thermal & hydro lab expmnts

Thermal and Hydro Lab Manual

1

Experiment Number: 1 Date:

DETERMINATION OF COEFFICIENT OF IMPACT OF A JET STRIKING A FLAT VANE

AIM: To determine the coefficient of impact on the flat vane

APPARATUS

1. Impact of jet test rig

2. Weights

3. Stop watch

PROCEDURE

1. Fix a vertical flat vane.2. Start the supply and adjust the flow in such a manner that the jet of water through the

nozzle impinge on the vane displacing it from its position.3. The force due to impact of vane will be acting on the vane in upward direction. Note down the reading on the scale.4. Place a removable weight to bring back the vane to equilibrium position and note down the

reading on the scale.5. Measure the discharge by measuring the water level rise (h) in the collecting tank for a particular time (t).6. Repeat the procedure for different discharges.

FORMULAE

1. Discharge, Q= Ah/t

2. Velocity, V = Q/a

3. Counter weight, W= mg

4. Theoretical force, Fth = ρaV2

5. Actual force, Fact =

6. Coefficient of impact, k = Fact / Fth

where, A = Area of collecting tank = 0.25 m2

a = Area of jet = (0.01)2

d= diameter of jet = 1cm = 0.01 m

h = rise of water level in the collecting tank = 0.1 m

m= mass of removable load in kg

2 Thermal and Hydro Lab Manual

ρ = density of water = 1000 kg/ m3

Fig. 1.1 Impact of jet test rig


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TABLE.1.1 Determination of coefficient of impact of a jet striking a flat vane

S.N

o.

Tim

e fo

r10

cm r

ise

ofw

ater

t (

s)

Dis

char

geQ

(m3 /s

)

Vel

ocit

yV

(m/s

)

The

oret

ical

for

ceF

th

(N)

Cou

nter

wei

ght

W

(N)

x 1(c

m)

x 2(c

m)

dx (cm

)

Act

ual f

orce

Fac

t

(N)

Coe

ffic

ient

of

impa

ctk

(No

unit

)

1

2

3

4

PRECAUTIONS

1. Note down the readings without parallax error.2. The discharge should be changed gradually so as not to imbalance the vane suddenly.

RESULT

The coefficient of impact on flat vane is determined as, k = ………. (no units)

VIVA QUESTIONS:

1. Define the terms (a) Impact of jets and (b) Jet propulsion. 2. What is the force exerted and work done by a jet on a series of vanes? 3. What is the efficiency of a series of vanes? 4. Draw the velocity triangle for a jet striking a moving curved vane.


5. What is the velocity and relative velocity of the jet?

REMARKS:


5

Signature of the Faculty Incharge


DETERMINATION OF EFFICIENCY OF A RECIPROCATING PUMP

AIM: To find the efficiency and draw the performance curves of a reciprocating pump

APPARATUS

1. Reciprocating pump set up2. Sump3. Stopwatch4. Tachometer

THEORY

A reciprocating pump essentially consists of a piston or plunger which moves to and fro in a closed fitting cylinder. Atypical double acting cylinder is connected to suction and delivery pipes, each of which is provided with a non return valve. The piston is connected to a crank by means of connecting rod. During the suction stroke, the crank rotates from 0 to 180 degrees and a partial vacuum is created in the cylinder, which enables the atmospheric pressure acting on the liquid surface to force the liquid up to the suction and fill the cylinder by opening the suction valve. During the delivery stroke the crank rotates 180º to 360º and the piston forces the water to go out of the cylinder through the delivery valve. The operating characteristic curves of a reciprocating pump are obtained by plotting the discharge, power input, and overall efficiency against the head developed by the pump when it is operating at constant speed.

Fig. 2.1 Reciprocating pump


PROCEDURE1. The pump is filled with sufficient amount of water and the pump is primed if necessary. 2. The delivery valve is kept open and the pump is started and is run at a particular speed. The

speed of the pump is measured with the help of a tachometer.3.The actual discharge Q is measured by noting the time taken for a rise in 10cm height of

water in the measuring tank.4. The input power is calculated by noting the time taken for 5 revolutions of the energy meter disc.5. Suction and delivery pressures are noted from the pressure gauges.6. Position of delivery valve is slightly altered for different delivery pressures and take 3 or 4 sets of readings of suction pressure, delivery pressure and discharge are found.7. Characteristic curves are plotted according to the values obtained.

PRECAUTIONS1. The delivery valve should be completely closed before starting and stopping of the pump 2. Don’t start the pump when there is no water in sump tank

TABLE.2.1 Determination of efficiency of a reciprocating pump

S.No.

Pressure gauge reading

(kg/cm2)

Vacuum gauge reading

(mm of Hg)

Total head

(m of water)

Time taken for 10cm rise of water (s)

Discharge

(m3/s)

Time taken for 5 rev of energy meter disc (s)

Input power

(kW)

Output power

(kW)

Efficiency

Ƞ

%

1

2

3


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MODEL CALCULATIONS

1. Actual discharge, Q act = A x h / t (m3/s) where, A = Area of the collecting tank = 0.25 m2

h = 10 cm rise of water level in the collecting tank

t = Time taken for 10 cm rise of water level in collecting tank

2. Total head, H= (Ps/760 + Pd/1.033) x 10.33 m of water

where, Pd = Pressure gauge reading in kg /cm2

Ps= Suction pressure gauge reading in mm of Hg

3. Input power, Pi = (3600 x N x 0.8 x 0.9) / (E x T) (kW)

where, N = Number of revolutions of energy meter disc E = Energy meter constant= 100 rev / kWhr

T = time taken for ‘N’ revolutions

efficiency motor is 80%

belt transmission efficiency is 90%

4. Output power, Po = ρ x g x Q x H / 1000 (kW) where, ρ = Density of water = 1000 kg / m³

g = Acceleration due to gravity = 9.8 m / s2

H = Total head of water (m)

Q = Discharge (m3 /s)

5. Efficiency, Ƞ =( Po / Pi) x 100 %


GRAPHS:

1) Head vs Discharge

2) Head vs Efficiency

3) Head vs Power

RESULT

The performance characteristics of the reciprocating pump are studied and the efficiency is

calculated as …………… %

VIVA QUESTIONS

1. What is the function of air vessel in a reciprocating pump? 2. What are suction and delivery heads? 3. What is difference between gauge and vacuum pressure?4. Is a reciprocating pump used for high head or high discharge?5. Convert 0.5 kg/cm2 into meter of water.


