Flywheel Notes

Flywheel is an inertial energy-storage device, acts as a reservoir of energy, which stores energy during the period when supply of energy is more than requirement and release it during the period when supply is less than the requirement.
It does not control the speed variations caused by the varying load.

Speed Fluctuation

• The difference between the maximum and minimum speed during a cycle is called the speed fluctuation and is equal to $ω_{max} - ω_{min}$.

• The ratio of maximum fluctuation of speed to the mean speed is called coefficient of fluctuation of speed (Cs).

\[C_s = \frac{ω_{max} - ω_{min}}{ω}\]

• The reciprocal of the coefficient of fluctuation of speed is known as coefficient of steadiness.

Energy Fluctuation

The kinetic energy Ek in a rotating system 

\[E_k = \frac{1}{2}Iω^2\]

Hence the change in kinetic energy ($e = \triangle E_k$) of a system can be written as

\[e = \frac{1}{2}I(ω^2_{max} - ω^2_{min})\]

\[e = \frac{(ω_{max} + ω_{min})}{2}I(ω_{max} - ω_{min}) = I(ω)(C_s ω) = I C_s ω^2\]

\[\boxed{I = \frac{e}{C_s ω^2}} \]

• Coefficient of fluctuation Energy (Ce) is defined as

\[C_e = \frac{e}{work-done-per-cycle}\]

Turning Moment Diagram

• Work done per cycle is = $T_{mean} * θ$.

Related Post:

1. CAM Follower

2. Gear Train