morse test final

8/19/2019 Morse Test Final

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MORSE TEST

Introduction: - The basic task in the design and development of

I.C.Engines is to reduce the cost of production and improve the

efficiency and power output. In order to achieve the above task, the

engineer has to compare the engine developed by him with other

engines in terms of its output and efficiency. Hence he has to test the

engine and make measurements of relevant parameters that reflect the

performance of the engine. In general the nature and number of tests

to be carried out depend on a large number of factors. In this chapter

only certain basic as well as important measurements and tests are

described.

Important Performance Parameters of I.C.Engines:- The

important performance parameters of I.C. engines are as follows:

Friction Power,

Indicated Power,

Brake Power,

Specific Fuel Consumption,


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Air – Fuel ratio

Thermal Efficiency

Mechanical Efficiency,

Volumetric Efficiency,

Exhaust gas emissions,

Noise

1.3. Measurement of Performance Parameters in a Laboratory

1.3.1. Measurement of Friction Power:- Friction power includes the

frictional losses and the pumping losses. During suction and exhaust

strokes the piston must move against a gaseous pressure and power

required to do this is called the “pumping losses”. The

friction loss is made up of the energy loss due to friction

between the piston and cylinder walls, piston rings and

cylinder walls, and between the crank shaft and camshaft and

their bearings, as well as by the loss incurred by driving the

essential accessories, such as water pump, ignition unit etc.


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Following methods are used in the laboratory to measure

friction

power:

Willan’s line method;

From the measurement of indicated power and brake power;

Motoring test;

Retardation test;

Morse Test.

1.3.1.2.From the Measurement of Indicated Power and Brake

Power:- This is an ideal method by which friction power is obtained

by computing the difference between the indicated power and brake

power. The indicated power is obtained from an indicator diagramand brake power is obtained by a brake dynamometer. This method

requires elaborate equipment to obtain accurate indicator diagrams at

high speeds.


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1.3.1.3.Morse Test:- This method can be used only for multi –

cylinder IC engines. The Morse test consists of obtaining indicated

power of the engine without any elaborate equipment. The test

consists of making, in turn, each cylinder of the engine inoperativeand noting the reduction in brake power developed. In a petrol engine

(gasoline engine), each cylinder is rendered inoperative by

“shorting” the spark plug of the cylinder to be made inoperative. In a

Diesel engine, a particular cylinder is made inoperative by cutting off

the supply of fuel. It is assumed that pumping and friction are the

same when the cylinder is inoperative as well as during firing.

In this test, the engine is first run at the required speed and the brake

power is measured. Next, one cylinder is cut off by short circuiting

the spark plug if it is a petrol engine or by cutting of the fuel supply if

it is a diesel engine. Since one of the cylinders is cut of from

producing power, the speed of the engine will change. The engine

speed is brought to its original value by reducing the load on the

engine. This will ensure that the frictional power is the same.

If there are k cylinders, then

Total indicated power

when all the cylinders are working = ip1 + ip2 + ip3 + …………...+ ipk

= ip j

j = 1

We can write ip j = Bt + Ft ………………………………………..(1)


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Similarly we can find the indicated power of all the cylinders, viz.,

ip2, ip3, …..ipk. Then the total indicated power is calculated as

(ip)total = ip j ……………………………………….(4)

j = 1

The frictional power of the engine is therefore given by

Ft = (ip)total – Bt ……………………………………(5)

The procedure is illustrated by some examples worked out at the endof the chapter.


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NEED OF MORSE TEST

The i.p. and the mechanical efficiency of a multi-cylinder auto engine

is found out in a veryshort time by this test. During the test the engine is run at a constant

speed and at same throttle

opening. First the b.p. of the engine with all cylinders operative is

measured by means of

dynamometer. Next, the b.p. of the engine is measured with each

cylinder rendered inoperative

one by one by shorting the spark plug in case of petrol engine or by

cutting off the fuel supply

in case of diesel engine.

hen any cylinder is rendered inoperative, the speed abruptly goes

down. !efore taking

any reading, the initial speed must be restored by ad"usting the load.

#t is assumed that the f.p. of the inoperative cylinder remains the same

as it were when the

cylinder was operative. $onsidering the case of a %-cylinder engine,


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6 MEASUREMENT OF I.P OF MULTI-CYLINDER ENGINE (MORSE

TEST)

This method is used in multi-cylinder engines to measure I.P with out the use of

indicator. The BP of the engine is measured by cutting off each cylinder in turn.

If the engine consists of 4-cylinders, then the BP of the engine should be

measured four times cutting each cylinder turn by turn. This is applicable to

petrol as well as for diesel engines. The cylinder of a petrol engine is made

inoperative by “shorting” the spark plug whereas in case of diesel engine, fuel

supply is cut-off to the required cylinder.

If there are ‘n’ cylinders in an engine and all are working, then (B.P)n = (I.P)n –

(F.P)n

Where F.P is the frictional power per cylinder.


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If one cylinder is inoperative then the power developed by that cylinder (IP) is

lost and the speed of the engine will fall as the load on the engine remains the

same. The engine speed can be resorted to its original value by reducing theload on the engine by keeping throttle position same. This is necessary to

maintain the FP constant, because it is assumed that the FP is independent of

load and depends only on speed of the engine.

