Flywheel

For other uses, see Flywheel (disambiguation).

Video of a flywheel that keeps its rotation rate higher than in a rigid design, constructed based on drawings by Leonardo da Vinci

A flywheel is a rotating disc used as a storage device for kinetic energy. Leonardo di ser Piero da Vinci ( April 15 1452 – May 2 1519 was an Italian Polymath, having been a scientist Mathematician, Engineer The kinetic energy of an object is the extra Energy which it possesses due to its motion Flywheels resist changes in their rotational speed, which helps steady the rotation of the shaft when a fluctuating torque is exerted on it by its power source such as a piston-based (reciprocating) engine, or when the load placed on it is intermittent (such as a piston pump). Rotational speed (sometimes called speed of revolution) indicates for example how fast a motor is running A torque (τ in Physics, also called a moment (of force is a pseudo- vector that measures the tendency of a force to rotate an object about A piston is a component of Reciprocating engines Pumps and Gas compressors It is located in a cylinder and is made gas-tight by Piston A reciprocating engine, also often known as a piston engine, is a Heat engine that uses one or more reciprocating Pistons to convert An engine is a mechanical device that produces some form of output from a given input For information on Wikipedia project-related discussions see WikipediaVillage pump. Flywheels can be used to produce very high power pulses as needed for some experiments, where drawing the power from the public network would produce unacceptable spikes. A small motor can accelerate the flywheel between the pulses. Recently, flywheels have become the subject of extensive research as power storage devices for uses in vehicles; see flywheel energy storage. Flywheel Energy Storage (FES works by accelerating a Rotor ( Flywheel) to a very high speed and maintaining the energy in the system as Rotational energy

1 Physics
- 1.1 High energy materials
2 Applications
3 History
4 See also
5 References
6 External links

Physics

Spoked flywheel

Energy is stored in the rotor as kinetic energy, or more specifically, rotational energy:

$E_k=\frac{1}{2}\cdot I\cdot \omega^2$

where

ω

is the angular velocity, and

I

is the moment of inertia of the mass about the center of rotation. The kinetic energy of an object is the extra Energy which it possesses due to its motion The rotational energy or angular kinetic energy is the Kinetic energy due to the rotation of an object and is part of its total kinetic energy. Do not confuse with Angular frequency The unit for angular velocity is rad/s This article is about the moment of inertia of a rotating object. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object

The moment of inertia for a solid-cylinder is $I_z = \frac{1}{2} mr^2$ ,
for a thin-walled cylinder is $I = m r^2 \,$ ,
and for a thick-walled cylinder is $I = \frac{1}{2} m({r_1}^2 + {r_2}^2)$ .

where m denotes mass, and r denotes a radius. More information can be found at list of moments of inertia

The amount of energy that can safely be stored in the rotor depends on the point at which the rotor will warp or shatter. The following is a list of moments of inertia. Mass moments of inertia have units of dimension mass × length2 The hoop stress on the rotor is a major consideration in the design of a flywheel energy storage system. Hoop stress is mechanical stress defined for rotationally-symmetric objects being the result of forces acting circumferentially (perpendicular both to the axis and to the radius

$\sigma_t = \rho r^2 \omega^2 \$

where

σ t

is the tensile stress on the rim of the cylinder

ρ

is the density of the cylinder

r

is the radius of the cylinder, and

ω

is the angular velocity of the cylinder. Do not confuse with Angular frequency The unit for angular velocity is rad/s

High energy materials

Flywheel from stationary engine. A stationary engine is an engine whose framework does not move Note the castellated rim which was used to rotate the engine to the correct starting position by means of a lever. A castellated nut (also called a castle nut or a slotted nut) is a nut with slots (notches cut into one end

For a given flywheel design, it can be derived from the equations above that the kinetic energy is proportional to the ratio of the hoop stress to the material density.

$E_k \varpropto \frac{\sigma_t}{\rho}$

This parameter could be called the specific tensile strength. The flywheel material with the highest specific tensile strength will yield the highest energy storage. This is one reason why carbon fiber is a material of interest.

Applications

A Landini tractor with massive flywheel

Main article: flywheel energy storage

In application of flywheels in vehicles, the phenomenon of precession has to be considered. Landini SpA headquartered in Fabbrico, Italy, was founded by Giovanni Landini in 1884 to produce agricultural equipment Flywheel Energy Storage (FES works by accelerating a Rotor ( Flywheel) to a very high speed and maintaining the energy in the system as Rotational energy Precession refers to a change in the direction of the axis of a rotating object A rotating flywheel responds to any momentum that tends to change the direction of its axis of rotation by a resulting precession rotation. A vehicle with a vertical-axis flywheel would experience a lateral momentum when passing the top of a hill or the bottom of a valley (roll momentum in response to a pitch change). Two counter-rotating flywheels may be needed to eliminate this effect.

