• Sanyam

MemberMar 30, 2013

## Why a Fly Wheel is named so?

Can you explain the origin of the name flywheel and why is it called so? Also help me understand the significance of a flywheel and its uses.

The term "flywheel" comes from the combination of two words: "fly" and "wheel."

A flywheel is a mechanical device used to store rotational energy. It typically consists of a heavy disc or wheel with a high moment of inertia, mounted on a shaft. When force is applied to the flywheel, it starts rotating, and due to its high moment of inertia, it can store a significant amount of kinetic energy. This stored energy can then be used to smooth out variations in the speed of a machine or provide consistent rotational energy in systems where the energy input is intermittent.

Here's the breakdown of why it's called a flywheel:

1. "Fly": The term "fly" here does not refer to the insect but rather to the old English word "fleógan," meaning "to move through the air swiftly." In the context of the flywheel, "fly" refers to the rotational movement of the wheel.

2. "Wheel": A flywheel is typically designed in the shape of a disc or wheel, and its primary function is related to rotational motion.

So, when you put these two words together, you get "flywheel," which refers to a rotating wheel designed to store kinetic energy and act as a stabilizing force in mechanical systems.

## Uses of a flywheel:

1. Energy Storage: One of the primary purposes of a flywheel is to store kinetic energy. When an external force (such as a motor or engine) applies torque to the flywheel, it starts rotating and accumulates energy. This stored energy can then be used to provide continuous power, even when the input source of energy is intermittent or fluctuating.

2. Stabilizing Force: In many mechanical systems, especially in engines and machinery, flywheels act as stabilizing forces. They help to smoothen out variations in the rotational speed caused by the cyclical nature of power sources (e.g., piston engines), providing a more constant output.

3. Inertia: Flywheels possess high moments of inertia due to their mass and distribution. This characteristic allows them to resist changes in their rotational speed, making them useful in maintaining steady motion and reducing vibrations.

4. Mechanical Systems: Flywheels are utilized in various mechanical systems, such as clock mechanisms, power generation systems, and industrial machinery, to ensure stability and energy management.

## Uses of Flywheel in IC Engines

Use in IC (Internal Combustion) Engines:

In internal combustion engines, flywheels play a crucial role in maintaining the engine's smooth operation and overall performance. Here's how they are used in IC engines:

1. Crankshaft Balancing: In a reciprocating engine, the pistons move up and down, creating reciprocating motion. This motion generates oscillations and vibrations that can negatively impact engine operation. The flywheel is mounted on the crankshaft and helps balance these forces by storing and releasing rotational energy. As the engine produces power during the combustion stroke, the flywheel stores some of this energy, and during the other strokes, it releases this energy back to counteract the forces and reduce vibrations.

2. Starting Assistance: Flywheels also aid in starting the engine. During the ignition process, the engine needs to overcome its own internal resistance to start. The flywheel's stored energy helps in overcoming this initial resistance, providing the necessary torque to get the engine turning.

3. Load Compensation: In applications where the engine load might vary (e.g., in vehicles going uphill or carrying heavy loads), the flywheel assists in maintaining a more consistent rotational speed and power output, helping the engine run more efficiently.

I hope this answers your question. Let me know if you have follow-up questions.

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Replies

That's interesting question. I believe the reason lies in the nature of operation of a flywheel. A typical flywheel would be floating in space without any friction and storing energy by virtue of its rotational speed. But for practical purposes a flywheel would be mounted along its axis with the use of special bearings to minimise the friction.

So, it'd be a wheel that flies in the air and stores energy - maybe that's why it's called Fly Wheel.

That leads to another question related to flywheels in my mind - I've not heard of any practical (or industrial) application of Flywheel. My best guess is that it's used in automobiles. Can someone tell me where exactly is flywheel used and what type of bearings are used? Also, what are the typical sizes of flywheels?
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• MemberMar 30, 2013

Because it is a wheel which works as an inertial energy storage device, it absorbs mechanical energy and serves as reservoir, storing energy when the requirement is above the desirable amount, and then utilizing that extra amount when their is a lack of energy. basically the main function is to smoothen out the variations in the speed of the crank-shaft caused by torque variations. In general i can say that it is a wheel which flies while storing energy.
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• MemberMar 30, 2013

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• MemberMar 30, 2013

Plz tell me how to ask query from a member??
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• MemberMar 30, 2013

Thanks all for Replying.. actually I was also thinking that it files in air, without any friction is the reason it's called flywheel, but I need some one who could confirm this..!!
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• MemberMar 31, 2013

Flywheels are essentially inertial systems. They can be tiny but running at very high rpm as gyro compasses in space ships do.
They have no function except as inertial masses.
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• MemberMar 31, 2013

atul-namdeo
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• MemberApr 1, 2013

I think this video of Leonardo Da Vinci's flywheel might illustrate where the name came from.
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• MemberApr 1, 2013

A.V.Ramani
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