The wheel on the end of the crankshaft that gives the crankshaft momentum to carry the pistons through the compression stroke.
Normally constructed from a heavy steel or iron disc.
A flywheel has two main functions:
- 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.
- Energy storage medium, as an alternative to the chemical battery.
The angular acceleration of a flywheel is:
α = angular acceleration in [rad s-2]
ω1,2 = angular velocity at time 1 and 2 [rad s-1]
t = time between 1 and 2 [s]
The angular velocity of a flywheel is:
ω = angular velocity [rad s-1]
Nrpm = rotational speed of the flywheel [revolutions per minute]
Coefficient of Fluctuation of Energy
This is defined as the maximum fluctuation of energy to the work done per cycle.
|Six Cylinder 4-stroke gas engine||0.031|
|Four cylinder 4-stroke gas engine||0.066|
|Cross-compound steam engine||0.096|
|Single cylinder double acting steam engine||0.21|
|Single cylinder 4-stroke gas engine||1.93|
Coefficient of Fluctuation of Speed
The ratio of the maximum fluctuation of speed (maximum speed - minimum speed) to the mean speed.
|Spinning machinery||0.1 to 0.02|
|Pumping machines||0.03 to 0.05|
|Direct drive electric machines||0.002|
The energy stored in a flywheel is:
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:
Eengine = energy from engine per revolution [J]
P = engine power [W]
Nrpm = engine rotational speed [revolutions per minute]
Maximum Fluctuation of Speed
Difference between maximum and minimum speeds during a cycle.
"Theory and Design of Automotive Engines", B Dinesh Prabhu, Assistant Professor, P E S College of Engineering, Mandya, KARNATAKA