What is a Flywheel?
Generally, a flywheel is the perfectly rigid circular element that is mounted on the crankshaft of the engine, or a rotating shaft subjected to transfer the power. The flywheel function is to control the fluctuation in the rotating element. The flywheel has a high mass moment of inertia, due to this, it has the ability to absorb and release a high amount of energy whenever required.
Many machines have load patterns that cause the torque time function to vary over the cycle. So, to overcome this type of condition the flywheel is the best solution. As Cast iron is cheap, mostly cast iron is used for the manufacturing of the flywheel. For longer life steel can also be used, as it has properties of high strength and anticorrosion, making it durable
The Function of the Flywheel
In general, flywheel functions are to provide smooth power output in case of the fluctuating mode of an energy resource (for example IC engine, Steam engine) or to provide a sufficiently large amount of energy in a short period of time. Based on this the main functions of the flywheel are as follows:
- To minimize the jerk in the machine element
- To store the excessive amount of rotational kinetic energy when the machine is in idling or no-load condition
- To supply a large amount of energy in the minimum time.
- Balancing the rotating element mounted on the same haft but in a different plane
Working Principle of Flywheel
The main working principle of the flywheel is based on the Rotational mass moment of inertia, Where the rotational kinetic energy is stored and released in the wheel, when the wheel store kinetic energy the rotational speed of the wheel gets increases. When the demand for high energy is required, the Wheel releases its kinetic energy and the wheel's speed gets slower.
The Kinetic energy stored on the flywheel depends on the mass moment of inertia and the speed of the flywheel. The energy stored in the flywheel is given by the equation
Kinetic Energy= (1/2) I ω2
- Where, I – Mass moment of inertia
ω– Mean angular speed of the wheel
As speed changes kinetic energy associated with the flywheel also changes, the change in the kinetic energy of the flywheel is given
Change in Kinetic Energy= Kinetic energy at initial−Kinetic energy at final
Change in Kinetic Energy= (1/2) I ωi2 - (1/2) I ωf2
Δ K.E.= (1/2) I ω2 [(𝜔i− 𝜔f)/𝜔]
- 𝜔i- The initial angular speed of the wheel,
- 𝜔f- Final angular speed of the wheel
Type of Flywheel
As per our requirement, availability of space and design point of view flywheel can be classified into the following type:
- Rim type flywheel – Used for low Speed
Moment of inertial for Rim type flywheel is given by: I= (MR2)/2
- Rim and Spook type flywheel – For medium speed
- Disc type flywheel – For high speed
Moment of inertial for Rim type flywheel is given by: I = MR2
The main uses of the flywheel are as follows:
- IC Engine, Steam engine – In this case flywheel stores a fluctuating form of energy and supply smooth and less fluctuating power in the output
- Diesel generator
- Punching and blanking operation – In this case, a smooth input energy source is there, but with the help of a flywheel, we generate a high amount of energy in less time.
- Gyroscope – Applying a flywheel in a gyroscope is to maintain stability and control the direction, where friction is not dominant. For example – satellite direction is controlled by using the flywheel in the gyroscope
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