CE6461 - Fluid Mechanics and Machinery Laboratory.pdf

8/10/2019 CE6461 - Fluid Mechanics and Machinery Laboratory.pdf

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CE6461 FLUID MECHANICS AND MACHINERY LABORATORY L T P C0 0 3 2

OBJECTIVES:Upon Completion of this subject, the students can able to have hands on experience in flow

measurements using different devices and also perform calculation related to losses in pipes and

also perform characteristic study of pumps, turbines etc.,

LIST OF EXPERIMENTS1. Determination of the Coefficient of discharge of given Orifice meter.

2. Determination of the Coefficient of discharge of given Venturimeter.

3. Calculation of the rate of flow using Rota meter.

4. Determination of friction factor for a given set of pipes.

5. Conducting experiments and drawing the characteristic curves of centrifugal pump/

submergible pump

6. Conducting experiments and drawing the characteristic curves of reciprocating pump.

7. Conducting experiments and drawing the characteristic curves of Gear pump.

8. Conducting experiments and drawing the characteristic curves of Pelton wheel.

9. Conducting experiments and drawing the characteristics curves of Francis turbine.

10.Conducting experiments and drawing the characteristic curves of Kaplan turbine.

TOTAL: 45 PERIODSOUTCOMES:

Ability to use the measurement equipmentsfor flow measurement Ability to do performance trust on different fluid machinery

S. NO. NAME OF THE EQUIPMENT Qty.

1 Orifice meter setup 1

2 Venturimeter setup 1

3 Rotameter setup 1

4 Pipe Flow analysis setup 1

5 Centrifugal pump/submergible pump setup 1

6 Reciprocating pump setup 1

7 Gear pump setup 1

8 Pelton wheel setup 1

9 Francis turbine setup 1

10 Kaplan turbine setup 1


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INDEX

S.No DATE NAME OF THE EXPERIMENT MARK SIGNATURE

1

2

3

4

5

6

7

8

9

10

11

12

Completed date:

Average Mark: Staff - in - charge


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Ex. No. : DETERMINATION OF THE CO EFFICIENT OFDISCHARGE OF GIVEN ORIFICE METERDate :

Aim:

To determine the coefficient of discharge of given Orifice meter.

Apparatus Required:

1. Orifice meter

2. Differential U tube

3. Collecting tank

4. Stop watch

5. Scale

Description:

1. Header tank with flange assembly to fit the orifice installed in the vertical plane of the tank

side.2. A vertical sight glass (piezometer) fitter with the tank to record the water level in the tank.

3. A constant steady supply of water with a means of varying the flow rate by using by pass

valve.

4. A traveling distance point gauge to measure the co-ordinates x and y.

5. Deliver tank with piezometer to measure discharge through the orifice.

Theory:

An orifice may be defined as an opening provided in the side or bottom of a tank for the

purpose of discharge. It should be noted that the opening will be considered as an orifice only when

the level of the liquid on the upstream side is above the top of the orifice. The purpose of an orifice

is to measure the flow. An orifice of area a provided in the side of atank. Let H be the head of the

liquid above the centre of the orifice. The liquid stream discharged by the orifice is called a jet. The

liquid particles approach the orifice from all direction and after passing through the orifice the jet

contracts and reaches a minimum sectional area at certain section is called as vena contract. The

distance of the vena contract from the orifice is approximately equal to half the diameter of the

orifice. The stream lines of flow are converging up to vena contract and beyond this section the

stream lines are parallel.

Experimental Procedure:

1. Measure the diameter d of the vertical orifice. Admit the water supply to the header tank and

for conditions allowed to steady to give a constant head H. Measure the head of water H

above the centre line of the orifices.

