Lab Manual PMFM

Laboratory Manual for

the course of

ME F341 PRIME MOVERS & FLUID MACHINES

BY

Department of Mechanical Engineering

Educational Development Division Birla Institute of Technology & Science, Pilani-

KK Birla Goa Campus, Zuarinagar, GOA- 403 726 2014-2015

CONTENTS

Table of Contents Page

No.

No. of Pull

Out Sheets

Description of laboratory ii-iii

General guidelines and safety measures iv

Guidelines for submission of lab. Reports v

Exp. 1.To study the characteristics of a Pelton turbine. 1-3 1

Exp. 2.To study the characteristics of a Francis turbine. 4-7 1

Exp. 3.To conduct a test on a single stage centrifugal pump at various speeds

to obtain the pump characteristics. 8-10 1

Exp. 4.To verify the fan laws using centrifugal pump 11-12 1

Exp. 5. To study the characteristics of a reciprocating pump at various head and

discharge to obtain the pump characteristics.13-15 1

Exp. 6.To study the performance of a hydraulic ram. 16-18 1

Exp. 7.To study the characteristics of a gear pump at constant speed. 19-21 1

Exp. 8.To conduct a performance test on a two-stage air compressor and

determine its volumetric efficiency and isothermal efficiency. 22-24 1

Exp. 9.To conduct performance test on a Greaves SCFS petrol engine running

at full throttle 25-29 1

Exp. 10. To conduct the performance test on a single cylinder four stroke

Diesel Engine running at constant speed and to prepare a heat balance

sheet.

30-37 1

Exp. 11. PC based performance analysis of Maruti Alto 3 cylinder, 4 stroke

MPFI petrol engine. 38-48 NA

Exp. 12. To plot pressure distribution on the profile of a Cylinder and the

profile of NACA 0018 airfoil, each placed in the laminar flow of air. 49-52 1

Exp. 13. To draw the valve timing diagram for the given cut-section model of a

diesel engine. 53-54 NA

Exp. 14. Study the constructional features of ic engines with the help of cut-

section model multi-cylinder petrol engine and diesel engine55-61 NA

DESCRIPTION OF LABORATORY

Prime movers and fluid machines laboratory is a hands-on investigation of performance

characteristics of various prime movers such as IC engines and the turbines as well as of

other fluid machines such as pumps and compressors. All these equipments normally

have to operate over a range of different operating parameters and the performance of

these equipments over a range assumes significant importance.

Objectives of the Laboratory component

x To supplement theory by enhancing the understanding of basic concepts of

mechanical power generation.

x To acquaint the student with various mechanical engineering equipments and

instrumentation and providing an opportunity to operate it.

x To provide the student an experience in engineering measurement,

experimentation and data interpretation.

x In addition, students get experience in technical communication in the form of

written laboratory reports

The brief focus of the experiments to be conducted in two laboratories is given below

Fluid Machines Laboratory

The laboratory has two hydraulic turbines, two positive displacement pumps, one

centrifugal pump, one hydraulic ram and a two stage reciprocating air compressor. In

almost all the fluid machines, the main characterictics that are important from practical

view point are mainly head under which it is operating (developing in case of a pump),

the discharge through it and the speed and the power developed (consumed in case of

pumps). In all the equipments, there are different means of measuring these important

parameters and a set of readings is taken to develop the graphs and the results may be

finally analysed.

ii

IC Engines Laboratory

The IC engines laboratory houses three different IC engines fitted with a different set

of instrumentation for measurement of operating parameters. An open circuit wind

tunnel is also installed, which may be used to generate laminar flow conditions for

various experiments.

Engine performance is more precisely defined by:

x The maximum power (or the maximum torque) available at each speed within the

useful engine operating range

x The range of speed and power over which engine operation is satisfactory

The following performance definitions are commonly used:

Maximum rated power: The highest power an engine is allowed to develop for short

periods of operation.

Normal rated power: The highest power an engine is allowed to develop in

continuous operation.

Rated speed: The crankshaft rotational speed at which rated power is developed.

To evaluate the performance of an engine the following are the most important

characteristics.

x Thermal efficiency

x Mechanical efficiency

x Indicated work per cycle

x Mean effective pressure

x Specific fuel consumption

x A/F & F/A ratio

x Volumetric efficiency

x Engine specific weight/volume

x Specific emissions

iii

GENERAL GUIDELINES AND SAFETY MEASURES

1. Wearing of an apron is compulsory. Dress worn by students should not have

loose clothes.

2. Students must be wearing proper shoes while working in the laboratory.

3. It is expected that before coming to the laboratory, the students has gone through

the instruction sheet for the experiment to be performed.

4. All data/readings must be recorded on the pull out sheets given at the end of this

manual.

5. The students should bring calculators and graph papers with them while coming

to the laboratory so that the results of the experiments may be verified.

6. Each group will be held responsible for loss or breakage of equipment checked

out to it.

7. Many of the experiments involve heavy equipment and machinery. Therefore, it

is very important that the safety measures and precautions must be thoroughly

read and adhered to before starting the equipment.

8. At the end of the experiment, ensure that all the valves in the equipment used are

closed and the electric supplies are switched off.

iv

GUIDELINES FOR SUBMISSION OF LAB. REPORTS

1. Report for each experiment will be due at the beginning of the next laboratory

class. Late submission will not be accepted.

2. Individual detailed lab report is to be submitted by each student for each

experiment.

3. Reports must be submitted on A4 size sheets only and must be suitably fixed in

the file.

4. A sample calculation for one of the readings taken has to be provided. If an

experiment is performed by a group, each group member must give the sample

calculation for a different reading.

Format for submission of Laboratory Reports

First page must bear the title of the experiment, the student details and the dates of

conduct of the experiment and submission of the report separately.

Left Hand Side Right Hand Side

(Pull out sheet) Aim of the experiment

Diagram Apparatus used

Data used Theory (in brief)

Sample calculation Procedure followed

Precautions

Discussion of results

v

1

EXPERIMENT NO. 1 AIM: TO STUDY THE CHARACTERISTICS OF A PELTON WHEELTURBINE

DIAGRAM

EQUIPMENT USED

Pelton Turbine, which is an impulse turbine works by using water available at high heads (pressure). All the available potential energy of water is converted into kinetic energy by a nozzle arrangement. The water leaves the nozzle as a jet and strikes the buckets of the Pelton wheel runner. These buckets are in the shape of double cups, joined at the middle portion in a knife edge. The jet strikes the knife edge of the buckets with least resistance and shock and glides along the path of the cup, deflecting through an angle of 160o to 170o. This deflection of water causes a change in momentum of the water jet and hence an impulsive force is supplied to the buckets. As a result, the runner attached to the buckets moves, rotating the shaft. The specific speed of the Pelton wheel varies from 10 to 100.

In the test rig the Pelton wheel is supplied with water under high pressure by a centrifugal pump. The water flows through a venturimeter to the Pelton wheel. A gate valve is used to control the flow rate to the turbine. The venturimeter with pressure gauges

PELTON TURBINE TEST RIG

Pelton Turbine

Sump

Venturimeter

P1P2

Spear mechanism

P

Pump

Turbine Casing

2

connected to it is used to determine the flow rate of water in the pipe. The nozzle opening can be decreased or increased by operating the spear wheel at the entrance side of turbine.

The turbine is loaded by applying dead weights on the brake drum. This is done by placing the weights on the weight hangar. The inlet head is read from the pressure gauge. The speed of the turbine is measured with a tachometer.

EXPERIMENTAL PROCEDURE

1. Close the delivery gate valve completely and start the pump. 2. Add minimum load to the weight hanger of the brake drum say 1kg. 3. Open the gate valve while monitoring the inlet pressure to the turbine. Set it for the

design value of 3.0 kg/cm2 4. Open the cooling water valve for cooling the brake drum. 5. Measure the turbine rpm with tachometer. 6. Note the pressure gauge reading at the turbine inlet. 7. Note the orificemeter pressure gauge readings, P1 and P2. 8. Add additional weights and repeat the experiments for other loads. 9. For constant speed tests, the main valve has to be adjusted to reduce or increase the inlet

head to the turbine for varying loads.

CALCULATIONS

I. To determine discharge: Venturimeter line pressure gauge readings = P1 kg/cm2

Venturimeter throat pressure gauge reading = P2 kg/cm2

Pressure difference, = 10(P1-P2) m of water

Venturimeter equation, Q =

Where, Cd - Venturimeter discharge coefficient - 0.96 ; A - inlet area = 2D /4pi Inlet diameter, D = 50mm; Throat diameter ratio, B = 0.6

31 2Q= 0.01024 (P -P ) m /s

2 1 2d 4

19.62 10(P -P )C AB (1-B )

3

II. To determine Head: Turbine Pressure gauge reading = P kg/cm2

Total Head , H = 10P m of water

III. Input to the turbine: Input = 9.81 QH (kW)

IV. Turbine Output: Brake drum diameter = 0.20 m Rope diameter = 0.015 m Equivalent drum diameter = 0.215 m Hanger weight - To = 1 kg Weight = T1 kg Spring Load = T2 kg Resultant load - T = (T1 - T2+ To) kg Speed of the turbine = N RPM

Turbine Output = 0.00011 NT kW

V. Turbine efficiency = Output / Input x 100PRECAUTIONS1. Always operate the turbine with a load. Since the runaway speed of the turbine is high,

running the turbine without any load will lead to excess vibrations and noise. 2. Provide cooling water for the brake drum when it is loaded. Absence of cooling water

will cause brake drum heating and even charring of the rope under extreme conditions. Amount of cooling water must be controlled to avoid excessive spillage and splashing.

