Flywheel free study notes for Diploma/BTech.

1. What is Flywheel ?

A flywheel is a heavy rotating mechanical device used to store energy and regulate speed fluctuations in machines.

Key Idea

  • Stores energy when supply > demand
  • Releases energy when demand > supply
  • Maintains nearly uniform angular speed

2. Function of a Flywheel

  • Reduces fluctuation of speed
  • Stores rotational energy
  • Supplies energy during low power strokes
  • Improves machine efficiency and smoothness

Common Applications

  • Internal combustion engines
  • Reciprocating engines
  • Punching and shearing machines
  • Rolling mills

3. Principle of Working

E=12Iฯ‰2E = \frac{1}{2} I \omega^2E=21โ€‹Iฯ‰2

Where:

  • EEE = energy stored
  • III = mass moment of inertia
  • ฯ‰\omegaฯ‰ = angular velocity

Working Explanation

  • During power stroke โ†’ energy stored
  • During idle stroke โ†’ energy released
  • Thus, speed remains nearly constant

4. Construction of Flywheel

7

Main Parts

  1. Rim
    • Outer heavy ring
    • Stores most of the energy
  2. Hub
    • Central portion
    • Mounted on shaft
  3. Arms (Spokes)
    • Connect rim and hub
    • Provide structural support

5. Types of Flywheels

(a) Solid Disc Flywheel

  • Simple construction
  • Used in small machines

(b) Rim Type Flywheel

  • Heavy rim with spokes
  • Stores more energy
  • Widely used in engines

(c) High-Speed Flywheel

  • Made of advanced materials
  • Used in modern energy storage systems

6. Coefficient of Fluctuation

(a) Coefficient of Speed Fluctuation

Cs=Nmaxโˆ’NminNmeanC_s = \frac{N_{max} – N_{min}}{N_{mean}}

(b) Coefficient of Energy Fluctuation

Ce=Emaxโˆ’EminEmeanC_e = \frac{E_{max} – E_{min}}{E_{mean}}

7. Energy Storage in Flywheel

ฮ”E=Iฯ‰2Cs\Delta E = I \omega^2 C_s

  • ฮ”E\Delta Eฮ”E = maximum fluctuation of energy
  • CsC_sCsโ€‹ = coefficient of speed fluctuation

Important Insight

  • Larger inertia โ†’ more energy storage
  • Heavier rim โ†’ better performance

8. Turning Moment Diagram

  • Shows variation of torque with crank angle
  • Area above mean torque line โ†’ energy stored
  • Area below โ†’ energy released

9. Flywheel vs Governor

FeatureFlywheelGovernor
FunctionControls speed fluctuationControls mean speed
ActionStores/releases energyRegulates fuel supply
ApplicationCyclic machinesEngines

10. Advantages of Flywheel

  • Smooth operation
  • Reduces vibration
  • Improves machine life
  • Stores energy efficiently

11. Disadvantages of Flywheel

  • Heavy and bulky
  • Requires space
  • Initial cost is high
  • Risk at high speeds (bursting)

12. Applications of Flywheel

  • IC engines (cars, bikes)
  • Steam engines
  • Punch presses
  • Power plants
  • Renewable energy storage systems

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