What is flywheel?
A flywheel is a heavy rotating body which acts as a reservoir of energy. It acts as a bank of energy between the energy source and machinery.
Energy stored in a flywheel is in the form of kinetic energy.
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Functions of flywheel
- It is used to store energy when available and supply it when required.
- To reduces speed fluctuations.
- To reduce power capacity of electric motor or engine.
Applications of the flywheel can be broadly divided into two parts based on source of power available and the type of driven machinery.
Applications of flywheel
- When the power available at variable rate but is required at uniform rate. For e.g. the machinery driven by reciprocating internal combustion engine.
- When the power is available at uniform rate but we need it at non-uniform rate. For e.g. power required in punching press. In this case we need sudden power at punching stroke.
Types of flywheels
On the basis of angular velocity, flywheels can be divided into two types.
High velocity flywheels
For angular velocity above 10000 to 100000 RPM
Low velocity flywheels
For angular velocity below 10000 RPM
Difference between flywheel and governor
Many people confuse between flywheel and governor, but they are totally two different things. Here are some differences between a them.
- A flywheel is used to mitigate cyclic fluctuations in available energy but a governor is used to adjust the supply of fuel as per the load.
- The energy stored in flywheel is kinetic which is 100% available but governor mechanism involves friction.
- Flywheel is not used when cyclic fluctuation of energy is small or negligible. While a governor is necessary for all the types of engines because it limits the fuel supply as per demand.
- If we have constant load then governor will remain idle but due to cyclic fluctuations in energy available, flywheel will always work.
- Governor has no influence in cyclic fluctuations in energy and flywheel has no influence on the mean speed of engine.
- Governor controls mean speed of the engine and flywheel controls cyclic fluctuations in energy.
Advantages of flywheel
- Less overall cost
- High energy storage capacity
- High power output
- They are safe, reliable, energy efficient, durable
- It is independent of working temperatures
- Low and inexpensive maintenance
- High energy density
Limitations of flywheel
- They can take a lot of space
- They are expensive to manufacture
- Building material is always a limitation for it
Uses of flywheel
- In reciprocating internal combustion engines
- In wind turbines
- In locomotive propulsion system
- In satellites to control directions
- In Mechanical workshops
- In punching machines