Turbine
Turbine is the generic name given to most motor turbomachinery. These are fluid machines, through which a fluid passes continuously and this gives it its kinetic energy through an impeller with blades or blades.
A turbine is a rotating engine that converts the kinetic energy of a stream of water, steam, or gas into mechanical energy. The basic element of the turbine is the wheel or rotor, which has blades, propellers, blades or hubs placed around its circumference, in such a way that the moving fluid produces a tangential force that drives the wheel and makes it rotate. This mechanical energy is transferred through a shaft to provide the motion of a machine, a compressor, an electrical generator, or a propeller.
Turbines consist of 1 or 2 bladed wheels, called rotor and stator, the first being the one that, driven by the fluid, drags the axis in which the rotation movement is obtained.
So far, the turbine is one of the most efficient engines that exist (around 50%) compared to internal combustion engines and even some electric ones. Already in the 1920s, some inventors, including one named Thyssen, patented an internal combustion turbine to which they attributed a thermodynamic efficiency of 31%.
The term turbine is usually also applied, because it is the main component, to the set of several turbines connected to a generator to obtain electrical energy. The term was coined in 1822 by French mining engineer Claude Burdin from the Greek τύρβη, tyrbē, meaning "vortex" or "spinning,", in a memorandum, "Des turbines hydrauliques ou machines rotatoires à grande vitesse," which he presented at the Académie royale des sciences in Paris. Benoit Fourneyron, a former student of Claude Burdin, built the first practical water turbine.
Classification
Turbines can be classified into two main subgroups: hydraulic and thermal.
Hydraulic turbines
They are those whose working fluid does not undergo a considerable change in density through its passage through the impeller or through the stator; These are generally water turbines, which are the most common, but windmills or wind turbines can still be classified as hydraulic turbines.
Within this genre, we usually talk about:
- Turbines of action
- They are those in which the fluid does not suffer any change of pressure through its passage through the surround. The pressure that the fluid has at the entrance to the turbine is reduced to atmospheric pressure in the guideline crown, keeping constant throughout the round. Its main characteristic is that they lack aspiration pipe. The main turbine of action is Turbine Pelton, whose flow is tangential. They are characterized by a specific number of low revolutions (ns backwards=30). The distributor in these turbines is called injector.
- Reaction turbines
- They are those in which the fluid suffers a considerable change of pressure in its passage through the surround. The fluid enters the roundabout with a pressure superior to the atmospheric and at the exit of it presents a depression. They are characterized by a suction pipe, which unites the exit of the rodete with the fluid discharge zone. These turbines can be divided according to the configuration of the links. Thus, there are the turbines of fixed alabs (Francis-/2005Radial axial, not diagonal; Helice-giveFlujo axial) and turbines with orientable links (Deriaz-gflujo diagonal; Kaplan-glujo axial). The use of orientable links allows greater hydraulic performances.
The range of application (an approximation) of the turbines, from lowest to highest head is: kaplan-francis-pelton
The specific number of revolutions is a common number for all geometrically similar turbines/pumps (from lowest to highest it is: pelton-francis-kaplan). The greater the specific number of revolutions, the greater the risk of turbine cavitation, that is, a Kaplan Turbine is more likely to have cavitation than a Francis or Pelton Turbine.
Thermal turbines
They are those whose working fluid undergoes a considerable change in density through its passage through the machine.
These are often classified into two distinct subsets due to their fundamental design differences:
- Steam turbines
- Your workflow may undergo a phase change during your passage through the roundabout; this is the case of mercury turbines, which were popular at some point, and that of water vapor turbines, which are the most common.
- Gas turbines
- In this type of turbines a phase change of the fluid is not expected during its passage through the roundup.
Also when talking about thermal turbines, we usually talk about the following subgroups:
- Turbines to action
- In this type of turbines the enthalpic leap occurs only in the stator, giving itself the transfer of energy only by action of the change of fluid speed.
- Turbines in reaction
- The enthalpic jump is made both in the surround and in the stator, or possibly only in the rotor.
Equally common is to classify turbines by the pressure existing in them in relation to other turbines arranged in the same group:
- High-pressure turbines
- They are the smallest of all stages and are the first ones where the work fluid enters the turbine.
- Medium-pressure turbines
- Low-pressure turbines
- They are the last of all stages, they are the longest and can no longer be modeled by the eulerian description of turbomáquinas etc.
Wind Turbines
A wind turbine is a mechanism that transforms wind energy into another form of useful energy such as mechanical or electrical.
The kinetic energy of the wind is transformed into mechanical energy by means of the rotation of an axis. This mechanical energy can be used to grind, as in the old windmills, or to pump water, as in the case of the multi-blade mill. Mechanical energy can be transformed into electricity by means of an electrical generator (an alternator or a dynamo). The electrical energy generated can be stored in batteries or used directly.
Underwater turbine
An underwater turbine is a mechanical device that converts the energy of underwater currents into electrical energy. It consists of taking advantage of the kinetic energy of underwater currents, fixing turbines mounted on prefabricated towers to the underwater bottom so that they can rotate in search of underwater currents. Since the speed of these currents varies throughout a year, they must be located in the most favorable places where the speed of the currents varies between 3 km/h and 10 km/h to implant turbine power plants preferably at depths as deep as possible. shallow as possible and that do not harm any underwater ecosystem. The turbines would have a protection mesh that would prevent the absorption of aquatic animals.
Uses
A large proportion of the world's electrical power is generated by turbogenerators.
Turbines are used in gas turbine engines on land, sea, and in the air.
Turbochargers are used in piston engines.
Gas turbines have very high power densities (ie power/mass or power/volume ratio) because they operate at very high speeds. The space shuttle's main engine used turbopumps (machines consisting of a pump driven by a turbine engine) to power propellants (liquid oxygen and liquid hydrogen) in the engine's combustion chamber. The liquid hydrogen turbopump is slightly larger than a car engine (weighing approximately 700 lbs.) and the turbine produces almost 70,000 hp (52.2 MW).
Turboexpanders are used for cooling in industrial processes.
For more information
- Layton, Edwin T. "From Rule of Thumb to Scientific Engineering: James B. Francis and the Invention of the Francis Turbine," NLA Monograph Series. Stony Brook, NY: Research Foundation of the State University of New York, 1992.