uniflow engine. It was used in ships, steam locomotives and steam wagons but was displaced by steam turbines and later marine diesel engines. [50] [52] [53] [17]
The steam passing through the last stage of turbine has a high velocity and a large moisture content. The liquid particles have lesser velocity than that of vapor particles; hence, the liquid particles obstruct the flow of vapor particles in the last stage of the turbine, and therefore, a part of kinetic energy of the steam is lost.