Flywheel - nptel

speed of a shaft caused by torque fluctuations. If the source of the driving torque or load torque is fluctuating in nature, then a flywheel is usually called for. Many machines have load patterns that cause the torque time function to vary over the cycle. Internal combustion engines with one or two cylinders are a typical example.
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Machine Design II

Prof. K.Gopinath & Prof. M.M.Mayuram

Flywheel

A

flywheel

energy when it

is

and the

during

an

inertial

serves

supply the

as

of

energy-storage

a

energy

period

when

device.

reservoir,

storing

is

than

more

the

absorbs

energy

the

requirement

It

of

during

requirement energy

is

mechanical the

and

more

period releases

than

the

supply.

Flywheels-Function need and Operation The main function of a fly wheel is to smoothen out variations in the speed

of

a

shaft

caused

by

torque

fluctuations.

If

the

source

of

the

driving torque or load torque is fluctuating in nature, then a flywheel is usually

called

torque

time

engines

for.

Many

function

with

compressors,

one punch

to or

machines vary two

presses,

have

over

the

cylinders rock

load

patterns

cycle.

are

a

crushers

etc.

that

cause

Internal typical are

combustion

example.

the

the

Piston

other

systems

its

angular

that have fly wheel. Flywheel

absorbs

mechanical

energy

by

increasing

velocity and delivers the stored energy by decreasing its velocity 1 CYCLE

T2 Tm T1

B

A

D

θ

C D

θ

C

ω max ω min

A

B

Figure 3.3.1

Indian Institute of Technology Madras

Machine Design II

Prof. K.Gopinath & Prof. M.M.Mayuram

Design Approach There are two stages to the design of a flywheel. First,

the

smoothening

amount must

of

be

energy

found

required

and

the

for

(mass)

the

desired

moment

of

degree

of

inertia

needed

caters

the

required

and

safe

to absorb that energy determined. Then

flywheel

moment

of

geometry

inertia

in

must

a

be

reasonably

defined sized

that

package

is

against

failure at the designed speeds of operation.

Design Parameters Flywheel

inertia

(size)

needed

directly

depends

upon

the

acceptable

changes in the speed.

Speed fluctuation The

change

in

the

shaft

speed

during

a

cycle

is

called

the