3. The motor is provided with DOL starter to trip under overload, low voltage, uneven phase supply conditions. If the motor trips, check for voltage conditions. Also, do not run the supply pump at fully open valve conditions as this is an overload condition for the pump.

GRAPHS TO BE PLOTTED

Operating Characteristics: verses Unit Power Main Characteristics: verses Unit speed (N1); Unit Power verses Unit speed (N1)

9.8 DNT= kW

60000pi

4

EXPERIMENT NO. 2

AIM: TO STUDY THE CHARACTERISTICS OF A FRANCIS TURBINE.

DIAGRAM

EQUIPMENT USED

Francis turbine is a reaction type hydraulic turbine, used in dams and reservoirs of medium height to convert hydraulic energy into mechanical and electrical energy. Francis turbine is a radial inward flow reaction turbine. This has the advantage of centrifugal forces acting against the flow, thus reducing the tendency of the turbine to overspeed. Francis turbines are best suited for medium heads. The specific speed ranges from 25 to 300.

The turbine test rig consists of a 1.0 kW (1.34 HP) turbine supplied with water from a 5 HP centrifugal pump through suitable pipelines, a gate valve, and a flow measuring venturimeter. The turbine consists of a cast iron body with a volute casing and a gunmetal runner consisting of two shrouds with aerofoil shaped curved vanes in between. The runner is surrounded by a set of brass guide vanes. At the outlet, a draft tube is provided to increase the net head across the turbine. The runner is attached to the output shaft with a brake drum to absorb the energy produced.

Sump

Venturimeter

P1P2 P

Francis Turbine

FRANCIS TURBINE TEST RIG

Pump

V

Rope brake dynamometer

5

Water under pressure from pump enters through the guide vanes into the runner. While passing through the sprial casing and guide vanes, a portion of the pressure energy is converted into velocity energy. Water thus enters the runner at a high velocity and as it passes through the runner vanes, the remaining pressure energy is converted into kinetic energy. Due to the curvature of the vanes, the kinetic energy is transformed into the mechanical energy i.e., the water head is converted into mechanical energy and hence the runner rotates. The water from the runner is then discharged into the tailrace. The discharge through the runner can be regulated also by operating the guide vanes.

The flow through the pipe line into the turbine is measured with the venturimeter fitted in the pipe line. The venturimeter is provided with a set of pressure gauges. The net pressure difference across the turbine inlet and outlet is measured with a pressure gauge and a vacuum gauge. The turbine output torque is determined with a rope brake drum dynamometer. A tachometer is used to measure the rpm.


1. Add minimum load to the weight hanger of the brake drum 1kg. 2. Close the main gate valve and start the pump. 3. Open the gate valve while monitoring the inlet pressure to the turbine. Set it for the

design value of 1.0 kg/cm2. 4. Open the cooling water valve for cooling the brake drum. 5. Measure the turbine rpm with tachometer. 6. Note the pressure gauge and vacuum gauge readings at the turbine inlet and outlet. 7. Note the venturimeter pressure gauge readings, P1 and P2. 8. Add additional weights and repeat the experiments for other loads. 9. For constant speed tests, the main valve has to be adjusted to reduce or increase the inlet

head to the turbine for varying loads.

CALCULATIONS

I. To determine discharge: Venturimeter line pressure gauge reading = P1 kg/cm2

Venturimeter throat pressure gauge reading = P2 kg/cm2 Pressure difference, = 10 (P1-P2) m of water

6

Venturimeter equation is given as Q =

Where, venturimeter inlet dia D = 65mm ; throat dia ratio B = 0.6 Cd - venturimeter discharge coefficient = 0.98; A - inlet area = 2D /4pi

Q 31 2= 0.0174 (P -P ) m /sII. To determine inlet head of water: Turbine Pressure gauge reading = P kg/cm2

Turbine vacuum gauge reading = V mm of Hg Total Head H = 10(P+V/760) m of water

III. Input to the turbine: Input Power = 9.81 QH (kW)

IV. Turbine Output: Brake drum diameter = 0.20 m. Rope diameter = 0.015 m. Equivalent drum diameter = 0.215 m Hanger weight - To = 1 kg Weight = T1 kg Spring Load = T2 kg Resultant load - T = (T1 - T2+ To) kg Speed of the turbine = N RPM Output Power =

= 0.00011 NT kW V. Turbine efficiency = (Output Power/Input Power)x100 %

PRECAUTIONS4. Always operate the turbine with a load. Since the runaway speed of the turbine is over

4000 rpm, running the turbine without any load will lead to excessive vibrations and noise.

5. Provide cooling water for the brake drum when it is loaded. Absence of cooling water will cause brake drum heating and even charring of the rope under extreme conditions. Amount of cooling water must be controlled to avoid excessive spillage and splashing.

3.14 DNT= kW

6120

2 1 2d 4

19.62 10 (P -P )C AB (1-B )

7

6. The motor is provided with DOL starter to trip under overload, low voltage and uneven phase supply. If the motor trips, check for voltage conditions. Also, do not run the supply pump at fully open valve conditions as this is an overload condition for the pump.

GRAPHS TO BE PLOTTED Operating Characteristics: verses Unit Power Main Characteristics: verses Unit speed (N1); Unit Power verses Unit speed (N1)

8

EXPERIMENT NO. 3 AIM: TO CONDUCT A TEST ON A SINGLE STAGE CENTRIFUGAL

PUMP AT VARIOUS SPEEDS TO OBTAIN THE PUMP CHARACTERISTICS.

DIAGRAM

EQUIPMENT USED

A Centrifugal Pump consists of an impeller rotating inside a casing. The impeller has a number of curved vanes. Due to the centrifugal force developed by the rotation of the impeller, water entering at the center flows outwards to the periphery. Here it is collected in a gradually increasing passage in the casing known as a volute chamber. This chamber converts a part of the velocity head (kinetic energy) of the water into pressure head (potential energy). For higher heads, multistage centrifugal pumps having two or more impellers in series will have to be used.

Collecting tank

Scale

CENTRIFUGAL PUMP TEST RIG

Centrifugal Pump

V P Motor

Energy meter

Sump

9

The test pump is a single stage centrifugal pump coupled to a 1 HP capacity single phase AC motor by means of a cone pulley belt drive system. An energymeter and a stop watch are provided to measure the input to the motor and a collecting tank to measure the actual discharge. A pressure gauge and a vaccuum gauge are fitted in the delivery and suction pipe lines to measure the pressure.


1. Loosen the V-belt by rotating the handwheel of the motor bed and position the V-belt in the required groove of the pulley. 2. Prime the pump with water if required. 3. Close the delivery gate valve completely. 4. Start the motor and adjust the gate valve to required pressure and delivery. 5. Note the following readings (a) The Pressure gauge reading, P kg/cm2 (b) The vaccuum gauge reading, V mm of Hg (c) Time for 10 revolutions of energymeter disc, T secs (d) Time for 10 cm rise in the collecting tank , t secs (e) Pump speed in RPM Take 3 or 4 sets of readings by varying the head from a maximum at shut off to a minimum where gate valve is fully open. The experiment is repeated for other pump speeds.

OBSERVATIONS (a)The Pressure gauge reading, P (kg/cm) (b) The vacuum gauge reading, V (mm of Hg) (c) Time for 10 revolutions of energymeter disc, T(s) (d) Time for 10 cm rise in the collecting tank, t (s) (e) Pump speed, N (RPM)

CALCULATIONS

1. Discharge: Area of tank, A = 0.5x 0.5 m2

Rise of level, = h m Volume collected = A h m3 Time taken for a 10 cm rise = t (s)

10

Discharge, Q = Volume/Time 2. Head: Total Head, H =10 [P + V/760] m of water

3. Output of the pump: Output = 9.81 Q H (kW)

4. Input of the Motor: Energymeter constant, n = 1200 revs per kWh. Time for 10 revolution = T (s) Assuming motor and transmission efficiencies as 80% and 90% respectively. Pump input

5. Pump efficiency = Pump output/Pump input

PRECAUTIONS

1 Always keep the delivery valve closed before starting the pump. 2 Take care that the does not run dry. 3. Important: Since the centrifugal pump is not self priming, the pump must be filled with water (priming) before starting. For this reason, water should not be allowed to drain and a foot valve is provided.

