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Betz's Limit
In aerodynamics, Betz's law indicates the maximum power that can be extracted from the wind, independent of the design of a wind turbine in open flow. It was published in 1919 by the German physicist Albert Betz.Betz, A. (1966) ''Introduction to the Theory of Flow Machines''. (D. G. Randall, Trans.) Oxford: Pergamon Press. The law is derived from the principles of conservation of mass and momentum of the air stream flowing through an idealized "actuator disk" that extracts energy from the wind stream. According to Betz's law, no wind turbine of any mechanism can capture more than 16/27 (59.3%) of the kinetic energy in wind. The factor 16/27 (0.593) is known as Betz's coefficient. Practical utility-scale wind turbines achieve at peak 75–80% of the Betz limit. The Betz limit is based on an open-disk actuator. If a diffuser is used to collect additional wind flow and direct it through the turbine, more energy can be extracted, but the limit still applies to the cross-section of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ratio
In mathematics, a ratio () shows how many times one number contains another. For example, if there are eight oranges and six lemons in a bowl of fruit, then the ratio of oranges to lemons is eight to six (that is, 8:6, which is equivalent to the ratio 4:3). Similarly, the ratio of lemons to oranges is 6:8 (or 3:4) and the ratio of oranges to the total amount of fruit is 8:14 (or 4:7). The numbers in a ratio may be quantities of any kind, such as counts of people or objects, or such as measurements of lengths, weights, time, etc. In most contexts, both numbers are restricted to be Positive integer, positive. A ratio may be specified either by giving both constituting numbers, written as "''a'' to ''b''" or "''a'':''b''", or by giving just the value of their quotient Equal quotients correspond to equal ratios. A statement expressing the equality of two ratios is called a ''proportion''. Consequently, a ratio may be considered as an ordered pair of numbers, a Fraction (mathematic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind Power
Wind power is the use of wind energy to generate useful work. Historically, wind power was used by sails, windmills and windpumps, but today it is mostly used to generate electricity. This article deals only with wind power for electricity generation. Today, wind power is generated almost completely using wind turbines, generally grouped into wind farms and connected to the electrical grid. In 2024, wind supplied over 2,494 TWh of electricity, which was 8.1% of world electricity. With about 100 Gigawatt, GW added during 2021, mostly Wind power in China, in China and the Wind power in the United States, United States, global installed wind power capacity exceeded 800 GW. 30 countries generated more than a tenth of their electricity from wind power in 2024 and wind generation has nearly tripled since 2015. To help meet the Paris Agreement goals to Climate change mitigation, limit climate change, analysts say it should expand much faster – by over 1% of electricity generation p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computational Fluid Dynamics
Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid dynamics, fluid flows. Computers are used to perform the calculations required to simulate the free-stream flow of the fluid, and the interaction of the fluid (liquids and gases) with surfaces defined by Boundary value problem#Boundary value conditions, boundary conditions. With high-speed supercomputers, better solutions can be achieved, and are often required to solve the largest and most complex problems. Ongoing research yields software that improves the accuracy and speed of complex simulation scenarios such as transonic or turbulence, turbulent flows. Initial validation of such software is typically performed using experimental apparatus such as wind tunnels. In addition, previously performed Closed-form solution, analytical or Empirical research, empirical analysis of a particular problem can be used for compa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gustav Kirchhoff
Gustav Robert Kirchhoff (; 12 March 1824 – 17 October 1887) was a German chemist, mathematician, physicist, and spectroscopist who contributed to the fundamental understanding of electrical circuits, spectroscopy and the emission of black-body radiation by heated objects. He also coined the term ''black body'' in 1860. Several different sets of concepts are named "Kirchhoff's laws" after him, which include Kirchhoff's circuit laws, Kirchhoff's law of thermal radiation, and Kirchhoff's law of thermochemistry. The Bunsen–Kirchhoff Award for spectroscopy is named after Kirchhoff and his colleague, Robert Bunsen. Life and work Gustav Kirchhoff was born on 12 March 1824 in Königsberg, Prussia, the son of Friedrich Kirchhoff, a lawyer, and Johanna Henriette Wittke. His family were Lutheranism, Lutherans in the Evangelical Church of Prussia. He graduated from the Albertus University of Königsberg in 1847 where he attended the mathematico-physical seminar directed by Carl Gusta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexander Gorlov
Alexander M. Gorlov (March 23, 1931 – June 10, 2016) was a Russian mechanical engineer who was Professor Emeritus and Director of Hydro-Pneumatic Power Laboratory at Northeastern University in Boston, Massachusetts. Early life Alexander M. Gorlov was born into the family of a prosperous lawyer. His father was arrested and died in prison during Joseph Stalin's purges. His mother also spent a number of years in concentration camps in Russia, which forced young Alexander Gorlov to spend some of his childhood years in the orphanage in a remote Russian Urals area. Gorlov received his Doctorate in engineering and had a successful scientific career in Moscow for a number of years during the relatively liberal period of the so-called Khrushchev Thaw. He was granted the Gold and two Bronze Medals for Achievements of the USSR National Economy. In 1975 because of his friendship with Alexander Solzhenitsyn, the Nobel Prize winner and outspoken critic of the communist system, Gorlov was fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexander Nikolaevich Gorban