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REMARKS:




DETERMINATION OF EFFICIENCY OF A CENTRIFUGAL PUMP

AIM: To find the efficiency and draw the performance curves of a centrifugal pump

APPARATUS

1. Centrifugal test rig2. Stop watch3. Collecting tank4. Piezometer5. Energy meter6. Pressure gauge7. Vacuum gauge

THEORY

A machine, which converts the mechanical energy to the hydraulic energy by means of centrifugal force, is known as centrifugal pump.

The centrifugal pump works on the principle of forced vortex flow. When certain mass of fluid is rotated by means of an external force, which results in rise of pressure of the fluid at its centre of rotation. When the radius of impeller is more, the rise in head is more and the discharge is also high . The rise in pressure head can be used to rise the fluid to a high level.


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Fig.3.1 Centrifugal pump

PROCEDURE

1. The sump is filled with sufficient amount of water keeping the delivery valve fully closed, the pump is started.

2. Priming is done for the pump before starting

3. Then the valve is slowly opened and the actual discharge is found by noting the time taken for 10 cm raise of water level.

4. The time taken for 5 revolutions of the energy meter disc is noted and by using this time the input power can be known

5. The suction and delivery pressure are noted by means of pressure gauges

6. The procedure is repeated for different set of readings

PRECAUTIONS

1. The delivery valve should be completely closed before starting and stopping of the pump

2. Priming should done for the pump before staring

TABLE : 3.1 Determination of efficiency of centrifugal pump

S.No Pressure gauge reading

(kg/cm2)

Vacuum gauge reading

(mm of Hg)

Total head

(m of water)

Time taken for 10cm rise of water (s)

Discharge

(m3/s)

Time taken for 5 rev of energy meter disc (s)

Input power

(kW)

Output power

(kW)

Efficiency

Ƞ

%

1

2


3

MODEL CALCULATIONS

1. Actual discharge, Q act = A x h / t (m3/s) where, A = Area of the collecting tank = 0.49 m2

h = 10 cm rise of water level in the collecting tank

t = Time taken for 10 cm rise of water level in collecting tank

2. Total head, H= (Ps/760 + Pd/1.033) x 10.33 m of water

where, Pd = Pressure gauge reading in kg / cm2

Ps= Suction pressure gauge reading in mm of Hg

3. Input power, Pi = (3600 x N x 0.8) / (E x T) (kW)

where, N = Number of revolutions of energy meter disc E = Energy meter constant= 100 rev / kW hr

T = time taken for ‘N’ revolutions

0.8 is motor efficiency

4. Output power, Po = ρ x g x Q x H / 1000 (kW) where, ρ = Density of water = 1000 kg / m³

g = Acceleration due to gravity = 9.8 m/s2

H = Total head of water (m)

Q = Discharge (m3/ s)

5. Efficiency, Ƞ = ( Po / Pi) x 100 %


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GRAPHS:

1) Discharge vs Head2) Discharge vs Efficiency3) Discharge vs Power

RESULT

The performance characteristics of the centrifugal pump are studied and the efficiency is

calculated as …………… %

VIVA QUESTIONS

1. What is a pump? 2. What is difference between centrifugal and reciprocating pump? 3. Which types of pumps are used for high heads? 4. Which types of pumps are used for high discharge? 5. Why the pumps are connected in parallel or series?


REMARKS:


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DETERMINATION OF COEFFICIENT OF DISCHARGE OF ORIFICEMETER

AIM: To calculate the coefficient of discharge of orifice meter

APPARATUS

1. Orifice meter Test Rig 2. Stop watch 3. Measuring Tank4. Supply tank provided with circular orifice5. Differential U-tube manometer6. Collecting tank with piezometer and control valve

THEORY

Orifice meter is a device used for measuring the rate of flow of a fluid through a pipe. It consists of a flat circular plate which has a circular sharp edged hole called orifice, which is concentric with the pipe. The apparatus is provided with a water tank and a collecting tank. Water in main tank can be driven by means of a motor through orifice meter and collected in the collecting tank. The discharge through orifice meter under ideal condition i.e. theoretical flow rate is given by

Qth=

where a1 = Cross sectional area of the inlet pipe

a0 = Cross sectional area of the orifice

g = Acceleration due to gravity

hw = Net pressure head of water

but actual discharge will be less than theoretical discharge & is given by

Qact = Cd x Qth

where Cd is coefficient of discharge of orifice meter and its value is always less than 1. So Cd

can be calculated as per the following formula

Cd =


Fig. 4.1 Orifice meter

PROCEDURE

1. The main tank is filled in with water and the motor connected to orifice meter tubes is switched ON 2. First the valve of orifice meter corresponding to throat diameter 40 mm is slightly opened so that flow through the orifice meter tube takes place.3. The pressure difference in the U- tube manometer is noted down.4. Time for 5cm rise of water in the U- tube manometer is noted down5. The value is further opened in order to attain different flow rates and the above procedure is repeated for five times and totally six readings are tabulated 6. The above procedure can be repeated for the remaining two orifice meters of throat diameters 20mm and 25 mm respectively.


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PRECAUTIONS

1. While adjusting the mercury in U-tube manometer limbs, care should be taken to avoid expelling of mercury

2. While performing the experiment on the orifice meter, the two measuring valves (remaining valves) corresponding to two Orifice meters should be closed.

3. Time taken for 5 cm rise in water level in the collecting tank should be noted carefully.

TABLE: 4.1 Determination of coefficient of discharge of orifice meter

S.No

Time taken for

10cm rise of water

(s)

Manometer readings Manometer head

hw

(m)

Actual discharge

(m3/s)

Theoretical discharge

(m3/s)

Coefficient of

discharge

Cd

h1

(cm)

h2

(cm)

1

2

3

MODEL CALCULATIONS

1. Qth=

where a1 = Cross sectional area of the pipe

a0 = Cross sectional area of the orifice

g = Acceleration due to gravity

hw = Net pressure head of water


hm = Net pressure head of mercury mano meter

Sm = Specific gravity of mercury = 13.6

Sw = Specific gravity of water = 1

D = diameter of inlet of pipe = 40mm

d = diameter of orifice = 20mm

2. Qact = A x h /t

where, A = Area of the collecting tank = 0.25 m2

h = Rise of water in collecting tank = 10 cm

t = time taken for 10cm rise of water in collecting tank (in s)

3. Cd =

where Cd = Coefficient of discharge of orifice meter

GRAPH

Qact vs Qth Take Qact on y –axis

RESULT

The co efficient of discharge through orifice meter is determined as

Cd =……… (from experiment)

=........... (from graph)

VIVA QUESTIONS:

1. Define an Orifice.

2. Define vena-contracta.

3. Write down the Bernoulli’s equation for real fluids.

4. What is difference between orifice and mouth piece?

5. What are the differences between venture and orifice meter?


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REMARKS:

Signature of the Faculty In charge



DETERMINATION OF COEFFICIENT OF DISCHARGE OF VENTURIMETER

AIM: To calculate the coefficient of discharge of Venturimeter.