GRAPHS TO BE PLOTTED H verses Q verses Q verses H

3600 10 0.8 0.9=

1200 T21.6

= kWT

11

EXPERIMENT NO. 4 AIM: TO VERIFY FAN LAWS USING CENTRIFUGAL PUMP. Theory: For any turbo-machinery, the variables of Discharge, Head and Power are related to the speed through various relations as given below and these relations are called fan laws.

First Fan Law: For a given machine, the discharge is directly proportional to speed of the machine (pump/turbine/compressor etc.) Q NThis law can be theoretically verified from dimensionless number of Discharge coefficient which is given as below.

3QQC

ND=

As CQ and D are constants for a given machine, so discharge (Q) is directly proportional to speed (N).

Second Fan Law: For a given machine, the head is directly proportional to the square of the speed of the machine (pump/turbine/compressor etc.)

2H NThis law can be theoretically verified from dimensionless number of Head coefficient which is given as below.

2 2HgHC

N D=

As CH, D and g are constants for a given machine, so head (H) is directly proportional to speed squared (N2). Third Fan Law: For a given machine, the power is directly proportional to the cube of the speed of the machine (pump/turbine/compressor etc.)

3P NThis law can be theoretically verified from dimensionless number of Power coefficient which is given as below.

3 2 2 3 3 5( )PP P PC

gHND g N D ND gN D = = =

As CP, D, and g are constants for a given machine, so power (P) is directly proportional to cube of speed (N3).

Verifications: For first Fan law Verify that the ratio (Q/N) will be almost constant. Also draw a graph between Q and N and verify that it is almost a straight line.

12

For Second Fan Law Verify that the ratio (H/N2) will be almost constant. Also draw a graph between H and N2and verify that it is almost a straight line.

For Third Fan Law Verification: Verify that the ratio (P/N3) will be almost constant. Also draw a graph between P and N3 and verify that it is almost a straight line.

13

EXPERIMENT NO. 5

AIM : TO STUDY THE CHARACTERISTICS OF A RECIPROCATING PUMP AT VARIOUS HEAD AND DISCHARGE TO OBTAIN THE PUMP CHARACTERISTICS.

DIAGRAM

EQUIPMENT USED

The Reciprocating pump is a positive displacement type pump and consists of a piston or a plunger working inside a cylinder. The cylinder has two valves, one allowing water into the cylinder from the suction pipe and the other discharging water from the cylinder into the delivery pipe. Specification of the pump:

Type: Double acting single cylinder (a) Piston Stroke L = 44.5 mm (b) Piston Diameter d = 38 mm (c) Suction pipe diameter = 25 mm (d) Delivery pipe diameter = 18 mm

Collecting tank

Scale

RECIPROCATING PUMP TEST RIG

Reciprocating Pump

V P Motor

Energy meter

Sump

14

An energymeter and a stopwatch are provided to measure the input to the motor and a collecting tank to measure the actual discharge. The pump is driven by the Motor. A set of pressure gauge and vacuum gauges are provided along with the required pipe lines.

EXPERIMENTAL PROCEDURE 1. Select the required speed. 2. Open the gate valve in the delivery pipe fully. 3. Start the motor. 4. Throttle the gate valve to get the required head delivery pressure. 5. Note the following readings (a) The Pressure gauge reading, P kg/cm2 (b) The vacuum gauge reading, V mm of Hg (c) Time for 10 revolutions of energymeter disc, T (s) (d) Time for 10 cm rise in the collecting tank, t (s) 6. Take atleast 3 - 4 sets of readings by varying the head. CALCULATIONS

1. Discharge: Area of tank, A = 0.16 m2

Rise of level, R = 0.1 m Volume collected, AR = 0.016 m3 Time taken = t secs Discharge, Q = Volume/Time = 0.016/t m3/sec 2. Head: Total Head, H = 10(P + V/760) m of water

3. Output of the pump: Pump output = (9.81 QH) kW

4. Input of the Pump: Energymeter constant, N = 750 revs/kW Hr Time for 10 revolution = T secs. Assuming the efficiency of motor as 80%

15

5. Efficiency of the Pump:

Pump efficiency = Pump output/Pump input

PRECAUTION: Never close the gate valve completely.


0.8 3600 10Pump input = 750 T

38.4 = kW

T

16

EXPERIMENT NO. 6

AIM: TO STUDY THE PERFORMANCE OF A HYDRAULIC RAM.

DIAGRAM

EQUIPMENT USED

Hydraulic Ram is a simple device working on the water hammer principle, which enables the dynamic pressure of a large quantity of water flowing under a low head to lift a small portion of water to a higher head. It consists of a supply pipe connected at its upper end to the reservoir and at its lower end to the ram inlet. At the ram outlet, the waste water flows out in the large opening and a small quantity of water at high pressure flows through the smaller delivery valve.

HYDRAULIC RAM TEST RIG

Flow regulating valve

Pressure Gauge

Waste water valve

Air vessel

Supply tank

Useful water at high head

Scale

Sump

0.6m

2.0m 0.8m

17


The ram will require some back pressure to begin working Priming process. 1. Admit water into supply tank. 2. Initially the ram will have to be manually started several times to remove all the air.

Open the valve in the long inlet pipe to ram after water has reached a certain level in the supply tank.

3. Open the ram outlet valve slightly to allow water and any air in the system to flow out.

4. When the water from the supply tank flows out through the waste water valve, the swing check inside this valve shuts. Manually push it open again use a rod to push this as the swing check is inside the valve. This process of pushing the swing check may have to be repeated several times until all the air is purged from the system and pressure builds up in the ram.

5. Adjust the ram outlet valve to obtain the required water outlet pressure - delivery pressure gauge reads about 1kg/sq.cm about 10m of water.

6. Keep the supply head constant by controlling suitably the inflow into the supply reservoir - say 50-70 cm in the tank gauge glass scale.

7. Measure the total discharge in passing through ram by closing the inlet valve to the supply tank and the time taken for the water level in the tank to fall a few cms (5cms or 10cms). Wastewater WW can be calculated by subtracting the useful water from this total discharge.

8. Note the useful water pumped per minute from the collecting tank at the high pressure. This discharge is useful water WU.

CALCULATIONS Supply tank cross-section = 0.5 m 0.5 mSupply head = (2.6-0.8) =1.8 m of water Delivery tank cross-section = 0.3 m 0.3 mDelivery head = 10P m of water Supply side water consumption rate,

Useful water rate, 3

U0.3 0.3 water rise in collecting tank (in m)W =

time for water risem

s

3S

0.5 0.5 water level fall in supply tank (in m)W =time for water level fall

ms

18

Supply head (in meters of water), HS = height of water surface in the supply tank above waste water valve Delivery head (in meters of water), Hd = pressure gauge reading (in meters of water). There are two different definitions of efficiency used for a hydraulic ram

PRECAUTIONS 1. During the start up operation i.e. while opening the waste valve, only adequate force

must be applied to to push the valve open. 2. The water level in the supply tank should be maintained in a small range to get

accurate results. 3. The flow regulating valve should be opened slowly and the readings must be taken

when the pressure gauge on the air vessel shows a steady state reading.GRAPHS TO BE PLOTTED Rankine verses Hd/Hs Rankine verses WU D Aubisson verses Hd/Hs

U d

S S

W H(a) D 'Abuissons' Efficiency = W H

U d S

S S

W (H H )(b) Rankine Efficiency = W H

19

EXPERIMENT NO. 7 AIM: TO STUDY THE CHARACTERISTICS OF A GEAR PUMP AT CONSTANT SPEED.

DIAGRAM

EQUIPMENT USED

The gear pump is a positive displacement type of pump and consists of a pair of helical of spur gears meshed with each other and housed closely in a casing. One gear is fitted with an external shaft that is coupled to an AC motor (1440 RPM). In the oval shaped pump casing, the two involute curved double helical gear wheels are mounted on shafts. These gears lock during rotation in the suction chamber and as they rotate, the liquid between the pump casing and the space between the teeth is transferred to the delivery chamber.

The test pump is coupled to a 1 HP AC motor (220 Volts, single phase). A suitable switch is provided. The pump sucks oil from a reservoir and delivers to a collecting tank, that is provided with an overflow arrangement. The collected oil is transferred back to the

Collecting tank

Scale

GEAR PUMP TEST RIG

Gear Pump

V P Energy meter

Motor

Sump

20

reservoir through a ball valve. Suitable pressure and vacuum gauges are fitted in the pipe lines, to measure suction and delivery head. A modified gate valve is fitted in the delivery side that prevents complete shut off. An energymter with a stop watch is provided to measure the input power.

EXPERIMENTAL PROCDURE

1. Fill the supply tank with oil to the required height, say, three fourth of the tank. 2. Open the gate valve in the delivery pipe fully.3. Start the motor. Oil flows in. 4. Throttle the gate valve to get the required head. 5. Note the following readings (a) Pressure gauge and vaccuum gauge readings (b) Time for 10 revolutions of energymeter disc, T secs (c) Time for 10cm rise in collecting tank, t secs Take 4 to 5 sets of readings by varying the delivery pressure.