Alexander Nikolaevich Gorban () is a scientist of Russian origin, working in the United Kingdom. He is a professor at the University of Leicester, and director of its Mathematical Modeling Centre. Gorban has contributed to many areas of fundamental and applied science, including statistical physics, non-equilibrium thermodynamics, machine learning and mathematical biology. Gorban is the author of about 20 books and 300 scientific publications. He has founded several scientific schools in the areas of physical and chemical kinetics, dynamical systems theory and artificial neural networks, and is ranked as one of the 1000 most cited researchers of Russian origin.According to http://www.scientific.ru/, 2012 In 2020, Gorban presented a keynote talk at the IEEE World Congress on Computational Intelligence. Gorban has supervised 6 habilitations and more than 30 PhD theses. Biography Gorban was born in Omsk, on 19 April 1952. His father Nikolai Vasilievich Gorban was a historian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hermann Glauert
Hermann Glauert, FRS (4 October 1892 – 6 August 1934) was a British aerodynamicist and Principal Scientific Officer of the Royal Aircraft Establishment, Farnborough until his death in 1934. Early life and education Glauert was born in Sheffield, Yorkshire; his father Louis Glauert was a cutlery manufacturer. He attended King Edward VII School, Sheffield and Trinity College, Cambridge. Career Glauert wrote numerous reports and memoranda dealing with aerofoil and propeller theory. His book, ''The Elements of Aerofoil and Airscrew Theory'' was the single most important instrument for spreading airfoil and wing theory around the English speaking world. Glauert independently developed Prandtl-Glauert method from the then-existing aerodynamic theory and published his results in '' The Proceedings of the Royal Society'' in 1928. In the 1930s, he was the academic supervisor of aerodynamicist and educationalist Gwen Alston. Death Glauert died in 1934, aged 41, in an accid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind-powered Vehicle
Wind-powered vehicles derive their power from sails, kites or wind turbine, rotors and ride on wheels—which may be linked to a wind-powered rotor—or runners. Whether powered by sail, kite or rotor, these vehicles share a common trait: As the vehicle increases in speed, the advancing airfoil encounters an increasing apparent wind at an angle of attack that is increasingly smaller. At the same time, such vehicles are subject to relatively low forward resistance, compared with traditional sailing craft. As a result, such vehicles are often capable of speeds exceeding that of the wind. Rotor-powered examples have demonstrated ground speeds that exceed that of the wind, both directly ''into the wind'' and directly ''downwind'' by transferring power through a drive train between the rotor and the wheels. The wind-powered speed record is by a vehicle with a sail on it, ''Greenbird'', with a recorded top speed of . Other wind-powered conveyances include sailing vessels that travel on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blade Element Momentum Theory
Blade element momentum theory is a theory that combines both blade element theory and momentum theory. It is used to calculate the local forces on a propeller or wind-turbine blade. Blade element theory is combined with momentum theory to alleviate some of the difficulties in calculating the induced velocities at the rotor. This article emphasizes application of blade element theory to ground-based wind turbines, but the principles apply as well to propellers. Whereas the streamtube area is reduced by a propeller, it is expanded by a wind turbine. For either application, a highly simplified but useful approximation is the William Rankine, Rankine–Robert Edmund Froude, Froude "momentum" or "actuator disk" model (1865, 1889). This article explains the application of the "Betz's law, Betz limit" to the efficiency of a ground-based wind turbine. Froude's blade element theory (1878) is a mathematical process to determine the behavior of Propeller, propellers, later refined by Glauer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proof
Proof most often refers to: * Proof (truth), argument or sufficient evidence for the truth of a proposition * Alcohol proof, a measure of an alcoholic drink's strength Proof may also refer to: Mathematics and formal logic * Formal proof, a construct in proof theory * Mathematical proof, a convincing demonstration that some mathematical statement is necessarily true * Proof complexity, computational resources required to prove statements * Proof procedure, method for producing proofs in proof theory * Proof theory, a branch of mathematical logic that represents proofs as formal mathematical objects * Statistical proof, demonstration of degree of certainty for a hypothesis Law and philosophy * Evidence, information which tends to determine or demonstrate the truth of a proposition * Evidence (law), tested evidence or a legal proof * Legal burden of proof, duty to establish the truth of facts in a trial * Philosophic burden of proof, obligation on a party in a dispute to provi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power And Work
Power may refer to: Common meanings * Power (physics), meaning "rate of doing work" ** Engine power, the power put out by an engine ** Electric power, a type of energy * Power (social and political), the ability to influence people or events Mathematics, science and technology Computing * IBM POWER (software), an IBM operating system enhancement package * IBM POWER architecture, a RISC instruction set architecture * Power ISA, a RISC instruction set architecture derived from PowerPC * IBM Power microprocessors, made by IBM, which implement those RISC architectures * Power.org, a predecessor to the OpenPOWER Foundation Mathematics * Exponentiation, "''x'' to the power of ''y''" * Power function * Power of a point * Statistical power Physics * Magnification, the factor by which an optical system enlarges an image * Optical power, the degree to which a lens converges or diverges light Social sciences and politics * Economic power, encompassing several concepts that economists use, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
