In a turning moment diagram, the variations of energy above and below the mean resisting torque line is called

Explanation:

Fluctuation of Energy in a Turning Moment Diagram

• In a turning moment diagram, the term fluctuation of energy refers to the variations in energy levels above and below the mean resisting torque line. These variations occur due to the periodic nature of the torque generated by the engine during one complete cycle of operation. The fluctuation of energy is a crucial concept in the design of flywheels, which are used to smooth out these variations and ensure uniform operation.

In any reciprocating engine, the torque produced is not constant throughout the cycle. Instead, it varies depending on the position of the crank and the forces acting during different stages of the engine’s operation, such as suction, compression, expansion, and exhaust. This variation creates regions in the turning moment diagram where the energy is higher or lower than the mean resisting torque line. These regions are referred to as:

• Surplus Energy: When the torque is higher than the mean torque, the engine generates surplus energy, which is stored in the flywheel.
• Deficit Energy: When the torque is lower than the mean torque, the flywheel releases the stored energy to compensate for the deficit.

The difference between the maximum and minimum energy levels in the turning moment diagram is called the maximum fluctuation of energy. This value is critical in determining the size and mass of the flywheel required to maintain smooth engine operation.

Role of Fluctuation of Energy:

• The fluctuation of energy plays a significant role in mechanical systems that rely on reciprocating engines. Without a mechanism to manage these fluctuations, the engine's operation would be jerky, leading to inefficiencies and potential damage to the connected machinery. The flywheel is the component designed to address this issue. By absorbing surplus energy and releasing it during deficit phases, the flywheel ensures a uniform delivery of power to the output shaft.