CALCULATIONS

I. Discharge: Time for 10cm. rise = t (s) Area of collecting tank , A = 0.3 x 0.3 m2

Rise in oil level, h = 0.1m Discharge , Q = Ah/t m3/s. = 0.09/ t

II. Total delivery head: Pressure = P kg/cm2

Vaccuum = V mm of Hg

Total Head, H = m of oil

Specific Gravity, SG = 0.83 (for high speed diesel)

III. Output of the pump: Output = 9.81(SG)QH (kW)

oil

VP+ 10760SG

21

IV. Input to the pump: Energymeter constant = 900 revolutions/kWh. Time for 10 revolutions = T (s) Input to the pump

=32/T kW Where, 0.8 is the motor efficiency

V. Efficiency: Pump efficiency = (Output/Input) x 100%

PRECAUTION 1. While the pump is running, the delivery valve should not be closed completely for

prolonged periods


3600 10 0.8= kW

900T

22

EXPERIMENT NO. 8

AIM: TO CONDUCT A PERFORMANCE TEST ON A TWO-STAGE AIR COMPRESSOR AND DETERMINE ITS VOLUMETRIC EFFICIENCY AND ISOTHERMAL EFFICIENCY.

DIAGRAM

EQUIPMENT USED

The air compressor used is a two stage, reciprocating type air compressor. The air is sucked from atmosphere and compressed in the first cylinder. The compressed air then passes through an inter cooler into the second stage cylinder, where it is further compressed. The compressed air then goes to a reservoir through a safety valve. This valve operates an electrical switch that shuts off the motor when the pressure exceeds the set limit. The test unit consists of an air chamber containing an orifice plate and a U-tube manometer, the compressor and an induction motor.

High Pressure Storage Vessel

Manometer

AIR COMPRESSOR TEST RIG

Air Compressor

Energy meter

Motor

Air Box Pressure regulating valve

23

Compressor Specification: Dia of low pressure piston = 80 mm Dia of High Pressure Piston = 50 mm Stroke = 90 mm


1. Close the outlet valve. 2. Fill up the manometer with water upto the half level. 3. Start the compressor and observe the pressure developing slowly. 4. At the particular test pressure, the outlet valve is opened slowly and adjusted so that the

pressure in the tank is maintained constant. 5. Observe the following readings: i. Time taken for 10 revolutions of energymeter disc ii. Speed of the Compressor, N (R.P.M.) iii. Manometer readings h1 and h2 (cm of water). vi. Pressure gauge reading, P (kg./cm2).

CALCULATIONS

Volumetric Efficiency Water head causing flow, h = (h1 - h2) cm of water Air head causing flow, H =

Where w = Density of water = 1000 kg/m3

a = Density of air = 1.162 kg/m3 (at 30 oC)

Actual volume of air compressed, Va = 3dC A 2gH m /sec

Where, Cd = Coefficient of discharge of orifice = 0.62 A = Orifice area = 0.000314 m2 ( dia - 20mm) g = 9.81 m/s2

3a V = 0.0008623 H m /s

w

a

h m of air

100

24

Theoretical volume of air, Vt

Where, D = Diameter of Piston = 0.08 L = Stroke length = 0.09m N= RPM of the compressor.

Volumetric efficiency = (Va/Vt)x100%

Isothermal Efficiency

PRECAUTIONS

1. Check oil level in the compressor crank case. 2. The orifice should never be closed, lest the manometer liquid (water) will be sucked into the tank. 3. At the end of the experiment the outlet valve at the air reservoir should be opened as the compressor is to be started again at low pressure to prevent undue strain on the piston. GRAPHS TO BE PLOTTED Vol verses PDelivery Iso verses PDelivery

23D LN

m /s4 60

pi=

Energymeter constant, n = 200 revolutions/kWhTime for 10 Rev = T (s) Assuming the efficiency of motor and Belt transmission as 80% and 95%

(3600 10 0.8 0.95)Actual Compressor Input, compressor input = ( 200 t)136.8

= kWt

Isothermal

atm a

g atm atm

a tm aiso

or ideal input=P V ln(C) [Pressure in kPa] where, Compression Ratio (C) =(P +P )/P

P V ln(C) Isothermal Efficiency, = (136.8/t)

25

EXPERIMENT NO. 9

AIM: TO CONDUCT PERFORMANCE TEST ON A GREAVES SCFS PETROL ENGINE RUNNING AT FULL THROTTLE.

DIAGRAM

Engine

Air box Air Inlet

Hydraulic dynamometer

Magnetic proximity speed sensor

Exhaust

Cooling Water

Calorimeter

Fuel measuring unit

Fuel Inlet

Orifice meter

Fins for air cooling

26

EQUIPMENT USED 1. Engine

The engine is Single Cylinder Four Stroke Petrol Engine

Model MK 12/2 Make Greaves Cooling Air-cooled

Power 3 HP Bore 0.055 m Stroke - 0.050 m

Calorific value of fuel used (Cv) = 42000 kJ/kg o C Specific gravity of fuel = 0.85 kg/l

2. Instrumentation for measuring various inputs/outputs

All instrumentation is incorporated on a control panel. The various factors to be

measured as follows,

(a) Fuel measurement This is done by using pipette and a stopwatch. The pipette is made up of

toughened glass. It is used to measure fuel consumption. The amount of fuel

consumption is determined by measuring the time required for the consumption of

Petrol volume in the pipette at each stage of the loading. When valve is open fuel

supply is fed to engine from fuel tank, when valve is closed fuel supply is fed to

engine from pipette.

(b) Air Flow measurement Air flow is measured using an air box, orifice and manometer arrangement.

The inlet of the air suction box consists of orifice housed in the orifice flanges.

Pressure difference across the orifice is read on the manometer. The outlet of

the air suction box goes to the engine through a flexible hose for air suction.

(d) Speed Measurement The speed of the Engine is measured by a tachometer and it is displayed on the

Control Panel. The speed displayed is in RPM (Revolutions per Minute).Alternately, speed can be measured by a non contact tachometer provided.

27

3. The hydraulic dynamometer

A hydraulic dynamometer consists of a rotating disc in a casing filled with water.

The power output from the engine is absorbed by water vortices generated in the

pockets between rotor and stator vanes as shown in the diagram. The resulting

drag applies a moment to the dynamometer housing which is measured by a

spring balance mounted at a fixed distance from the centerline of the

dynamometer. Absorbed power varies with rotational speed and with the mass of

water contained in the rotor chamber. With a fully filled rotor chamber, power

varies with the cube of speed. Power is modulated with the water inlet control

valve. A continuous flow of water through the dynamometer is required to provide

resistance to rotation and to remove the heat generated by the power absorption

process. Depending solely on absorbed power and allowable temperature rise,

typical water flow requirements is around 20 l/hr kW.

PROCEDURE

1. Ensure that sufficient fuel is present in the fuel tank.

2. Take fuel cock in Start position

3. Ensure that sufficient water flow is ready to be circulated to the dynamometer.

4. Ensure that the engine is not loaded.

5. Wrap the knotted end of the rope around the starting pulley in the clock-wise direction

and hold the knob portion of the rope. Pull slowly till the compression and give a brisk

pull to start the engine.

6. If required, give Choke. If choke is On, put it Off after the engine starts.

7 Let the engine stabilize.

8 Take the readings as per observation table under no load conditions.

9 With the help of load scale, adjusting the water supply to the dynamometer and rotating the loading wheel of the dynamometer, gradually load the engine in steps.

10 Let the engine stabilize for each load value.

11 Take the readings as per observation table.

12 Repeat steps 9, 10 & 11 for different load.

28

13 Gradually unload the engine by gradually reducing the wtare supply to the dynamometer.

Do not take the readings while unloading.

14 To stop the engine take the fuel cock in Stop position.

15 Obtain the important curves describing the characteristics of the engine.

OBSERVATIONS AND CALCULATIONS: Brake Power

If the Engine speed is N rpm and W is the load in kg

For given hydraulic dynamometer

Brake Power, 0.7362000

WNBP kW=

Total Fuel Consumption If t is time for the consumption of entire fuel in pipette (sec) and the pipette volume is 15 ml

Brake Specific Fuel consumption

Total Heat I/P rate

42000VTFC C TFC= = (kW)

TFCBSFC kg/s/kW BP

=

29

Brake Thermal Efficiency

Volumetric Efficiency

where

Diameter of orifice, d = 11.78mm = 0.01178 m

Area of the cross-section of the orifice = A= 0.000109m2

Coefficient of discharge of orifice , Cd= 0.60

Theoretical consumption of air 2 2

33.14 (0.055) (0.05) 0.000000989 ( / )2 4 60 2 4 60

100 %

Th

ActVolumetric

Th

D LN NQ N m s

QQ

pi

= = =

=

RESULTS AND CONCLUSIONS Plot the following graphs

1. Specific Fuel Consumption Vs Engine Speed

2. Brake thermal efficiency. Vs Engine Speed

3. Volumetric efficiency Vs Engine Speed

PRECAUTIONS:

Avoid shutting off the engine under loaded condition.