When cylinder “1” is cut off; then

(B.P)n – 1

= (I.P)n – 1

– (F.P)n …..(12)

By subtracting Eq. (23.7) from Eq.(23.6), we obtain the IP of the cylinder which

is not firing i.e., (B.P)n – (B.P)n-1 = (IP)n – (IP)n-1 = I.P1

Similarly IP of all other cylinders can be measured one by one then the sum of

IPs of all cylinders will be the total IP of the engine.

This method of obtaining IP of the multicylinder engine is known as ‘Morse

Test’.

Illustrative examples:


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20.9

(ii) mech = -------------

=

---------=0.833=83.3 %

(ip)total

25.1

60,000 Bt

60,000 x 20.9

(iii) bmep = ---------------

=--------------------------------------------------

L A n K

0.09x(/4)x 0.0752 x (3000 / 2) x 4

= 5.25 x 105 N / m

2 = 5.25 bar.

MORSE TEST ON MULTI CYLINDER

PETROL ENGINE

Ex.No. : Date:


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Aim :

To conduct morse test on given multi cylinder petrol engine in order to

determine the indicated power developed in the each cylinder of the engine and

to determine the mechanical efficiency.

Apparatus Required :

*ulti cylinder petrol engine with ignition cut off arrangement

+oading arrangements

Tachometer

Theory and Description :

For slow speed engine the indicated power is directly calculated from the

indicator diagram. !ut in modern high speed engines , it is difficult to obtain

accurate indicator diagram due to inertia forces , and therefore , this method

cannot be applied . #n such cases the morse test can be used to measure the

indicated power and mechanical efficiency of multi cylinder engines . Theengines test is carried out as follows . The engine is run at maximum load at

certain speed . The !. is then measured when all cylinders are working .

Then one cylinder is made in operative by cutting off the ignition to that

cylinder . s a result of this the speed of the engine will decrease . Therefore ,

the load on the engine is reduced so that the engine speed is restored to its initial

value . The assumption made on the test is that frictional power is depends onthe speed and not upon the load on the engine .


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Definitions :

Break poer : !B"#

The useful power available at the crank shaft of the engine is called brake power

of the engine . The brake power of the engine are determined by

.

/ope brake dynamometer.

T 0 /e

0 net load

/e

0 effective radius of the brake drum

1.

rony brake dynamometer

T 0 +


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0 +oad

+

0 Distance at which the load is applied

$%ser&ation and Ta%u'ation :

'(

!rake power !. 0........... 2

'1(

/ated 3peed N 0.........../pm

'4(

Type of loading 5 0...........


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'%(

/adius of brake drum 5 / 0........... 6m7

'8(

/adius of /ope r 0 0........... 6m7

'9(

Number of cylinders 0 %


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( No

)onditions

*oadin+

(peed

B" ,-W

W/ k+

W0

W/ 1 W0

Net 'oad

Rpm

k+

k+


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W in ,N

/

A'' cy'inders are

orkin+

0

2irst

cy'inder


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as cut off and

remainin+ are in


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orkin+

3

(econd

cy'inder

as cut off and


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remainin+ are in

orkin+

4

Third

cy'inder


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as cut off and

remainin+ are in


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orkin+

5

2ourth

cy'inder

as cut off and


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remainin+ are in

orkin+

Note 5 The speed should be same for all readings

4. :ydraulic dynamometer !. 0 N


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$

0 +oad

N 0 3peed in /*

$ 0 Dynamometer constant

%. ;lectrical dynamometer

6ndicated poer : ! 6 " #

The power actually developed inside the engine cylinder due to the combustion

of the fuel are called indicated power .

# 0 F < ! & F 0 Frictional power

2rictiona' poer !2"# :

The power loss due to friction between the moving parts are called as frictional

power .

Mechanica' efficiency : !ηmech #

#t is defined as the ratio of !rake power to indicated power .


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0

9= x === x 1.8

0

[email protected] N-m

1 ? x 1===

T

0

./e

3ay /e 0 =.%m

...

0

T>>

0

[email protected] 0

%@.1N

/e


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=.%

B

8= N


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max 5 load that can be given to the engine was

C8

w 0

C8 x 8=

0 1.8N

==

max

0

net load 0

1.8 0

.18kg

=


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$heck the engine for fuel availability, lubricant and cooling water

connections .

/elease the load completely on the engine and start the engine in no loadconditions and allow the engine to run for few minutes to attain the rated

speed.

pply the load and increase the load upto maximum load. 'll four

cylinders should be in working ( . Now note the load on the engine and

speed of the engine say the speed is

6N7 rpm

$ut-off the ignition of first cylinder, Now the speed of engine decreased .

/educe the load on the engine and bring the speed of the engine to 6N7 rpm.

Now note the load on the engine.

!ring the all four cylinders are in working conditions and cut off the 1nd , 4rd

and %th

cylinder in turn and ad"ust the load to maintain same 6N7 rpm and

note the load .

Resu't:

*orse test was conducted on given petrol engine and indicated power

developed in each cylinder are determined and mechanical efficiency are

also determined .


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morse test final

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