2. Flywheel
A rotating mechanical device that is used to store rotational
energy.
A flywheel is used in machines , serves as a reservoir which
stores energy during the period where the supply of energy is
more than the requirement.
Conversely, a flywheel releases stored energy by applying
torque to a mechanical load, thereby decreasing the flywheel's
rotational speed.
3. Flywheel
during In other words it can be defined as “it stores energy
power stroke and delivers during idle strokes”.
A little considerations will show that when the flywheel
absorbs energy, its speed increases and when it releases, the
speed decreases. Hence a flywheel does not maintain a constant
speed, it simply reduces the fluctuation of speed.
The flywheel’s position is between the engine and clutch patch
to the starter.
5. A Flywheel is used to maintain constant angular velocity
of the crankshaft in a reciprocating engine. In this case,
the flywheel—which is mounted on the crankshaft—
stores energy when torque is exerted on it by a
firing piston and it releases energy to its mechanical loads
when no piston is exerting torque on it.
6. Function of Flywheel
1. Flywheel absorbs energy, its speed increases and when it
releases energy, the speed decreases.
2. Hence a flywheel does not maintain a constant speed, it
simply reduces the fluctuation of speed.
3. In other words, a flywheel controls the speed variations
caused by the fluctuation of the engine turning moment
during each cycle of operation.
7. Application of Flywheel
1. Flywheel is used to maintain constant angular velocity of the crankshaft
in reciprocating Engine.
2. Flywheel is used to provide continuous energy in systems where the
energy source not continuous.
3. A flywheel is used to supply intermittent pulses of energy at transfer
rate that exceed the ability of its energy source.
4. Flywheel is used in riveting machine to store energy from the motor.
5. Flywheel is used to orient satellite instrument without the use of thruster
rocket.
9. Turning Moment Diagram for
single cylinder 4-Stroke I.C Engine:-
A turning moment diagram for a four stroke cycle internal combustion
engine is shown in Fig. We know that in a four stroke cycle internal
combustion engine, there is one working stroke after the crank has turned
through two revolutions, i.e. 720° (or 4 π radians).
Since the pressure inside the engine cylinder is less than the atmospheric
pressure during the suction stroke, therefore a negative loop is formed as
shown in Fig.
10. Turning Moment Diagram for
single cylinder 4-Stroke I.C Engine:-
During the compression stroke, the work is done on the gases,
therefore a higher negative loop is obtained.
During the expansion or working stroke, the fuel burns and the
gases expand, therefore a large positive loop is obtained. In this
stroke, the work is done by the gases.
During exhaust stroke, the work is done on the gases, therefore
a negative loop is formed.
It may be noted that the effect of the inertia forces on the piston
is taken into account in Fig.
12. Coefficient of fluctuation of speed::-
The difference between the maximum and minimum speeds during a cycle
is called the maximum fluctuation of speed. The ratio of the maximum
fluctuation of speed to the mean speed is called the coefficient of
fluctuation of speed.
Let N1 and N2 = Maximum and minimum speeds in r.p.m. during the
cycle, and
13. Advance and Modern Flywheel
Flywheels have also been proposed as a power booster for
electric vehicles. Speeds of 100,000 rpm have been used to
achieve very high power densities.
Modern high energy flywheels use composite rotors made with
carbon-fibre materials. The rotors have a very high strength-to-
density ratio, and rotate at speeds up to 100,000 rpm. in a
vacuum chamber to minimize aerodynamic losses.
14. Disadvantages
There are safety concerns associated with flywheels due to
their high speed rotor and the possibility of it breaking
loose & releasing all of it's energy in an uncontrolled
manner.
Its Bulkier, adds more weight to the vehicle.