Never wrap the rope around your hand while starting the engine.

Take away the rope from pulley once the engine starts.

Never stop the engine by pulling the spark plug cap.

Brake Thermal

v

BP 100 %

C TFC =

( )act d

3

Actual Volume of air (measured by air box& orifice), Q C A 2 gh = 0.0002895 h m / s

=

1 2H -H 1000Height of equivalent air column, h 1000 1.178

=

30

EXPERIMENT NO. 10 AIM: TO CONDUCT THE PERFORMANCE TEST ON A SINGLE

CYLINDER FOUR STROKE DIESEL ENGINE RUNNING AT CONSTANT SPEED AND TO MAKE ITS HEAT BALANCE SHEET.

DIAGRAM

EQUIPMENT USED 1. Engine

Type: Single Cylinder Four Stroke Diesel engine.

RPM: 1500 Power: 5 kW Fuel: Diesel

Lubricant Oil: SAE40 Bore: 80mm Stroke: 110 mm

Engine

Air box Air Inlet

Cooling Water

T5 T6

Band brake dynamometer

Magnetic proximity speed sensor

Exhaust

T3 T4

T1 T2

Cooling Water

Calorimeter

Fuel measuring unit

Fuel Inlet

Orifice meter

31

2. Band Brake Dynamometer A Band Brake Dynamometer is provided to load the engine with different torque

values.

3. Instrumentation for measuring various inputs/outputs

The various factors to be measured as follows: (a) Fuel measurement

This is done by using pipette. This instrument is placed on a panel. The fuel

tank is mounted on a panel. Fuel is supplied to the engine using a fuel line. Observe

the time required for 15ml amount of fuel consumption with the help of stopwatch. A

valve is used to fill the pipette and to allow the fuel to flow to the engine.

(b) Exhaust gas heat loss measurement Exhaust gases from the engine passes through the flexible hose to the

calorimeter. The calorimeter is mounted on a stand and supports. Exhaust gas enters

into the calorimeter through the calorimeter exhaust gas inlet. Heat is exchanged by

circulating water through a copper pipe in the calorimeter. Sensors mounted at various

positions measure the temperatures at that point.

(c) Temperature measurement The temperature at of different points is measured and displayed on

temperature indicator on control panel. The points are,

T1 = Temperature of exhaust gas inlet to Calorimeter in 0C

T2 = Temperature of exhaust gas outlet from Calorimeter in 0C

T3 = Temperature of water inlet to Calorimeter in 0C

T4 = Temperature of water outlet from Calorimeter in 0C

T5 = Temperature of water inlet to Engine in 0C

T6 = Temperature of water outlet from Engine in 0C

(d) Speed Measurement The speed of the Engine is measured by magnetic proximity based

tachometer and it is displayed on the Control Panel. The speed displayed is in RPM

(Revolutions per Minute).

32

(e) Load Measurement Spring balance is used to measure the load on the dynamometer.

(f) Air Flow measurementAirflow is measured using an air box, orifice and manometer arrangement.

The inlet of the air suction box consists of orifice housed in the orifice flanges.

Pressure difference across the orifice is read on the manometer. The outlet of the air

suction box goes to the engine through a flexible hose for air suction.

THEORY

The energy balance of an internal combustion engine:

The distribution of energy in an internal combustion engine is best considered in

terms of the steady flow energy equation, combined with the concept of the control volume.

For considering total energy balance, energy entering & going out of the system has to be

taken into account in:

fuel, with its associated heat of combustion

air, consumed by the engine

power developed by the engine

exhaust gas

heat to cooling water or air

convection and radiation losses to the surroundings

The steady flow energy equation gives the relationship between these quantities, and is usually expressed in kilowatts:

H1 = Ps + (H2 - H3) + Q1 + Q2

Where

H1 = combustion energy of fuel

Ps = power output of engine

33

H2 = enthalpy of exhaust gas

H3 = enthalpy of inlet air

Q1 = heat to cooling water Q2 = convection and radiation

PROCEDURE

Before actually starting the engine, make following settings.

1. Switch ON the Mains power supply to the control panel.

2. Fill diesel in the fuel tank. Put ON the valve V1 mounted on the fuel consumption-

measuring unit, to fill the fuel in the pipette.

3. Start the water supply for engine cooling and calorimeter cooling. Ensure that the water

flow rate and pressure of the water supply is as required.

4. Start the engine by cranking the shaft using the handle provided. Use decompressor lever

of the engine to crank the engine. Make sure that the engine is under no load condition.

Please follow the following procedure to start the engine.

a. Lift the decompressor lever. Use the handle provided along with Engine to

crank the engine.

b. Rotate the Engine shaft with the handle and turn the flywheel fast. When the

flywheel attains a good speed, push the decompressor lever down. The engine

will fire. Remove the handle immediately.

5. Give the water supply to the brake drum to avoid excessive heating of the band of the

loading arrangement.

6. Load the engine with the help of hand-wheel provided on the loading arrangement. Load

the engine gradually by rotating the hand-wheel clockwise. Load value is indicated on the

load indicator on the load scale.

34

7. Do not load/unload the engine to its maximum capacity suddenly. Increase the load

gradually.

8. Let the engine stabilize.

9. Take the readings as per observation table.

10. Gradually increase the load and let the engine stablise again

11. Repeat steps 8, 9 & 10 for different load.

12. Unload the engine gradually by rotating the hand-wheel anticlockwise till the load scale

show the zero reading before stopping the engine.

13. Do not take the readings while unloading.

14. After completely unloading the engine press the stop lever provided on the fuel pump and

hold it in that position till the engine comes to stands till off.

OBSERVATIONS AND CALCULATIONS Brake Power

1 22 ( ) 0.000157 ( )60000

NR S SBP WN kWpi = =

Where, N is the engine speed in RPM, W is the load in kg and is equal to

difference between spring balance readings, S1 and S2.

Total Fuel Consumption If (t) is time for the consumption of entire fuel in pipette (sec) and the pipette volume is 15 ml

100015 0.831 0.012465 /

1000

fuelpipette volumeTFCt

TFC kg st t

=

= =

35

Brake Specific Fuel Consumption, bsfc BSFC = TFC/BP (kg/s/kW)

Friction Power

The value can be obtained by extrapolation of TFC Vs BP graph (Willans Line). The intercept on BP axis gives the amount of power spent against friction in kW.

Indicated Power

Indicated Power, Id P =BP +FP (kW)

Total Heat Input

Heat carried away by engine cooling water

Where, mw2= Cooling water flow rate of Engine (kg/sec) Air Intake

Where

Diameter of orifice, d = 0.022 m

water

2 1water

1 2

1000Air head, h H 1.178

H -Hand H =

100where H and H are manometer readings in cm

=

in VTotal Heat Input, H TFC C 44000 kWTFC= =

(kJ/sec)H water coolingEngineby Away CarriedHeat w=

w W2 p 6 5H (kJ/sec) C (T - T )m=

( )( )

3act d

3

Actual volume of air (measured by air box& orifice), Q C A 2 gh m / =0.0010097 h m /

s

s

=

36

Coefficient of discharge of orifice, Cd= 0.60

Heat Carried Away By Exhaust Gas If cooling water flow rate through calorimeter = mw1 (kg/sec)

Alternately

Unaccounted Heat Loss

%Unaccounted Heat Loss,

%100% xH

HH

in

unacc

unacc =

PRECAUTIONS1. Check the cooling system of the engine. Do not run engine when there is no or improper

water supply for engine cooling.

( )Unaccounted Heat Loss Heat input - (Heat Converted to BP Heat Carried by Exhaust

Heat Carried by Engine Cooling Water)

=

+ +

exh

ambiant1w1 4 3

1 2

Heat carried away by the exhaust gases, H T - T

4.18 (T - T ) (kJ/sec)T - T

m=

exh

act p 1 ambient

Heat carried away by the exhaust gases, H Q C (T - T ) (kJ/s)air=

37

2. Do not run engine without sufficient lubrication oil. Oil sump must have sufficient oil up

to the level. Fill up if necessary up to the level marked on the oil level indicator. Use

SAE30/SAE40 oil for engine.

3. Do not let engine speed exceed 1600 rpm under any condition. Normal operation should

be 1500 rpm. Do not let the exhaust temperature exceed 5000C.

4. While starting the engine, hold the lever until the engine starts and pull out

immediately after the engine has started. Otherwise, the engine may start in the reverse direction and may lead to serious accidents.

5. Washing the engine with water is not advisable.

6. If you are not using the engine for long time, drain the fuel tank and all fuel pipes. Drain

water from the water tank.