2. The co-ordinates at the vertical jet are observed on the scales of the traveling distance gauge,

by touching the jet from the pointer of hook then after a reasonable distance along x-axis

where there is a stream line flow, a section of jet is chosen and on similar lines, co-ordinates

of this section are measured. After deducing the initial readings of the co-ordinates of vena

contract from the final readings, the vertical and horizontal distances of the section chosen


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are found out. From this, the coefficient of velocity can be calculated by the above mentioned

formula.

3. Collect the water discharging from the orifice in a measuring tank of known dimensions and

measure the rise of water level in the measuring tank for certain period of time t sec. from

these values the coefficient of discharge can be calculated. Coefficient of contraction can

also be obtained dividing Cdwith Cv.

4. The above readings are repeatedly taken for different constant heads and are tabulated.

Formulae to be used:

1. Theoretical discharge through the orificemeter, QT=a1a22 g H

m3/s

a1 = Area of cross-section of the pipe

a2 = Area of cross-section of the throat

g = Acceleration due to gravity

H = Drop in pressure head between the inlet and throat of the orificemeter

= 1 ~ = Specific gravity of the manometric liquid = Specific gravity of water

& = Manometer readings.

2. Actual discharge through the orificemeter, QA=

m3/s

Where,

A = Area of cross-section of the collecting tank in m2

R = Rise of water level for time t secs in m.

t = Time taken in seconds for R m rise of water3. Coefficient of discharge of the orificemeter, Cd=

4. To find the values of k & n:

Theoretical discharge, QT =a1a22gH

m3/s

It can be written as, QT = kHn m3/sWhere, k = a1a22g

n = 0.5

Similarly QA = kHnm3/s

Taking logarithms on both sides,

log = logk + nlogHlog = nlogH + logk


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This equation is similar to that of a straight line. Hence if a curve is drawn with

logalong the y-axis and log H along the x-axis, then it will be a straight line of slope n andhaving y-axis intercept log k. Thus from that straight line, the values of k & n can be determined.

Graphical Method of Finding the value of Cd

1. Plot a curve QAVs H2. From the curve select two points and note down the values of QA and the corresponding

values of H.3. Find QA from QA= QA1~QA24. Find H from H = ()1 - ()25. Find QT using H

6. Cd=

QAQT

Graphs to be drawn:

1. QA Vs H2. logVs logH


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Table: Orificemeter

Size of the collecting tank = value of x =

S.

No.

Manometric reading Time taken

for R rise in

water level t

sec.

Drop in

pressure

head H

m

Theoretical

discharge QT

m3/s

Actual

discharge

QA

m3/s

H Cdh1 h2cm m cm m


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Model Calculation :(For Reading No_________)

Diameter of the pipe, D = m

Diameter of the throat, d = m

Height of mercury column in the right limb of the manometer, h1 = m

Height of mercury column in the left limb of the manometer, h2 = m

Time taken for the rise of x-units of water in the collecting

tank, t=

s

Value of x = m

Specific gravity of the manometric liquid, =Specific gravity of the water, Acceleration due to gravity, g m/s2

Drop in pressure head between the inlet and the throat of the

orificemeter H = 1 ~m

Area of cross-section of the pipe (a1) =D

4

=m2

Area of cross-section of the throat (a2) =D

4 =

m2

Area of cross-section of the collecting tank, A = m2

Theoretical discharge through the orificemeter

QT=a1a22 g H

m3/s = m3/s

Actual discharge through the orificemeter, QA=A x

= m3/s

Coefficient of discharge of the orificemeter, Cd= QQ =

Result:

1. The coefficient of discharge of the given orificemeter

i. By analytical method =

ii. By graphical method =

2. In the equation QA = k Hn m3/s

k = for the given orificemeter

n= for the given orificemeter

3. In the equation QT= k Hnm3/sk= for the given orificemeter

n= for the given orificemeter

and H is the drop in pressure head between the inlet of orificemeter and the throat or orifice in meters.