APPARATUS

1. Venturimeter Test Rig 2. Stop Watch 3. Differential U-tube manometer4. Meter scale5. Collecting tank with piezometer and control valve

THEORYA Venturimeter is a device used for measuring the rate of a flow of a fluid flowing through a pipe. It consists of three parts

1) A short converging part 2) Throat 3) Diverging partIt is based on the principle of Bernoulli’s equation.The discharge through Venturimeter under ideal condition i.e. theoretical flow rate is given by

Qth =

where a1 = Cross sectional area of the inlet d1 = diameter of inlet = 25mma2 = Cross sectional area at the throatd1 = diameter of throat = 15mmg= Acceleration due to gravityhw = Net pressure head of water

hm = Net pressure head of mercury manometerSm = Specific gravity of mercury = 13.6Sw = Specific gravity of water = 1Qact = A x h / t

but actual discharge will be less than theoretical discharge & is given by

Qact = Cd x Qth


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where Cd is coefficient of discharge of Venturimeter and its value is always less than 1.

So Cd can be calculated as from the following formula

Cd =

Fig. 5.1 Venturimeter

PROCEDURE

1. The main tank is filled with water and the motor connected to Venturimeter tubes is switched ON

2. First the valve of Venturimeter corresponding to throat diameter 40mm is slightly opened so that flow through the Venturimeter takes place.

3. The pressure difference in the U–tube manometer is noted down.4. Time for 5 cm rise of water level is noted down5. The valve is further opened in order to attain different flow rates and the above

procedure is repeated for five times and totally six readings are tabulated.6. The above procedure can be repeated for the remaining two Venturimeters of throat

diameters 20mm and 25 mm respectively.

PRECAUTIONS1. While adjusting the mercury limbs in U- tube manometer care should be taken to

avoid any expelling out of mercury.2. While performing the experiment on the venturimeter the two remaining valves

corresponding to venturimeter should be closed.3. Time taken for 5cm rise in water level in the collecting tank should be noted carefully.


TABLE: 5.1 Determination of coefficient of discharge of Venturimeter

S.No

Time taken for 10cm rise of water

(s)

Manometer readingsManometer

head

hm

(m)

Actual discharge

(m3/s)

Theoretical discharge

(m3/s)

Coefficient of

discharge

Cd

h1

(cm)

h2

(cm)

1

2

3

MODEL CALCULATIONS

1. Qth=

where, a1 = Cross sectional area of the inlet d1 = diameter of inlet = 25mma2 = Cross sectional area at the throat

d2 = diameter of throat = 15mmg= Acceleration due to gravityhw = Net pressure head of water

hm = Net pressure head of mercury manometerSm = Specific gravity of mercury = 13.6Sw = Specific gravity of water = 1

2. Qact = A x h / t

where, A = Area of the collecting tank = 0. 25 m2

h = Rise of water in collecting tank in m

t = time taken for 10cm rise of water in collecting tank (in seconds)


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3. Cd =

where Cd = Coefficient of discharge of Venturimeter

GRAPH

Qact vs Qth Take Qact on y–axis

RESULT

The co efficient of discharge through venturi meter is determined as

Cd =……… (from experiment)

=........... (from graph)

VIVA QUESTIONS:

1. What is the working principle of Venturimeter 2. What are the different parts of Venturimeter? 3. What are the convergent and divergent angles of Venturimeter?4. Coefficient of discharge is high for Venturimeter or orifice meter?5. State Bernoulli’s theorem.


REMARKS:


25

Signature of the faculty


DETERMINATION OF EFFICIENCY OF PELTON WHEEL TURBINE

AIM: To find the overall efficiency and draw the performance characteristic curves of Pelton Wheel Turbine.

APPARATUS

1. Pelton wheel test rig

2. Tachometer

3. Weights

THEORY

The Pelton wheel or Pelton turbine is a tangential flow impulse turbine. The water strikes the bucket along the tangent of runner. The energy available at the runner is only kinetic energy. The pressure at the inlet and outlet of the turbine is atmospheric. This turbine is used for high heads.

The water flows from the reservoir and flows through the penstock at the outlet of which a nozzle is fitted; the nozzle increases the kinetic energy of water flowing through the penstock. At the outlet of the nozzle, the water comes out in the form of a jet and strikes the buckets of the runner. The main parts of the Pelton wheel are

1.Nozzle and flow regulating arrangement2.Runner and buckets3.Casing and braking jet


Fig. 6.1 Pelton wheel turbine

PROCEDURE

1. The sump is filled with sufficient amount of water and the pump is primed if necessary.

2. The turbine is kept in the unloaded position, gate valve and cocks of the manometer are kept constant

3. The pump is started and the gate valve is slowly opened. The amount of water striking the wheel is adjusted by keeping the spear in 1/4th open conditions

4. The speed of the turbine is measured and the manometer reading is noted. The head on the turbine is measured

5. The turbine is gradually loaded from lower to higher weights and the speed, manometer reading and the load applied are noted in each case.