7. Ensure that the engine is not loaded when starting.

8. After starting the engine gradually increase the load.

9. DO NOT USE DECOMPRESSOR LEVER TO STOP ENGINE. DECOMPRESSOR LEVER IS USED ONLY TO START THE ENGINE AND NOT TO STOP THE ENGINE.


Brake Th verses BP TFC verses BP BSFC verses BP Heat balance graph

38

EXPERIMENT NO. 11 AIM: PC BASED PERFORMANCE ANALYSIS OF MARUTI ALTO 3

CYLINDER, 4 STROKE PETROL ENGINE. DIAGRAM

EQUIPMENT USED

Engine Maximum Output :- 47 PS @ 6200 rpm

Maximum Torque :- 62 Nm @ 3000 rpm

Engine Capacity :- 796CC

Engine Anemometer

Air InletTambient

Cooling Water

Flow meter

T5 T6

Eddy Current Dynamometer

Magnetic proximity

speed sensor

Exhaust

Flow meter

T3 T4

T1 T2

Cooling Water

Calorimeter

Fuel measuring unit

MPFI unit Fuel

Inlet

39

Useful data:

Parameter Value

Cylinder diameter (D) 0.074 m Cylinder Stroke (L) 0.0755 m Specific heat of water (Cp) 4.187 kJ/kg o C Specific gravity of fuel 0.85 kg/L

Calorific value of fuel used (Cv) 42000 kJ/kg o C Density of air () 1.17 kg/m3

Dynamometer Water Cooled Eddy Current Dynamometer which make use of the principle of

electro-magnetic induction to develop torque and dissipate power has been installed

for loading the engine. A toothed rotor of high-permeability steel rotates with a fine

clearance between water-cooled steel loss plates. A magnetic field parallel to the

machine axis is generated by two annular coils and motion of the rotor gives rise to

changes in the distribution of magnetic flux in the loss plates.

This in turn gives rise to circulating eddy currents and the dissipation of power

in the form of electrical resistive losses. Energy is transferred in the form of heat to

cooling water circulating through passages in the loss plates, while some cooling is

achieved by the radial flow of air in the gaps between rotor and plates.

Power is controlled by varying the current supplied to the annular exciting

coils, and very rapid load changes are possible.

40

Instrumentation for measuring various inputs/outputs

All the instrumentation incorporated is PC based as well as with local

indicators. The various factors to be measured as follows:

(a) Fuel measurement This is done by using gravimetric sensor. This instrument is placed on

a separate stand. The fuel tank is mounted inside the fuel sensor box. A

special design ensures almost nil transmission of vibration to the fuel sensor.

The amount of fuel consumed is determined by software/hardware by

deducting the final reading of fuel weight from initial reading of fuel weight

and dividing it by a fixed time interval.

(b) Air Flow measurement Airflow is measured using a vane type anemometer placed inline of

suction air.

(c) Exhaust gas heat loss measurement Exhaust gases from the engine passes through the flexible hose to the

calorimeter. The calorimeter is mounted on a stand and supports. Exhaust gas

enters into the calorimeter through the calorimeter exhaust gas inlet. Heat is

exchanged by circulating water through a copper pipe in the calorimeter.

Sensors mounted at various position measures the temperatures at that point.

(d) Temperature measurement The temperature at different points is measured using Platinum RTDs

and displayed on PC. The points are

i. Calorimeter exhaust gas inlet temperature

ii. Calorimeter exhaust gas outlet temperature

41

iii. Calorimeter water inlet temperature

iv. Calorimeter water outlet temperature

v. Engine cooling water inlet temperature

vi. Engine cooling water outlet temperature

vii. Ambient temperature

(e) Speed Measurement The speed of an Engine measured by a Proximity magnetic sensor

and is directly displayed on PC.

(f) Load Measurement Load cell is mounted on the dynamometer to measure the load on the

engine.

(g) Calorimeter Water Flow-rate Transmitter A Wheel type flow rate measuring device measures the flow rate to

the calorimeter used measuring the heat carried by exhaust gases.

(h) Data Acquisition software Data acquisition software is provided to collect the data from various

points of the apparatus directly.

THEORY Fundamentals of Fuel Injection

MPFI stands for 'multi point (electronic) fuel injection'. This system injects fuel into individual cylinders, based on commands from the on board engine management system

computer popularly known as the Engine Control Unit/ECU.

MPFI Systems can either be: a) Sequential i.e direct injection into individual cylinders against their suction strokes, or b) Simultaneous i.e together for all the four or whatever the number of cylinders, or c) Group i.e into Cylinder-Pairs.

These techniques result not only in better power balance amongst the cylinders but

also in higher output from each one of them, along with faster throttle response.

42

Of these variants of MPFI, 'Sequential' is the best from the above considerations of power

balance/output.

The Fuel Injectors are precision built Solenoid Valves, something like Washing Machine Water inlet Valves. These have either single or multiple Orifices which spray

fuel into the Fuel inlet manifold of a Cylinder upon actuation, from a common Rail/Header

pressurised to around 3 bar, fed by a high pressure electrically drive fuel pump inside the

Petrol tank of the Car.

The on-board ECU primarily controls the Ignition Timing and quantity of fuel to be

injected. The latter is achieved by means of controlling the duration for which the Injector solenoid valve coil is kept energized popularly known as the pulse-width.

In general, an ECU in turn is controlled by the data input from a set of SENSORS

located all over the Engine and its Auxiliaries. These detect the various operating states of

the Engine and the performance desired out of it. Such Sensors constantly monitor :

1) Ambient Temperature, 2) Engine Coolant Temp, 3) Exhaust/manifold temp., 4) Exhaust O2 content, 5) Inlet manifold vacuum, 6) Throttle position, 7) Engine rpm, 8) Vehicle road speed, 9) Crankshaft position, 10) Camshaft position, etc.

Based on a programmed interpretation of all this input data, the ECU gives the

various commands to the Engines fuel intake and spark ignition timing systems, to deliver

an overall satisfactory performance of the Engine from start to shut down, including

emission control.

PROCEDURE:

1. Start the data acquisition software by running the DAS.EXE file from the shortcut

provided on desktop.

2. Ensure that the communication cables are connected to serial ports of the PC correctly.

3. Fill petrol in the fuel tank.

43

4. Switch on the supply to the control panel and switch on the dynamometer controller.

Warm up time is 15 min. If any of annunciations LED glows, as soon as the unit is

switched on, press reset button. Annunciation should become off.

5. Ensure that sufficient water flow rate is maintained for engine, dynamometer and the

pressure sensor cooling arrangement.

6. Ensure that the engine is not loaded.

7. Ensure that the accelerator is at minimum position that is the engine is at idling speed.

8. Open the valve of the fuel supply to fill in fuel of required quantity.

9. Take the Engine Starter switch to position 1. Wait for 2 to 3 seconds. Take the switch to

Starter position momentarily. Once the engine starts, leave the switch, it comes back to

position 1

10. Let the engine run for 1 minute under no load conditions.

11. Note the readings as per the Observation Table.

12. Open the throttle gradually to bring increase speed to around 3000rpm.

13. While increasing the load on the engine, its speed may reduce. Use throttle to adjust the speed. Also increase the load gradually to 1 kgf and speed to 2500 rpm.

14. To acquire fuel consumption reading, wait for the reading of Fuel Consumption (on PC) to change once. Press LOG ONCE button. Now the data is stored.

The hardware/software measures the difference in the fuel weight every 60 seconds

approximately. The TFC reading is 0 for the first 60 seconds. It is updated every 60

seconds approximately. Hence it is important to wait and ensure that correct TFC reading

is displayed on the screen before logging the data. Note that the Fuel consumption

displayed refreshed every 60 seconds approximately.

15. To obtain the next set of reading, gradually increase the load while keeping the throttle

opening constant.

16. Repeat the above two steps to log the readings for the engine at different speeds while

ensuring that the engine does not get overloaded and sound abnormal.

17. After complete the test, gradually unload the engine.

44

18. Simultaneously, if required, gradually close the throttle and take the speed to idling

speed.

19. Take the Engine Starter switch to position 0. The engine stops.

20. Switch Off the water supply after about 2 minutes.

21. Empty the Measuring Cylinder of fuel measurement arrangement.

22. Save the data acquisitioned before closing the program system.

23. To obtain the observations and calculations (Calculation table)Select "Analysis" on the drop down menu. Go to "Calculations table" option and click on it.

24. To obtain the Heat balance (Heat balance table) Select "Analysis" on the drop down menu. Go to "Heat balance table" option and click on it.

25. To obtain graphs, Select "Analysis" on the drop down menu. Go to "Graph" option and

click on it. Now an option window appears. Select the variable to be kept on X-asis first

and then the variable for Y-axis. Select the data of the experiment and refresh. The

selected graph appears on screen. If one of the values in the readings set is abnormal,

deselect that particular value when selecting data for obtaining a representative graph.

26. Take the graph and other required data for printing by print screen option and pasting it in

the paint software. Insert these printouts suitably in your report.


Brake Th verses N BSFC verses N Heat balance chart

PRECAUTIONS

1. In case of emergency, press Mushroom switch marked Emergency OFF to shut the

engine off.

