Que Grand Tu As et souple le gousier!: Systems of bulk power engineering. Part 2
"Que Grand Tu As et souple le gousier!"
François Rabelais. Gargantua (La vie très horrifique du grand Gargantua, père de Pantagruel, fils de Grandgousier).
Hydropower engineering. A macroscopic power engineering of water flows (classic hydropower engineering) is based on the use of energy of streams of water. In theoretical and practical researches of component of hydropower engineering applied science hydromechanics (mechanics of liquid) is engaged. It is the part of mechanics, which studies an equilibrium and motion of liquids, an interaction between them and the bodies submerged in liquids. The basic tasks of hydromechanics are:
determination of forces that operate on a solid, which moves in a liquid;
determination of parameters of liquid near the surface of solids;
research of motion of water in seas and oceans;
research of motion of liquid within the channels of a different form for determination of optimum form of channels.
Hydromechanics includes hydrodynamics and hydrostatics.
Hydrodynamics is also the part of hydro-aerodynamics, which studies motion of liquids that are not compressed and their interaction with solids.
The main physical properties of liquid that lie in a basis of theory of models are a continuity - distributing of phases of parameters in spacious, which characterize a liquid, and fluidity - weak counteraction of liquids to even small forces producing the relative sliding of particles of liquid. In the same time greater part of liquids shows considerable resistance to the compression and they almost do not change the volume under action of strange forces of pressure, normal to the surface that covers the given volume. In the theory of hydrodynamics for description of motion of uncompressed liquids that are characterized by fluidity and viscidity (parameter, that describes internal friction in liquids) the equations of continuity and Navie-Stoks equations are used, which result from the laws of conservation of mass and amount of motion with the relation to the elementary volume of liquid.
The methods of hydrodynamics allow calculating the velocity, pressure and other parameters of liquid in any point of space in a liquid at every instant. It enables to calculate the forces of pressure and friction that operate on a solid moving in a liquid.
The theory of filtration, theory of wave flow of liquid, theory of vortexes and theory of cavitations are component parts of hydrodynamics.
The theory of equilibrium of bodies in a liquid is studied by a hydrostatics.
A motion of electrolytes in the presence of the magnetic field is studied by magnetic hydrodynamics.
The methods of hydrodynamics are used for the decision of tasks of hydraulics, hydrology, hydraulic engineering, for calculation of hydro-turbines, pumps and pipelines.
In the hydroelectric power stations a potential energy of water grows into kinetic energy of streams of water and in kinetic energy of macroscopic elements (hydro-turbines), and electro-generators related to them, which at the rotation of electric windings in the magnetic field produce electric current.
Sun thermal power engineering. Sun energy can be regenerated in other forms of energy, more adjusted for the use by means of the well known technologies. The most applied technologies are thermal and photonic.
Sun thermal technologies allow converting sun energy at first into a heat that can be used directly for heating of water (for communal and commercial necessities) or grown into mechanical and electric energy by means of the proper equipment in thermal sun power-stations.
Thermal sun power-stations conclude a plenty of reflectors that are rotated after the Sun, sunlight is focused on a central receiver, which captures sun energy. A liquid circulated in a receiver carries a heat as steam and moves a steam-turbine for production of electric power.
The sun radiates electromagnetic waves that lie mainly in the range of 0,28…3,0 µm. Atmosphere of Earth transmits radiation in the ranges of 0,29…24 µm, 8 mm…20m. A sun spectrum consists of the following parts: ultraviolet (UV) waves with lengths of 0,28….0,38 µm (approximately 2 % of sun spectrum), visible waves in a range of 0,38…0,78 µm (about 49 % of spectrum), infra-red (IR) waves with lengths of 0,78…3,0 µm (approximately 49 % of sun spectrum).
Sun constant – an amount of energy of the Sun falling during 1 s on a area of
The sun radiates approximately 1,1x1020 kW·h of energy in a second. The external layers of atmosphere intercept approximately one millionth part of energy radiated by the Sun or 1,5 x 1018 kWxh annually.
Wind power engineering. Macroscopic wind power engineering is based on the use of energy of streams of moving air (wind). In the wind power plants kinetic energy of air flows grows into kinetic energy of wind-turbine, related to electro-generators. Kinetic energy of rotors is then transformed into electric current by means of the motion of wiring in the magnetic field.
Atmospheric air is never found in the state of rest. Energy of the sun, energy of celestial bodies, underground anomalies and natural atmospheric phenomena, cause to moving of considerable masses of air that are accompanied by transfer of large energies. The great part of energy of wind appears due to the uneven heating of terrene by the rays of the Sun. Near 1.2 % of sun energy grows into energy of wind. This quantity by 50…100 times exceeds the amount of energy regenerated into biomass by all plants of Earth.
The use of energy of wind is explained by the useful effect of mobile air. Mobile air has kinetic energy that is calculated as a product of mass of air on the square of his velocity. Specific weight of air is approximately equal to 10-3 kgxsm-3.
Equilibrium and motion of gaseous environments, interaction of gases and other submerged bodies are studied by aeromechanics - mechanics of gas. This applied science explores the behaviour of very complicated systems. The basic tasks of aeromechanics are the following:
determination of forces that act on a solid, which moves in gas;
determination of parameters of gas near the surface of solids;
research of motion of air in an atmosphere;
research of motion of gas within the channels of a different form.
Aeromechanics includes aerodynamics and aerostatics.
By means of the laws and equations of aerodynamics the values of aerodynamic forces and moments that operate on a body and also on separate his parts are calculated.
The development of aerodynamics is based on accumulation of the facts, got during the aerodynamic measuring of speed, pressure, density and temperature of moving air. The results of measuring are used for determination of carrying capacity, force of resistance and heating of surface of body, submerged in air.
Strength of wind is the measure of mechanical action of air on a body. Strength of wind is fully set, if the value, direction and point of appending are known. From the 2nd law of
In aerostatics the equilibrium of gas and his action on the submerged bodies are studied. At the compression of gas forces of resiliency appear in him that counterbalance the external forces. The macroscopic body placed in air is bombarded from all sides by the molecules of air.
To be continued…
By Vasil Sidorov on October 26,
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