6. The above procedure is repeated for ½, 3/4th and fully open conditions.

PRECAUTIONS

1. The gate valve and cocks of the manometer must be closed at the initial stage

2. Water used must be free from dust

3. Manometer readings are taken without parallax error

4. Cocks of the manometer must be opened gently

TABLE: 6.1 Determination of efficiency of Pelton Wheel Turbine


27

S.No Pressure gauge reading

Manometer readings

Speed Spring balance readings

Input power

Output power

Efficiency

P1

(kg/cm2)

h1 h2 h N

rpm

T1

kg

T2

kg

Pi

(kW)

Po

(kW)

Ƞ

(%)cm cm m

1

2

3

MODEL CALCULATIONS

1. Input Power = Water power = in kW

where, W = 9810 N/m3

in m3/s

h = Manometer reading in mm of Hg

H = in meters of water

P1 = Pressure gauge reading in kg/cm2

2. Output Power = Brake power =

where, N = Speed of brake drum dynamometer in rpm

T = (T1-T2) x 9.81 x 0.162 Nm


3. Efficiency, η= %

GRAPHS

1.Speed vs Discharge

2.Speed vs Power

3. Speed vs Efficiency

RESULT

The performance characteristic curves of Pelton Wheel Turbine are obtained.

VIVA QUESTIONS:

1. What is a turbine? 2. What is the power available at the Pelton wheel? 3. What type of turbine a Pelton wheel is? 4. What is maximum angle of deflection for the Pelton wheel bucket? 5. What is shape of Pelton wheel bucket?


29

REMARKS:



FRANCIS TURBINE

AIM: To draw the performance characteristic curves of Francis turbine.

APPARATUS

Francis turbine test rig, tachometer, weights

THEORY:

Radial flow turbines are those turbines in which the water flows in the radial direction. The water may flow radially from outwards to inwards or vice- versa. If the water flows from outwards to inwards through the runner, the turbine is known as inward flow reaction turbine.

Reaction turbine means that the water at the inlet of the turbine possesses kinetic energy as well as pressure energy. As the water flows through the runner, a part of pressure energy goes on changing into kinetic energy.

The inward flow reaction turbine having radial discharge at outlet is known as Francis turbine. In the modern Francis turbine, the water enters the turbine in the radial direction at the outlet and leaves in the axial direction at the inlet of the runner. The main parts of the turbine are

1. Casing2. Runner3. Guide mechanism4. Draft tube


Fig. 7.1 Francis turbine


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PROCEDURE

1. The sump is filled with sufficient amount of water and the pump is primed if necessary

2. The turbine is kept in the unloaded position. The gate valve and the manometer cocks are kept closed

3. The pump is started and the gate valve is slowly opened. The amount of water entering the casing is adjusted by turning the wheel connected to the guide valves

4. The speed of the turbine is measured and the manometer readings are noted. The head on the turbine is measured

5. The turbine is gradually loaded from lower to higher weights and the speed, manometer readings, load applied are noted for each step of loading

6. The above procedure is repeated for ½ ,3/4th , fully open conditions of the gate valve

PRECAUTIONS

1.Before the experiment is started, it must be checked that the gate valve and the cocks of the manometer are closed

2.The water used must be free from dust3.The cocks of the manometer must be opened gently

TABLE: 7.1 Determination of efficiency of francis turbine

S.No Gate opening

Pressure gauge reading

Manometer readings

Speed Spring balance readings

Input power

Output power

Efficiency

P1

(kg/cm2)

h1 h2 h N

rpm

T1

kg

T2

kg

Pi

(kW)

Po

(kW)

Ƞ

(%)cm cm m

1

2

3


MODEL CALCULATIONS:

1. Input power = Water power = in kW

where, W = 9810 N/m3

Q = in m3/s

84.5 = Venturimeter constant

h = Manometer reading in mm of Hg

H = x(10.33) in meters of water

P1 = Pressure gauge reading in Kg/cm2

2. Output Power = Brake power =

where, N = Speed of brake drum dynamometer in rpm

T = (T1-T2) x9.81x0.162 Nm

3. Efficiency, η= %

Unit speed, Nu =

Unit discharge Qu =

Unit power Pu =

P = Brake Power


33

GRAPHS

1.Unit speed vs Unit Discharge

2.Unit speed vs Unit Power

3. Unit Speed vs Efficiency

RESULT

The performance characteristic curves of Francis Turbine are obtained.

VIVA QUESTIONS:

1. What type of energy is used to run the Francis turbine?


2. What is the use of casing in Francis turbine? 3. What is use of a draft tube?

4. What is difference between Pelton wheel and Francis turbine?

REMARKS:


35



STUDY OF VALVE TIMING DIAGRAM OF

FOUR STROKE DIESEL ENGINE

AIM

To find the timing of inlet valve and exhaust valve opening and closing for the given

4 stroke cycle engine and represent the result through a valve timing diagram.

APPRATUS & EQUIPMENT

4 - Stroke diesel engine model Tape Chalk

THEORY

It is the graphical representation of exact movements of the two valves i.e. Inlet valve and exhaust valve as well as firing of the fuel. It is generally expressed in terms of angular position of crank shaft.

The working of 4-stroke diesel engine consists of four strokes of the piston or two complete rotations of the crank shaft. The strokes are

Suction stroke Compression stroke Power or Expansion stroke Exhaust stroke

Suction stroke

In this stroke inlet valve opens before the piston reaches top dead centre on the beginning of suction stroke. Inlet valve opens and closes after the suction is completed.

Compression stroke


During this stroke the piston moves from bottom dead centre to top dead centre. Both inlet and outlet valve remain closed.

Power stroke At the end of compression stroke the diesel oil is injected into engine cylinder with the

help of fuel valve. The diesel is injected in the form of fine spray which gets ignited due to

high temperature of the compressed air. The fuel valve closes after the piston moves from

TDC. The burnt gases at high temperature and pressure pushes the piston down words and

some of heat energy is converted into mechanical work.

Exhaust stroke

During this stroke the piston moves from BDC to TDC and at the end of this stroke

the exhaust valve closes.

PROCEDURE

The circumference of the brake drum is measured by means of the tape. The flywheel is slowly rotated in the direction of rotation with the help of the decompression lever until the piston reaches the top most position. Mark TDC (top dead centre) on the flywheel. A pointer is made to coincide with the mark. The cover of the cylinder head is removed to observe the opening and a closing of the valves from the movement of the rocker arm. The flywheel is slowly rotated in the direction of rotation and the points, at which the opening and closing of both the valves take place, are marked on the flywheel. A point corresponding to the event of opening of valve of the injection pump (from the spill of the fuel) is also marked.

A point directly below TDC representing the BDC (bottom dead centre) is marked on the flywheel. The circumferential distances of the various marks are now measureed from the TDC. They are converted into angles in degrees w.r.t. the TDC & BDC.