2. Check the cooling system of the engine and the dynamometer. Do not run engine when

there is no water supply for engine and the dynamometer cooling. Ensure that pressure

sensor water-cooling is "ON" before opening the valve at the pressure tapping.

45

3. Do not run engine without lubrication oil in `Lubrication oil pump'. Oil sump must have

sufficient oil up to the level. Fill up if necessary up to the level marked on the oil level

indicator. Use 15W40 oil for engine.

4. Do not let engine speed exceed 4000 rpm under any condition. Do not let the exhaust

temperature exceed 5000C.

5. Do not start the engine while it is loaded.

6. Always start engine with throttle at idle position.

7. Avoid loading the engine to its maximum capacity suddenly.

8. Do not let the engine oil temperature shoot up high.

9. While engine is loaded, if the power supply to the dynamometer controller fails, the

engine speed will increase to a dangerous level. To avoid this situation, provision is made

so that the engine shuts down as soon as there is no power to the control panel.

10. Engine will not start when power to a control Panel is Off.

11. When not in use, ensure that Measuring Cylinder of fuel measurement unit is empty.

Prolonged dead weight on the Measuring Cylinder can damage the sensor beyond

repair.

Important Points

(a). Engine will not start when power to control panel. is off (b). operate/reset switch should be in operate mode (c). if the digital indicator shows RPM as Zero or Low Value, take operate/reset switch

to operate mode.

(d) If any fault occur, visual annunciation is given and the dynamometer is unloaded. In such a situation, switch OFF the engine, remove the fault. Press RESET button provided on the

Dynamometer controller panel. If the fault is rectified, the LED will not glow. You are

now ready to use the test rig again.

(e) If at any stage engine RPM indicated on the digital indicator and that on PC differ substantially, do the following one by one and see if it match.

(i)Put off P-theta switch in Reset mode for 5 sec. and then back to Operate. (ii)Press Reset button of Dynamometer controller

(iii)Switch off dynamometer controller using switch provided on it.

46

Some useful sample data and graphs from Data Acquisition System

49

EXPERIMENT NO. 12

AIM :

(i) TO PLOT PRESSURE DISTRIBUTION ON THE PROFILE OF A CYLINDER PLACED IN THE LAMINAR FLOW OF AIR.

(ii) TO PLOT PRESSURE DISTRIBUTION ON THE PROFILE OF NACA 0018 AIRFOIL PLACED IN THE LAMINAR FLOW OF AIR BY POSITIONING IT AT VARIOUS VALUES OF THE ANGLE OF INCIDENCE .

DIAGRAMS

Profile of the Cylinder

Profile of the airfoil

50

EQUIPMENT USED

Open circuit wind tunnel can be used to study the pressure distribution and lift-drag characteristics of airfoils, cylinder, etc. Reynolds number up to 2,500,000 per meter can be achieved with this tunnel.

Description

The wind tunnel is of suction type with an axial flow fan driven by a variable speed DC motor (see Figure 1). It consists of an entrance section with a bell mouth inlet containing a flow straightener, screens, and a straw honeycomb. This section is followed by a 6.25:1 contraction section, the test section, a diffuser and the duct containing the axial flow fan. The whole unit is supported on steel frames. The complete wind tunnel except the test section is constructed of M.S. iron sheets for strength and rigidity. The test section is made of plywood and has Plexiglas windows for visual observation of flow phenomena. The control of the DC motor is by a rectifier controlled variable speed drive.

Specifications

1. The total length of the wind tunnel is about 5.0m. The axial flow fan and the duct is 0.6m long. The maximum height is about 2.0m. 2. Test section of 30cm x 30cm cross section and 100cm length with thick Plexiglas window. 3. Axial flow fan with aluminium cast airfoil shaped blades driven by a 5.0kW DC motor mounted outside the duct. The drive is through a belt pulley drive. 4. The test section velocity is varied by changing the DC motor speed.

Accessories

1. NACA 0018 airfoil (Axial chord - 16cm, span - 29cm) with pressure taps to determine the pressure distribution (see Figure 2 for pressure tap location).

2. Cylinder (Diameter - 8.9cm, span - 25.8cm) with pressure taps to determine the pressure distribution (see Figure 2 for pressure tap location).

3. Prandtl type pitot - static tube with traverse mechanism to measure the flow velocity in test section.

4. U-tube manometer for use with pitot tube.

51

5. Multi-limbed manometer for measuring the static pressure distribution in the airfoil and cylinder.

OPERATING PROCEDURE

Before the fan motor is turned on, the multi-limb manometer has to be prepared. The following sections describe the initial steps to be followed in preparing the instruments.

Preparing the multi-limbed manometer: Connect the manometer limbs to the various static pressure taps of the airfoil (or the cylinder) and fill the manometer reservoir with water.

Changing the incidence of the airfoil: The incidence angle is changed by loosening the bolts and manually positioning the airfoil at the required incidence angle.

Starting the wind tunnel axial flow fan

1. The rectifier control panel is connected to a 440 volts three phase power supply using suitable rating wire (5kW capacity). 2. Connect the DC motor with the control panel through the 4 wires- A, AA (armature wires) and Z, ZZ (field coil wires) properly. 3. Ensure that the speed control knob is at minimum and turn on the main power switch. 4. Press the motor start button and then turn the speed control knob slowly and smoothly while monitoring the reading of ammeter to keep it well below 5A.

5. Obtain the required test section velocity which can be observed from the U-tube manometer connected to the Pitot tube. It is advisable to limit the test section q to about 5cm of water column. This will correspond to about 60% in the control panel rheostat.

6. Obtain the reading of different manometers giving the pressure distribution across the profile of the model being tested for a particular wind velocity

CALCULATIONS

1. To determine velocity from Pitot-tube - Let the difference in manometer water level = q cm of water Velocity V = water air2gq( /100 )

52

i.e., V = 13.0 q m/sec

2. Static Pressure coefficient Cp - Cp = (P-Pref)/q Here, Pref = Patm for airfoil = P0deg - q for cylinder

Note: In multi-limb manometer, due to the position of scales higher numbers denote lower pressures. Hence, scale readings are read as negative values.

PRECAUTIONS

1. DO NOT SWITCH ON THE STATOR/ARMATURE COIL SWITCHES WITHOUT VERIFYING THAT THE VARIAC IS BROUGHT TO ZERO.

2. ALSO, DO NOT SWITCH OFF THE STATOR/ARMATURE COIL SWITCHES WITHOUT BRINGING THE VARIAC TO ZERO.

3. Increase the speed of the motor gradually ensuring that the ammeter reading is restricted up to 5A.

4. Do not operate the DC motor at very low inlet supply voltage (less than 350-360 Volts).

5. Limit the test section velocity head corresponding to about 5cm of water column. This will correspond to about 60% in the control panel rheostat.

53

EXPERIMENT NO. 13

AIM: TO DRAW THE VALVE TIMING DIAGRAM FOR THE GIVENCUT-SECTION MODEL OF A DIESEL ENGINE.

EQUIPMENT USED

Cut section models of the single cylinder diesel engine

PROCEDURE FOR DRAWING THE VALVE TIMING DIAGRAM:

First, identify and mark the positions TDC and BDC of the cylinder. Now mark the

same positions on the flywheel by averaging method. The experiment should be done with

respect to this cylinder only. Rotate the flywheel in the anticlockwise direction and go

through the four strokes.

(a) Inlet valve : Find out the exact positions where the inlet valve opens and closes.The inlet valve opens before TDC. This is to ensure that the valve will be fully open and the fresh

charge starts to flow into the cylinder as soon as possible after TDC.

As the piston moves out in the suction stroke, the fresh charge is drawn in through the

inlet valve. When the piston reaches the BDC and starts to move in the compression stroke,

the inertia of the entering fresh charge tends to cause it to continue to move into the cylinder.

To take advantage of this, the inlet valve is closed after BDC so that maximum air is taken in.

Otherwise sufficient charge may not enter the cylinder due to the high speed of the piston,

which may result in partial combustion. This decreases the power output.

(b) Exhaust valve: Find out the positions where the exhaust valve opens and closes. The exhaust valve opens before BDC so that the high pressure burnt up gases are effectively

54

removed from the cylinder by their own expansion. But opening the exhaust valve earlier

reduces the pressure near the end of the power stroke and causes some loss of useful work on

this stroke.

The exhaust valve closes after TDC so that the incoming gases through the inlet valve

force the burnt gases at the top of the piston (clearance volume) to leave. This results in increased volumetric efficiency.

TO LEARN MORE, FIND THE ANSWERS TO THE FOLLOWING QUESTIONS

1. What are the differences between 4-stroke and 2 - stroke engines and their relative merits

and demerits?

