Flywheel

The wheel on the end of the crankshaft that gives the crankshaft momentum to carry the pistons through the compression stroke.

A flywheel has two main functions:

1. Moderating speed fluctuations in an engine through its inertia. Any sudden increase due to fuelling changes or load on the system will be evened out.


2. Energy storage medium, as an alternative to the chemical battery.

The angular velocity is given by:

where

ω = angular velocity [rad s^-1]

N_rpm = rotational speed of the flywheel [revolutions per minute]

The angular acceleration is calculated as

where

α = angular acceleration in [rad s^-2]

ω_1,2 = angular velocity at time 1 and 2 [rad s^-1]

t = time between 1 and 2 [s]

The energy stored by the flywheel is

where

E = energy stored [J]

I = moment of inertia of the flywheel [kgm²]

ω = angular velocity of the flywheel [rad s^-1]

If the flywheel is attached to an engine then the energy from the engine per revolution is given as

where

E_engine = energy from engine per revolution [J]

P = engine power [W]

N_rpm = engine rotational speed [revolutions per minute]

See also: Engine Excitation Mechanisms, Internal Combustion Engine, Piston.