Fig. 8.1 Valve Timing Diagram of Four Stroke Diesel Engine


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IVO = Inlet valve opens IVC = Inlet valve closes

EVO = Exhaust valve opens EVC = Exhaust valve closes

FVO= Fuel valve opens FVC= Fuel valve closes

Table 8.1 Measurement of valve timing

S. No. Event Reference point Before/After Timing

(degrees)

1 IVO

2 IVC

3 EVO

4 EVC

5 FVO

6 FVC

RESULT

Thus the valve timing diagram of 4-stroke diesel engine is drawn.

VIVA-QUESTIONS1. How are the valves operated in a diesel engine?

2. What is the average value of compression ratio in a diesel engine?

3. What is the purpose of decompression lever?

4. Which is more volatile in nature Diesel or Petrol?

5. What is the purpose of flywheel?

6. How is mixing of air and fuel done in diesel engines?

7. How is fuel flow controlled in case of diesel engines?

8. What is the use of a governer?

9. Does scavenging process exist in diesel engines?


10. Do we use spark plug in diesel engine?


39

REMARKS:


Signature of the Faculty-In-charge


STUDY OF PORT TIMING DIAGRAM OF

TWO STROKE PETROL ENGINE

AIM

To find out the timing of inlet, transfer and exhaust port opening and closing for the

given 2-Stroke petrol engine and represent the result through port timing diagram

APPRATUS & EQUIPMENT

2 - Stroke petrol engine model Tape Chalk

THEORY

A two stroke engine performs only 2- strokes to complete one working cycle. In this the suction, compression, expansion and exhaust take place during 2-strokes of the piston. A two stroke engine has ports (holes) instead of valves.

First strokeAt the beginning of first stroke the piston is at the bottom dead center. Both the

transverse port and the exhaust port are opened. The fresh air fuel mixture flows into the

engine cylinder from the crank case. When the piston starts to move up, first it covers the

transverse port and thereafter exhaust post. The fuel is compressed as the piston moves

upwards in this stage. At the same time, inlet post opens and fresh air fuel mixture enters into

the crank case.

Second stroke

In this stroke, just before the piston reaches top dead center, the air fuel mixture is ignited with the help of a spark plug. It suddenly increases the pressure and temperature of products of combustion. Due to increase in pressure the piston is pushed downward with a great force.

PROCEDURE

1. Identify the inlet and exhaust ports.2. Throughout the experiment the rotation of the flywheel has to be in one direction

either clockwise or anti clockwise.


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3. Mark the reference point for top dead center (TDC) and Bottom dead center (BDC) on the flywheel. Rotate the flywheel until piston reaches the TDC and coincide with the exhaust port top edge. Make a mark on the fly wheel with respect to fixed point (say TDC1).Rotate the fly wheel and when the piston moves towards BDC and coincides with the same exhaust port edge, make a marking on the flywheel with respect to the fixed point (say TDC2). Measure the arc length from TDC 1 to TDC2 along the direction of rotation. Take half of this arc length and mark a line from TDC 1 along the direction of rotation, indicate the line as TDC. Take half of the circumference of the fly wheel and mark a line on the fly wheel, indicate the line as BDC.

4. The opening and closing of the inlet port, exhaust port and transfer port are marked on the fly wheel. When the piston just opens the inlet port completely, mark a point on the fly wheel w.r.t. to the fixed point indicating as IPO

5. When the piston just closes the inlet port completely, mark a point on the fly wheel w.r.t. to the fixed point indicating as IPC. Similarly opening and closing of the exhaust port and transfer port are marked on the fly wheel.

6. The port opening marks are measured from the nearest dead center and are converted into angle units and are tabulated

Fig. 9.1 Port timing diagram of 2 stroke petrol engine


Table 9.1 Measurement of port timing

S. No. Event TDC/BDC Before/After Timing indegrees

1TPO

2TPC

3EPO

4EPC

5IPO

6IPC

RESULT

Thus the port timing diagram of 2-stroke petrol engine is drawn.

VIVA QUESTIONS

1. What is meant by scavenging process?

2. What are the three ports that are present in two stroke engines?

3. How is lubrication provided in two stroke engines?

4. Why are two stroke engines not in much use?

5. What is meant by swirl?

6. How many revolutions of the crankshaft completes one full cycle in two stroke engines?

7. Tell any three differences between two stroke and four stroke engines?

8. Do we use two stroke diesel engines?

9. What are the problems with two stroke engines?


43

10. What is 2t oil?

REMARKS:


45


RETARDATION TEST ON A FOUR STROKE DIESEL ENGINE

AIM

To conduct retardation test on 4-stroke single cylinder diesel engine coupled with rope brake dynamometer.

APPARATUS & EQUIPMENT

4-stroke vertical single cylinder water cooled diesel engine coupled with rope brake dynamometer, tachometer.

ENGINE SPECIFICATIONS

Make: Kirlosker

Bore: 80mm

Stroke: 100mm

Speed: 1500rpm

Power: 5HP

Compression ratio: 16.5:1

PROCEDURE

This test involves the method of retarding the engine by cutting the fuel supply. The engine is made to run at no load and rated speed following all usual precautions. When the engine is running under steady operation conditions the supply of fuel is cut-off and simultaneously the time of fall in speed by 20%, 40%, 60%, 80% of rated speed is recorded and the test is repeated once again with 50% load on the engine. The values are tabulated in the table.

Table 10.1 Measurement of time at no load

S. No. Speed (rpm) Time (s) Drop in speed (rpm)


Table 10.2 Measurement of time at 50% load

S. No. Speed (rpm) Time (s) Drop in speed (rpm)

A graph with time for the falling speed (x-axis) and speed (y-axis) at no load as well as 50% load condition is drawn as shown. The time required to fall through the same range in both no load and load conditions are found. Let t2 and t3 be the time of fall at no load and load conditions respectively. The frictional torque and hence power are calculated as shown below.

FORMULAE

Maximum load conditions BP=2πNT/60,000 kWT=BP 60,000/2πNW R=BP 60,000/ (2πN 9.81) W= BP 60,000/ (2πNR 9.81) kgWhere BP=5HP=3.72 kWN=1500rpmR=0.19m

Full load torque T=BP 60,000/2πN kN-mHalf load torque =T/2 kN-mFrictional torque Tf =t3/ (t2-t3) T/2 kN-mFrictional Power (FP) = 2πNTf/60,000 kW


47

MODEL CALCULATIONS


FROM GRAPHt2= time for the fall of 100rpm at no load=

t3= time for the fall of 100rpm at full load=

Mechanical efficiency= BP 100/ (FP+BP) =

RESULT

Hence retardation test is conducted on 4-stroke single cylinder diesel engine coupled with rope brake dynamometer and its mechanical efficiency is determined.