2. Compare S.I. engines with CI. Engines with reference to the following:

(a) Fuel used (b) Working cycle (c) Method of ignition (d) Method of fuel supply (e) Method of governing

55

EXPERIMENT NO. 14

AIM: STUDY THE CONSTRUCTIONAL FEATURES OF IC ENGINES WITH THE HELP OF CUT-SECTION MODEL MULTI-CYLINDER PETROL ENGINE AND DIESEL ENGINE

EQUIPMENT USED: Cut section models of the single cylinder diesel engine, Three cylinder petrol engine (Maruti 800).

CONSTRUCTIONAL FEATURE OF IC ENGINES Internal Combustion (IC) engines are widely used as prime movers for Vehicular

propulsion and electricity generators. These are called as IC engines because the fuel is burnt

inside the engine cylinder. In IC engines, chemical energy is converted to mechanical energy.

There are two basic types of IC engines the reciprocating type, which is very widely used and

the rotary type, like the Wankel engine.

IC engines are also classified as four stroke and two stroke engines based on the

number of strokes required to complete a cycle. In a four stroke engine, the charge is taken in

during the suction stroke as the piston moves in the cylinder. Compression stroke takes place

when the charge is compressed by the piston to occupy the clearance volume. Now ignition

takes place and the high pressure gases exert a force on the piston resulting in power stroke.

The expelling of burnt up gases takes place during exhaust stroke. Valves are used to let in

and let out gases.

In a two stroke engine (a cycle is completed in two strokes) the work of the Inlet end exhaust is done by a separate pump or blower when the piston is at the end of its stroke. The

other two strokes remain the same, No valves are necessary in this type of engines.

Internal combustion engines may also be classified based on the number of cylinders

as well as their alignment. The multi cylinder engines help in reducing the amplitude of

fluctuations in single cylinder engines. This way the vibrations are less severe and the

dynamometer of smaller moment of inertia may be sufficient. Multi cylinder IC engines can

be either horizontal, vertical, V shaped or inline engines, based on the orientation of

cylinders.

56

IC engines can be classified as Petrol and Diesel engine depending on the fuel used.

Petrol engines are also called spark ignition since a spark introduced at the end of

compression stroke ignites the air-fuel mixture. Diesel engines are called Compression

ignition also as only air is taken in during intake stroke and compressed. Diesel is sprayed in

atomized form and the high temperature compressed air ignites the mixture. They may be air

cooled or water-coo1ed.

Loading devices like dynamometers are used to measure the engine power. The types

of dynamometers used are external friction type, D.C. generator type, magnetic and hydraulic

type.

Lubrication is done so that the moving parts move with ease and without metal-to-

metal contact. The main purpose of a lubricating system is to get oil to all the moving parts.

The basic types of lubrication systems available are force and splash type, ring and

centrifugal type, etc.

VARIOUS PARTS OF AN IC ENGINE

Following are the main components of an engine.

1. Cylinder Block and Head:

Cylinder Block forms the base of the engine. The cylinder head is made of a single

casting. Cylinder Head is bolted on the top of the cylinder block. It has passages for oil and

water circulation. It accommodates valves, spark plugs/ injectors (in the case of diesel engines) and heater plug. A combustion chamber is also provided in some cylinder heads. In the case of the overhead valve system, the cylinder head supports the rocker shaft assembly.

The lower surface of the cylinder head is machined to the specified accuracy and gasket is

used in between the cylinder head and cylinder block to avoid leakage.

Material: Cast iron, aluminium alloy.

2. Liners:

A liner is a thin, cast iron, circular shell which is centrifugally cast. It contains

chromium for hardness. It protects the cylinder block from rapid wear and damage due to

57

combustion. The life of the cylinder block is increased by using a liner, since the block does

not bear combustion pressure and temperature directly.

Materials: nitrided steel, nitrided cast iron, chromium-coated alloy steel.

Functions of a Valve are:

1. To open and close the inlet and exhaust passages of the cylinder.

2. To dissipate heat, through its seat to the cylinder head.

Materials :

Inlet valve: Nickel steel alloy, stellite facing.

Exhaust valve: Silico-chrome alloy steel, sodium filled valves.

4. Valve Operating Mechanisms: Two types of valve operating mechanism are used in engines. They are as follows.

Side valve mechanism

Overhead valve mechanism

5. Piston : A piston is of a cylindrical shape which reciprocates inside the cylinder bore. The main

functions of the pistons are:

to transmit the power developed by fuel combustion to the crankshaft through the

connecting rod

to transfer the heat generated due to combustion to the cylinder wall.

A piston should be:

able to withstand high temperature and pressure of combustion

a good conductor of heat

light enough to minimize the inertia load.

58

5. Piston Rings 5.1 Compression Rings

These rings effectively seal the compression pressure and the leakage of the

combustion gases. These are fitted in the top grooves. They also transfer heat from the

piston to the cylinder walls. These rings vary in their cross-section.

The following types of compression rings are used.

5.2 Oil Control Rings

The main purpose of an oil ring (2) is to scrape the excess oil from the liner and drain it back to the oil sump during the downward movement of the piston. It prevents

the oil from reaching the combustion chamber. One or two oil control rings are used

in a piston. If two rings are used, one is fitted above and the other is fitted below the

gudgeon pin in the piston.

These rings exert enough pressure on the cylinder wall to scrape the oil film. To

keep the sealing and avoid metal-to- metal contact, a thin film of oil stays on the liner.

These rings are provided with drain holes or slots. These slots allow the scraped oil to

reach the oil sump through the piston holes.

Material: high grade cast iron.

6. Piston Pins :

The piston pin or gudgeon pin connects the piston with the connecting rod. It should

be strong enough to transmit power and withstand pressure of combustion. Piston pins are

made hollow to reduce inertia load due to the reciprocating motion.

Material: nickel/chromium alloy steel.

59

7. Connecting Rod :

It is fitted in between the piston and crankshaft. It converts the reciprocating motion

of the piston to the rotary motion in the crankshaft. It must be light and strong enough to

withstand stress and twisting forces.

ENGINE COOLING From the viewpoint of converting heat into mechanical energy, it follows that if each

piston accomplished its power stroke starting at the temperature of combustion, such an

engine would in theory be highly efficient. To achieve this in practice, however, would

require unacceptably high operating temperatures with adverse effects on both engine

lubrication and materials. Excessively high operating temperatures would cause breakdown

of the lubricating oil films, resulting in undue wearing and possible seizure of the working

parts.

For these reasons the engine must be provided with a system of cooling, so that it can

be maintained at its most efficient practicable operating temperature. This generally means

that the temperature of the cylinder walls should not exceed about 250C, whereas the actual

temperature of the cylinder gases during combustion may reach ten times this figure.

Conversely, there is no merit in operating the engine too cool since this would reduce thermal

efficiency and therefore increase fuel consumption.

In practice, motor vehicle engines are designed either for indirect cooling by air

through the medium of water or, less commonly, for direct cooling by air. Expressed in

everyday language, these tow systems are known simply as water-cooling and air-cooling

respectively. Each system possesses certain advantages over the other.

Air CoolingWith air cooling, the engine structure is directly cooled by forcing air to flow over its

high-temperature surfaces. These finned to present a greater cooling surface area to the air. In

some non-motor-cycle applications air is forced to circulate by means of a powerful fan.

60

Advantages of air-cooling

1. Warm-up of the engine is more rapid because heat is less readily transferred

from the engine metal to the air being circulated around it.

2. The system is inherently more reliable because air cooling is immune to either

freezing or boiling of the coolant around the cylinder heads and cylinders, and

to the loss of coolant. It is also free from any build up of corrosive products

that can restrict coolant passages.

3. Less maintenance is required in service because there is neither the

requirement to check the cooling medium for level and condition, nor the need

to inspect rubber connecting hoses for signs of leakage.

Water Cooling In water cooling system water is circulated through a water jacket, which surrounds

the heated parts like cylinder walls, combustion chamber, valve ports etc., of the engine. The

heated coolant losses heat in the radiator. Radiator fan assists the through flow of cooling air

for the heated coolant.

Advantages of water-cooling

1. Cooling is more uniform because heat is transferred with greater rapidity from

the engine metal surfaces to water than it is to air.

2. Cooling is more constant because the time taken for the water to rise through a

given temperature range is longer than that for the same mass of air.

Advantageous in maintaining a more nearly constant operating temperature.

3. Interior heating for the vehicle is improved because outside air may be

directed through a heat exchanger.

TO LEARN MORE, FIND THE ANSWERS TO THE FOLLOWING QUESTIONS

1. Describe the working of a single jet carburetor and give its limitations. How these limitations are taken care in actual carburetor.

2. Describe the working of fuel pump used in diesel engines.

61

3. Draw the diagram for an automotive vehicle transmission system and explain the

function of each component.

4. What is the need for a lubrication system in an internal combustion engine and what

are the various kind of lubrication systems available in internal combustion engines.

5. Discuss the innovations in the combustion chamber designs.

6. What is MPFI? Discuss its advantages over the conventional systems.

Pull-Out

Sheets

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P (kg

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V (kg

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V (mm

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Documents

Lab Manual PMFM