EVERYTHING ABOUT TURBINE
What is meant by a TURBINE?
A Turbine is a Mechanical and Rotary type device which extracts the energy from the flow of a fluid and then converts the energy from the flow into useful work. A turbine is a special Turbo Machine which consists of at least one moving part. The moving part is known as Rotor Assembly. The flowing fluid acts on the blades directly in a way such that they move and impart a type of rotational energy to the motor and its components. In olden days, Turbines are also named as Windmills and Waterwheels. The invention of Steam Engine is given to British Engineers, Sir Charles Parsons for inventing Reaction Turbine and Swedish Engineer Gustaf de Laval for inventing Impulse Turbine. In modern times, both the Reaction turbines and Impulse turbines are used just by varying the degree of reaction.
Theory of Operation-
Let us talk about casual waterfalls we see in our daily life. Any waterfall contains water falling down at high speeds. This speed of water is used. The speed of the water is nothing but Kinetic Energy. The water falls from a height. It is the Potential Energy. So clearly we can understand the Potential Energy is getting converted to Kinetic Energy and this Kinetic energy is converted to useful work. The fluid flowing can be both compressible and incompressible.
Impulse Turbines always changes its direction of flow of any fluid of high velocity. The resulting change spins the turbine and gives the diminished fluid flow with lowering Kinetic Energy. We can see no pressure changes of the fluid in the turbine. Before it reaches the turbine, the pressure of the fluid changes and velocity head gets accelerated with a nozzle. The working of Impulse Turbine is also used in both Pelton Wheels and De Laval Turbines. The principle of Impulse Turbine is completely defined by Newton’s Second Law.
Reaction Turbines are the other type of turbines used mostly in modern days. It develops torque by their reaction to the fluid. The characteristics of the fluid changes as it once gets entered into the turbine. Reaction Turbine needs a pressure casement to maintain the working fluid in the parts of the turbine. The casing sends the water directly for the extraction of energy. For compressible fluids, multiple stages are used to maintain and harness the expanding gas efficiency. The principle of Reaction Turbine is completely defined by Newton’s Third Law.
Steam Turbines would be used primarily for Marine applications and also for Land Based Electricity generation. There is a type of turbine known as Parsons type reaction turbine that works usually with twice the number of blade rows same as the De Laval type Impulse Turbine. This is for the same degree of Thermal Energy conversion. These qualities make the Parsons Turbine stand alone with much longer life and heavier. The overall efficiency of this turbine is exactly or greater than equivalent impulse turbine which is for the same thermal energy.
Wind turbines are very useful and many development and experimental programs are being conducted as air is the best source of renewable energy. These type of turbines use Air Foil to bring out the reaction lift from the moving part of the wind and then send it to the rotor. Wind turbines gather energy from the thrust or impulse by the wind, my placing it and deflecting it with a specified angle with which we can gain more energy. Turbines with multiple stages are also used but they are not mostly implemented as they are very complex in nature.
Velocity Triangles can be used to calculate the performance of the turbine as a whole. Mean Performances for the stages can be found out from Velocity Triangles by only using Euler’s Equation. Modern Turbine designs are really much more complex but give a very reliable output by calculating both Computational and Fluid Dynamics. These tools are used very effectively which further led us for the gradual improvements in Turbine from the last four decades. Specific Speed is an important factor to be considered for the development of design. The performance can be analyzed and can be increased too. Some fundamental formulas are used for the varying performance and desired output can be achieved.
Types of Turbines-
Steam Turbines are preferably used in the generation of electricity in all plants, mostly in Thermal Power Plants such as the plants that run on Coal, Fuel or Nuclear fuel. Turbinia is the first turbine that is powered by Steam. The turbo electric machinery was very popular just before the World War-II and during the war, which are mostly used by United States and United Kingdom shipyards.
Gas Turbines are often referred to as Turbine Engines. These type of Engines are usually equipped with inlet, a fan, a small nozzle, a compressor and a combustion chamber in addition for one or more turbines with these parts or more parts.
Transonic Turbine is used in the Gas Turbine Engines which remain subsonic for the whole expansion process. In this Transonic Turbine, the supply of the gas converts to the supersonic gas when exiting though downstream velocities are normally subsonic.
Contra Rotating Turbines are also known as Ljugstrom turbine. We know that the name of the turbine is the person who invented it in most cases. It is applicable in this case too. Fredrik Ljugstrom, a Swedish Engineer invented it in Stockholm with the co-operation of his bigger brother Birger Ljungstrom. It is a multistage radial turbine which offers great efficiency nearly four times that of the Parsons Turbine.
Stator less Turbine is also a multistage turbine that comprises of a set of inlet static guide vanes which helps in directing the gas flow to the rotating rotor blades. It re arrange the pressure and velocity energy levels of the flow that being encountered with the turbine. Stator less turbine does not consist of a stator as it is indicated directly in the name of the turbine.
Ceramic Turbine consists of very high pressure blades for the turbine and are made of Nickel based alloys. In the followed years after the invention, experimental ceramic blades have been constructed from the alloys and tested in gas turbines. It made the possibility of retrieving great and innovative ideas which changed the future.
Shrouded Turbine have shrouding at the top of the rotor blades, which has interlocks that helps to increase damping and gradually reduce the buffer flutter. This shrouding is almost very complemented, mentioning the names f long blades of low pressure. There is also Shroud less Turbine to eliminate he rotor shrouding.
Blade less Turbine only use the boundary layer effect on the blades as the same in a conventional type turbine.
Water Turbine has five types of turbines. They are as follows
Cross Flow Turbine
Wind Turbines are usually operated single and kept steady all the time and the energy extracted is directed to the use. They make no changes to it unless for any repair of rotor or stator.
Mercury Vapor Turbines always use Mercury as the working fluid. They don’t use any of the naturally available resources like water, gas or steam. These are used for improving the efficiency of the generating stations of the fossil fueled type. The toxic level of the mercury was immediately apparent.
Almost all the energy used on the earth is based on turbines calculation as of today. Other energy sources include nonrenewable or exhaust sources that come to end on usage in the future. Military jets, air planes, space shuttles, jet engines and all are maintained with mechanical work and there will be no deficiency of Mechanical Energy.