VIVA QUESTIONS

1. Define the term mechanical efficiency

2. What is indicated power?

3. What is frictional power?

4. What is meant by William’s line?

5. What is torque?

6. Name any ten parts of the engine?

7. Define viscosity?

8. What is the instrument used for speed measurement?

9. What is injection pump?

10. How is diesel sprayed into the nozzle of cylinder?

REMARKS:


49



PERFORMANCE TEST ON MULTI CYLINDER

4 STROKE PETROL ENGINE (MORSE TEST)

AIM

To conduct performance test on the 4 stroke multi cylinder petrol engine and draw the performance curves.

APPARATUSStopwatch, Tachometer

ENGINE SPECIFICATIONS

Type: 4- cylinder 4-stroke petrol engine (water cooled) spark ignition.

Make: Hindustan Motors – ISZ.

Rated power output: 75 HP at 5000 rpm

Bore & Stroke: 84mm x 82mm

Compression ratio: 8.5:1

Clutch: Diaphragm type

Engine oil: SAE 20W /40 (4.5l capacity)

Loading: Hydraulic dynamometer

Starting: Auto start

THEORY

Performance test is conducted to check the performance claimed by engine manufacturer. Engine performance is an indication of the degree of success with which it is doing the assigned job i.e., conversion of the chemical energy contained in the fuel into the useful mechanical work. Brake thermal efficiency is important performance parameter. It is the ratio of energy in brake power to the supplied fuel energy. The power available at the output shaft end is called brake power.

Morse Test is used for multi-cylinder engines to measure input without the use of indicator diagram. It consists of running the engine with full load at rated rpm, which gives the brake power when all the cylinders are working. If the engine consists of four cylinders then the BP of the engine should be measured four times, cutting off power to spark plug of each cylinder turn by turn. By this a particular cylinder at each turn is made inoperative. If


one cylinder is inoperative then the power developed by that cylinder is lost and the speed of engine will fall as the load on the engine remains the same.

The engine speed can be restored to its original value by reducing the load on the engine by keeping the throttle position same. This is necessary to maintain FP constant because, it is assumed that the FP is independent of load and depends only on the speed of engine.

The observed difference in brake power between all the cylinders working and with one cylinder cut out is the indicated power of the cut out cylinder. Summation of indicated power of all the cylinders would give the total indicated power of the engine.

PROCEDURE

1) Check level of petrol in the petrol tank.2) Allow the cooling water to flow through the dynamometer.3) Allow petrol to flow and start the engine.4) Keep the loading in minimum position.5) The engine is set to the required speed by operating speed regulator.6) Apply load to the engine by operating loading hand wheel in anti-clockwise

direction in steps.7) Adjust the throttle to any desired speed.8) Cut- off the ignition to the spark plug of the first cylinder.9) Now the speed of the engine decreases, attain the normal speed by adjusting the

load without adjusting the throttle valve.10) Now note down all the readings speed, load, temperature, fuel flow, water flow, air

flow.11) Repeat the procedure (6) through (10) for different loads by cutting – off the other

cylinders, one at a time.12) Tabulate the readings.

Note: Temperature Points

T1 = Air inlet temperature

T2 = Engine cooling water inlet temperature

T3 = Engine cooling water outlet temperature

T4 = Exhaust gas temperature


51

FORMULAE

1) Brake Power (BP) =

N = Speed of engine in rpmW = Load in kgK = 2000, Dynamometer constant.

2) Total Fuel Consumption (TFC) = mf x 3600 kg/hr

mf = the mass of fuel consumed per second

mf kg/s

Density of petrol = 0.75 g/cc

t= time taken in seconds for consumption of 10 cc of petrol

3). Brake specific fuel consumption (BSFC)

g/kW-hr

4). Mechanical efficiency

5). Indicated thermal efficiency

Calorific value of petrol (CV) = 44,000kJ/kg

6). Brake thermal efficiency

7). Air fuel Ratio


A/f =mass of air/mass of fuel

Table 11.1 Measurement of Indicated power

Cylinder condition Engine speed N(rpm)

Load W (kg)

Brake power(kW)

Indicated power(kW)

All cylinders are firing (BP)= IP =

First Cylinder is cut-off(BP)1= (IP )1 =

Second cylinder is cut-off(BP)2 = (IP )2=

Third cylinder is cut-off(BP)3= (IP )3 =

Fourth cylinder is cut–off(BP)4= (IP )4 =

(IP) 1= (BP) – (BP) 1

(IP) 2 = (BP) – (BP) 2

(IP) 3 = (BP) – (BP) 3

(IP) 4 = (BP) – (BP) 4

IP = IP1 + IP2 + IP3 + IP4

FP = IP- BP

Note: 1) In Table 11.1, BP and IP are in ‘kW’ only

2) For every load calculate IP from table 11.2 and fill table 11.3

i.e. if experiment is conducted for 5 loads, there should be 5 tables.

Heat loss through exhaust gases = (ma+mf) Cpa (T4-T1)

ma = mass flow rate of air kg/s

mf = mass flow rate of fuel kg/s

Cpa = specific heat of air = 1.005 kJ/kg-K


53

T4 = exhaust gas temperature (K)

T1 = inlet air temperature (K)

Table 11.2 Measurement of temperature

S. No.

Engine speed N(rpm)

Load W

(kg)

Time for 10cc of fuel consumption

(s)

Air consumption

in mm of water read

on manometer

Cooling water flow

rate in (l/s)

Temperature points(C)

T1 T2 T3 T4

Unaccountable losses = Heat input - (Heat equivalent of BP+ Heat loss through cooling water+ Heat loss through exhaust gases)

Table 12.3 Heat balance sheet

Credit kJ/min % Debit kJ/min %

1)Heat Input

100 2)Heat equivalent of B.P

3)Heat loss through cooling water

4)Heat loss through exhaust gases

5)Unaccountable losses 100

Heat loss through cooling water = mw Cpw (Tw2 – Tw1)

mw = mass flow rate of cooling water kg/s

Cpw = specific heat of water = 4.18 kJ/kg-K

Tw2 =water outlet temperature

Tw1 =water inlet temperature


MODEL CALCULATIONS


55

GRAPHS

1. BP Vs Mech

2. BP Vs ITh

3. BP Vs BTh

RESULT

The performance test and Morse test on 4-stroke multi cylinder petrol engine is conducted and the performance curves are drawn.

