Science  People  Locations  Timeline
Index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Home > Flywheel


A flywheel is a heavy rotating disk used as a repository for angular momentum. Flywheels resist changes in their rotation speed, which helps steady the rotation of the shaft when an uneven 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-based pump). Flywheels can also be used by small motors to store up energy over a long period of time and then release it over a shorter period of time, temporarily magnifying its power output for that brief period. Recently, flywheels have become the subject of extensive research as power storage devices; see flywheel energy storage.

The kinetic energy stored in a rotating flywheel is

where I is the moment of inertia of the mass about the center of rotation and ω is the angular velocity in radian units. A flywheel is more effective when its inertia is larger, as when its mass is located farther from the center of rotation either due to a more massive rim or due to a larger diameter.

The flywheel has been used since ancient times, the most common traditional example being the potter's wheel. In the Industrial Revolution, James Watt contributed to development of the flywheel in the steam engineA steam engine is a heat engine that makes use of the potential energy that exists as pressure in steam, converting it to mechanical work. Steam engines were used in pumps, locomotive trains and steam ships, and were essential to the Industrial Revolution.

See also: gyroscopeA gyroscope is a device which demonstrates the principle of conservation of angular momentum, in physics. The essence of the device is a spinning wheel on an axle. The device, once spinning, tends to resist changes to its orientation. The gyroscope was in, momentum wheelA momentum wheel is a type of flywheel used primarily by spacecraft to change their angular momentum without using fuel for rockets or other reaction devices. They increase the pointing precision and reliability of a spacecraft, and may also reduce the ma, regenerative brakingRegenerative braking is any technology that allows a vehicle to recapture and store part of the kinetic energy that would ordinarily be lost when braking. A simpler technology that can only convert the energy to heat but which uses similar principles is k

Engine technology

Read more »

Non User