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Generalized study on turbines and their most common types

Generalized study on turbines and their most common types -...

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Generalized study on turbines and their most common types Turbomachinery design is perhaps the most practical and most active application of the principles of fluid mechanics. There are billions of pumps and turbines in use in the world, and thousands of companies are seeking improvements. Turbines extract energy from flowing fluids and are of two types: impulse turbines, which convert the momentum of a high-speed stream, and reaction turbines, where the pressure drop occurs within the blade passages in an internal flow. The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and impart rotational energy to the rotor. Early turbine examples are windmills and water wheels The first turbines to be used were the steam turbines but now on the basis of the fluid from which energy is extracted there are three major types of turbines: Steam turbines Water turbines Wind turbines 1. STEAM TURBINE A steam turbine translates relatively high amount of the heat energy possessed in the steam to the mechanical rotary motion of a shaft which can be later converted into electrical energy.
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CONSTRUCTION OF A SINGLE-STAGE TURBINE The stea m chest and the casing contain the steam furnished to the turbine, being connected to the higher-pressure steam sup-ply line and the lower-pressure steam exhaust line, respectively. The steam chest, which is connected to the casing, houses the governor valve and the over-speed trip valve . The casing contains the rotor and the nozzles through which the steam is expanded and directed against the rotating buckets. The rotor consists of the shaft and disk assemblies with buckets. The shaft extends beyond the casing and through the bearing cases . One end of the shaft is used for coupling to the driven pump . The other end serves the speed governor and the over-speed trip systems. The bearing cases support the rotor and the assembled casing and steam chest. GENERAL WORKING OF STEAM TURBINES In the steam engines, the static pressure energy of the steam is utilized to obtain mechanical motion. It consists of a number of nozzles and a series of curved blades fixed on the circumference of a wheel called rotor (IMPULSE STEAM TURBINE). High pressure steam is passed through a nozzle — a converging passage, where it expands to a low pressure. Due to this fall in pressure of the steam, a certain amount of the heat energy is converted into kinetic energy and it flows out of the nozzle with a greater velocity. Then the rapid moving steam enters the moving part of the turbine which consists of the curved blades fitted on the rotor as shown in the figure.
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