VIVA QUESTIONS

1. Is Morse test conducted for single cylinder engine?

2. What are the different methods of finding out the frictional power of an engine?

3. Name the parts of 4 stroke petrol engine?

4. What is BSFC?

5. What is the difference between rich mixture and lean mixture?

6. What are the functions of a carburetor?

7. During cold starting problems, how do you start an engine?

8. What is the formula for calculating Break Power?

9. What is indicated power?

10. What are the units of power?


REMARKS:



57


PERFORMANCE TEST ON 4-STROKE DIESEL ENGINE

AIM To conduct the performance test on 4-stroke single cylinder diesel engine coupled with

rope brake dynamometer and to find out Brake power (BP) Indicated power (IP) Brake thermal efficiency Indicated thermal efficiency Mechanical efficiency

SPECIFICATIONSIt is a 4-stroke vertical single cylinder water cooled diesel engine coupled with rope

brake dynamometer.Make: KirloskerBore: 80mmStroke: 110mmSpeed: 1500rpmCompression ratio: 16.5:1Power: 5HP

APPARATUSStopwatch, Tachometer

PROCEDURE Calculate the rated load from specifications. Study the engine and know the starting procedure using decompression lever. Check the fuel level in the fuel tank and open the fuel knob. Check lubrication oil level in the crankcase Ensure cooling water supply to engine before starting the engine. Ensure cooling water supply to brake drum before loading the engine. Engine should be started on no load condition. Load should be added or removed gradually by adjusting the speed of the engine to its

rated value by screwing in or out of the governor nut. Engine should be stopped only at no load condition During starting the engine the handle used on the crank shaft to start the engine,

should be removed immediately once the engine is started Decompression lever should not be used to stop the engine. Do not over load the engine beyond ten percent more than the full load capacity

Table 12.1 Measurement of Speed


S. No. (W1-W2)

(kg)

Speed (N)

(rpm)

Time(s)

Table 12.2 Measurement of Indicated Power (IP)

S. No. BP

(kW)

Fuel consumption

(kg/s)

Frictional losses

(kW)

IP

(kW)

Input(mf xCV)

(kW)

BTth ITh Mech


59

MODEL CALCULATIONS

T=F RT= (W1-W2) 9.81 R=

mf =

Input energy= mf CV=

IP= BP+FP=

=

=

GRAPHS BP Vs Mech

BP Vs ITh

BP Vs BTh

RESULTThus the performance test on 4-stroke single cylinder diesel engine coupled with rope

brake dynamometer is conducted and the following are found.1. Brake power=2. Indicated power3. Mechanical efficiency4. Indicated thermal efficiency=5. Brake thermal efficiency=


VIVA QUESTIONS

1. What is the function of a dynamometer?

2. What is the function of clutch?

3. How are IC engines classified?

4. What is the difference between an IC engine and EC engine?

5. What is the valve timing diagram?

6. What is function of a fly wheel?

7. What are the functions of carburetor?

8. What is meant by volatility?

9. What is meant by calorific value?

10. What are the units of calorific value?

REMARKS:



61


HEAT BALANCE TEST ON FOUR STROKE DIESEL ENGINE

AIM

To conduct performance test on 4–stroke single cylinder diesel engine and draw a heat

balance sheet on kW basis.

SPECIFICATIONS

Engine Type : 4-stroke single cylinder diesel engine Make : Kirlosker Maximum Power(P ) : 5HP Rated Speed (N) : 1500 rpm Bore (D) : 80mm Stroke (L) : 110mm Starting : By hand crank Loading : Rope type dynamometer Cooling : Water cooling

DESCRIPTIONThe Test Rig consists of Four-stroke diesel engine (water cooled) to be tested for

performance and coupled to Rope type dynamometer. The arrangement is made for the following measurements of the set-up.

1) The Rate of Fuel Consumption is measured by using Volumetric Pipette. 2) Air Flow is measured by Manometer, connected to Air Box.3) The different loading is achieved by loading Rope type dynamometer.4) The engine speed is measured by electronic digital counter.5) Temperature at air inlet and engine exhaust gas are measured by

electronic digital temperature indicator with thermocouple.

OPERATION1) Check the diesel in the tank.2) Allow diesel and start the engine by using Hand crank.3) Keep the loading switches in off positions initially.4) Apply the load to the Rope type dynamometer with the help of spring

balances.5) Allow some time so that the speed stabilizes.6) Now take tachometer reading, temperature, and petrol flow rate and air

consumption.7) Repeat procedure (4) & (5) for different loads.8) Tabulate the readings as shown in the enclosed sheet.9) After the experiment is over, keep the petrol control valve closed.

Table 13.1 Heat balance sheet


Input

(kW)

% Output

(kW)

%

Heat supplied to the engine

100 Heat equivalent to brake power

Heat equivalent to friction power

Heat carried away by cooling water

Heat carried away by exhaust gas

Unaccounted heat loss

Total 100 Total

Table 13.2 Measurement of temperaturesS. No. Speed

(rpm)Load (kg)

Water manometer

reading

(mm)

Fuel Consumption

Temperature

(°C)

Atm. temp

(°C)

Calorimeter flow

rate(l/min)

Vol (cc)

Time (s)

T1 T2 T3 T4 T5


63

Note: temperature points

T1 = air inlet temperature T4 = water inlet to calorimeter

T2 = engine head water inlet temperature T5 =water outlet from calorimeter

T3 = engine head water outlet temperature T6 = exhaust gas inlet to calorimeter

S. No.

Load (kg)

BP (kW)

TFC

(kg/hr)

SFC

(kg/kW hr)

ma

(kg/min)

mf

(kg/min)

A/F (air fuel

Ratio )

Heat Input

(kW)

Brake Thermal

Efficiency η BTh

Mech. Efficiency

η Mech

T7 = exhaust gas outlet to calorimeter

Table 13.3 Measurement of fuel consumption

LIST OF FORMULAE

Input:

1. Heat input = mf CV kW

mf = mass of fuel consumption kg/s

CV = Calorific value 42000 kJ/kg

Output:

a) Brake power

B.P = kW

b) Heat lost by cooling water = mw CP w (T3 - T2) kW through engine head.