1898 illustration of a White and Middleton stationary engine; note the large twin flywheels. The White and Middleton Gas Engine Company was a manufacturer of Internal combustion engines in the late 19th and early 20th centuries headquartered in Baltimore,

The flywheel has been used since ancient times, the most common traditional example being the potter's wheel. In Pottery, a potter's wheel is a machine used in the shaping of round ceramic wares In the Industrial Revolution, James Watt contributed to the development of the flywheel in the steam engine, and his contemporary James Pickard used a flywheel combined with a crank to transform reciprocating into rotary motion. The Industrial Revolution was a period in the late 18th and early 19th centuries when major changes in agriculture manufacturing and transportation had a profound effect on the James Watt ( 19 January 1736 &ndash 25 August 1819 Boulton proved to be an excellent businessman and both men eventually made fortunes A steam engine is a Heat engine that performs Mechanical work using Steam as its Working fluid. James Pickard was an English inventor He modified the Newcomen engine in a manner that it could deliver a rotary motion A crank is an arm at right angles to a shaft (an Axle or spindle by which motion is imparted to or received from the shaft it is also used to change circular into Reciprocating

In a more modern application, a momentum wheel is a type of flywheel useful in satellite pointing operations, in which the flywheels are used to point the satellite's instruments in the correct directions without the use of thruster rockets.

Flywheels are used in punching machines and riveting machines where it stores energy from the motor and releases it during the main operation (punching and riveting). Metals Punching in metal fabrication is the process of using a machine to press a shape through a sheet of metal and into a die to create A rivet is a mechanical Fastener. Before it is installed it consists of a smooth cylindrical shaft with a head on one end

History

The principle of the flywheel is already found in the Neolithic spindle and the potter's wheel. A spindle (sometimes called a drop spindle) is a Wooden spike weighted at one end with a circular Whorl; it may have an optional hook at either end of the In Pottery, a potter's wheel is a machine used in the shaping of round ceramic wares ^[1]

The flywheel as a general mechanical device for equalizing the speed of rotation is first described in the Kitab al-Filaha of the Andalusian engineer Ibn Bassal (fl. Al-Andalus (الأندلس was the Arabic name given to those parts of the Iberian Peninsula governed by Muslims or 1038-1075), who applies the device in a chain pump (saqiya) and noria. The chain pump is a type of water Pump where an endless chain has positioned on it a series of circular discs A noria (ناعورة nā‘ūra, from ܢܥܘܪܐ nā‘urā) is a machine for lifting water into an Aqueduct using energy derived from the water's ^[2]

According to the American medievalist Lynn Townsend White, Jr., such a flywheel is also recorded in the De diversibus artibus (On various arts) of the German artisan Theophilus Presbyter (ca. Lynn Townsend White Jr ( April 29 1907 – March 30 1987) was a professor of medieval History at Princeton, Theophilus Presbyter (approx 1070 - 1125) was a Benedictine monk and author of a Latin text containing detailed descriptions of various medieval 1070-1125), who records applying the device in several of his machines. ^[1]^[3]

References

^ ^a ^b Lynn White, Jr. This is a list of energy topics which identifies articles and categories that relate to energy in general A gyroscope is a device for measuring or maintaining orientation, based on the principles of Angular momentum. An inductor is a passive electrical component designed to provide Inductance in a circuit A plug-in hybrid electric vehicle ( PHEV) is a Hybrid vehicle with batteries that can be recharged by connecting a plug to an Electric power See also Rechargeable electricity storage system A rechargeable battery, also known as a storage battery, is a group of two or more secondary A regenerative brake is a mechanism that reduces Vehicle speed by converting some of its Kinetic energy into another useful form of energy Electric double-layer capacitors, also known as supercapacitors, electrochemical double layer capacitors ( EDLCs) or ultracapacitors , “Theophilus Redivivus”, Technology and Culture, Vol. 5, No. 2. (Spring, 1964), Review, pp. 224-233 (233)
^ Ahmad Y Hassan, Flywheel Effect for a Saqiya. Ahmad Y Hassan أحمد يوسف الحسن(born 1925 is a chevalier of the Légion d'honneur and a historian of Arabic and Islamic science and technology
^ Lynn White, Jr. , “Medieval Engineering and the Sociology of Knowledge”, The Pacific Historical Review, Vol. 44, No. 1. (Feb. , 1975), pp. 1-21 (6)

External links

Flywheel highlight: Hypervideo showing construction and operation of four cylinder internal combustion engine (courtesy of Ford Motor Company)

Dictionary

-noun

a rotating mass used to maintain the speed of a machine within certain limits while the machine receives or releases energy at a varying rate

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