mw = mass flow rate of water kg/s

CPw = Specific heat of water = 4.2 kJ/kg-K

T3 = cooling water outlet temperature (K)

T2 = cooling water inlet temperature (K)

c) Heat lost by calorimeter water = mw CP w (T4 - T3) kW


T4 = cooling water outlet temperature (K)

T3 = calorimeter inlet temperature (K)

d) Heat lost by exhaust gases= (mf + ma) Cpa (T6 – T1) kW

mf = mass of fuel consumption

m a = mass of air used

CPa = Specific heat of air

T6 = temperature of outlet exhaust gas

T1 = temperature of air at inlet

e) Radiation and unaccounted heat loss = input - (a + b + c + d)

Mass flow rate of air

m a = ea Va

Va = Cd A

Cd = coefficient of orifice = 0.6

A = Area of orifice, d = 15 mm

ha =

a = density of air

Va = volume flow rate.


65

MODEL CALCULATIONS


GRAPHS1. TFC Vs BP2. η BTh Vs BP3. η Mech Vs BP4. SFC Vs BP

RESULT

Heat balance sheet for 4- stroke diesel engine is drawn at ¼th load.

VIVA QUESTIONS

1. What is a heat balance sheet?

2. What are the units of break specific fuel consumption?

3. What is thermal efficiency?

4. What is meant by swept volume?

5. What is clearance volume?

6. What is the formula for volumetric efficiency?

7. How does volume of cylinder affect the performance of engine?

8. What is the calorific value of petrol?

9. What is the calorific value of diesel?

10. What is meant by unaccounted heat loss?

REMARKS:

Signature of the faculty-In-charge



67

PERFORMANCE TEST ON TWO STROKE PETROL ENGINE

AIM

To perform a load test on the given engine and to draw the performance characteristic curves.

APPARATUS REQUIRED

2-stroke petrol engine test rig Stop-watch Tachometer

SPECIFICATIONS OF THE ENGINE

Engine Make: Bajaj

Rated Power: 4kW

Rated Speed: 3000 rpm

Volume: 100cc

Cooling Medium: Air cooled

Loading type: Rope brake dynamometer

Fuel properties:

Fuel: Petrol

Specific gravity of fuel = 0.78 g/cc

Calorific value = 44,000 kJ/kg

THEORY

A load test on an engine provides information regarding the performance characteristics of the engine. Engine performance varies with both loads on the engine as well as the engine speed. However stationary engines operate at a constant speed. The performance characteristics of such engines are obtained by varying the load on the engine.

EXPERIMENTAL SETUP

The compact and single engine test rig consisting of a two stroke, single cylinder, air cooled, and variable speed petrol engine coupled to a balanced brake drum by the flange coupling. The engine is kick-start type. A brake drum is mounted on a shaft with bearing blocks. Continuous water supply arrangement is provided to the brake drum for cooling. Rope braking arrangements with spring balances are provided for loading the engine. Screws rods are provided for easy loading. The whole arrangement is mounted on a sturdy iron


channel base plate. The control panel houses a water manometer, a multi-point digital temperature indicator and a digital rpm meter. A burette with a three-way cock is used for the fuel flow measurement. The fuel line is connected with a three way cock for the experimental needs such as

(i) To supply fuel from the fuel tank to the engine.

(ii) To fill fuel in the burette from the fuel tank.

(iii) To supply fuel from the burette to the engine.

STARTING THE ENGINE

1. Open the fuel supply2. Switch on the ignition key and kick the starting pedal.3. Throttle the engine to the rated speed and allow it to warm up

STOPPING THE ENGINE

Switch off the ignition key.

PROCEDURE

1) Start the engine at no load and allow idling for some time till the engine warm up.2) Note down the time taken for 10cc of fuel consumption using stopwatch and fuel

measuring burette.3) Open the fuel line to fill burette and supply fuel to run the engine from the fuel tank again.4) Load the engine gradually to the desired value.5) Allow the engine to run at this load for some time in order to reach steady state condition

and note down the time taken for 10 cc of fuel consumption.6) Repeat the experiment by applying additional loads to the desired values.7) Release the load gradually and stop the engine.8) Tabulate the readings as shown and calculate the result.

Table 14.1 Measurement of speed

S.No. Drum brake speed ( rpm)

Spring balance reading

(kg)

Fuel pipe reading

(s)

Air flow reading in

mm of water


69

Determination of maximum load (S-W)

FORMULAE

1. BP = kW

Where T= (S-W) R 9.81 N-mi. T = Torque

ii. S = spring balance readingiii. W= Loading weightiv. R = Brake drum radius

2. Specific fuel consumption = kg/kW-hr

3. From the graph drawn between brake power and total fuel consumption,The frictional power is found by the extrapolation methodFrictional horse power = kW

4. Indicated power = Brake power + Frictional power kW

5. ηMech= 100

6.


Table 14.2 Resultant tabulation

S. No.

Brake drum speed(rpm)

Fuel consume

dmf (kg/hr)

Air consumptio

n(kg/s)

Engine output(BP)(kW)

Specific fuel

consumption

(SFC)(kg/kW-hr)

Fuel(mf CV)

Air fuel ratio

η Mech

(%)η BTh

(%)

MODEL CALCULATIONS


71

PRECAUTIONS1. The engine should be checked for no load condition.2. The level of fuel in the fuel tank should be checked.3. The cooling water inlet for brake drum should be opened when loading.

GRAPHSBP Vs TFCBP Vs SFCBP Vs Mechanical efficiencyBP Vs Brake Thermal efficiency

RESULT


Load test on the given engine is performed and performance characteristic curves are drawn.

VIVA QUESTIONS

1. What is meant by crank case ventilation?

2. What is the purpose of piston rings?

3. What is the material used for piston and cylinder?

4. What is reboring of an engine?

5. What are the types of cooling systems used in IC engines?

6. What is nitriding of a crank shaft?

7. What is the purpose of carburetor?

8. What is meant by idling of an engine?

9. What is meant by cold starting?

10. What is turbulence?

REMARKS:


73

Signature of the faculty-In-charge

thermal & hydro lab expmnts

Documents

impact of vane

jet of water

area of jet

diameter of jet

flat vane aim

impact of jets

flat vane apparatus

vertical flat vane