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Ex. No. : DETERMINATION OF THE CO EFFICIENT OFDISCHARGE OF GIVEN VENTURIMETERDate :

Aim:

1. To find the coefficient of discharge of the given venturimeter.

2. To find the coefficients k & n in the rating equation.3. To find the loss-coefficient K

Apparatus Required:

1. Venturimeter

2. Stop watch

3. Collecting tank

4. Differential U-tube

5. Manometer

6. Scale

Theory:A Venturimeteris a device which is used for measuring the rate of flow of fluid through

pipe line. The basic principle on which a venturimeter works is that by reducing the cross-sectional

area of the flow passage, a pressure difference is created between the inlet and throat & measurement

of the pressure difference enables the determination of the discharge through the pipe.

A Venturimeter consists of:

1. An inlet section followed by a convergent cone,

2. A cylindrical throat &

3. A gradually divergent cone.

The inlet section of the Venturimeter is of the same diameter as that of the pipe which is

followed by a convergent cone. The convergent cone is a short pipe which tapers from the original

size of the pipe to that of the throat of the Venturimeter. The throat of the venturimeter is a short

parallel side tube having its cross-sectional area smaller than that of the pipe. The divergent cone of

the venturimeter is gradually diverging pipe with its cross-sectional area increasing from that of the

throat to the original size of the pipe. At the inlet section & at the throat, of the venturimeter, pressure

taps are provided through pressure ring.

Venturimeter provides a construction in the flow area which produces an accelerated flow.

Consequently, there will be a fall in static pressure. Hence, the measurement of drop in static pressure

provides an accurate measure of the flow rate in the pipe. The application of Bernoullis Equation

between the inlet section and the throat section and the use of continuity equation leads to thefollowing expression for the flow rate.

Description:

The unit consists of three venturimeters of various sizes according to the diameter of various

pipes.

Each pipe is having the respective venturimeter with quick-action valves for pressure

tappings. The pressure tappings of the meters are connected to a common middle chamber, which is


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in turn, connected to a differential manometer. Water is let from the mains to the pipes through a

gate valve and water from the pipes can be collected in a collecting tank.

Venturimeter is the device for measuring flow in pipes. It is used for measuring rates of flow

in both incompressible and compressible fluids.

The value of Cd, is less than unity vary from 0.950.99 for Re>105. Venturimeters are not

suitable for very low velocities.

Practical Applications:

Venturimeter is commonly used for measurement of flow through pipes. Venturies are also

used in industries to measure the flow rate of gases and liquids. It is used for measuring rates of flow

in both compressible and incompressible fluids.


5. Theoretical discharge through the venturimeter, QT=a1a22 g H

m3/s

a1 = Area of cross-section of the pipea2 = Area of cross-section of the throat


H = Drop in pressure head between the inlet and throat of the venturimeter

= 1 ~ = Specific gravity of the manometric liquid = Specific gravity of water

& = Manometer readings.

6. Actual discharge through the venturimeter, QA= m3/s

Where,

A = Area of cross-section of the collecting tank in m2

R = Rise of water level for time t secs in m.

t = Time taken in seconds for R m rise of water7. Coefficient of discharge of the venturimeter, Cd=

8. To find the values of k & n:

Theoretical discharge, QT =

a1a22gH m

3

/s

It can be written as, QT = kHn m3/sWhere, k =

a1a22g

n = 0.5

Similarly QA = kHnm3/s


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Taking logarithms on both sides,

log = logk + nlogHlog = nlogH + logk

This equation is similar to that of a straight line. Hence if a curve is drawn with

logalong the y-axis and log H along the x-axis, then it will be a straight line of slope n andhaving y-axis intercept log k. Thus from that straight line, the values of k & n can be determined.

Graphical Method of Finding the value of Cd

7. Plot a curve QAVs H8. From the curve select two points and note down the values of QA and the corresponding

values of H.9. Find QA from QA= QA1~QA210.Find H from H = ()1 - ()211.Find QT using H12.Cd=

QAQT

Graphs to be drawn:

3. QA Vs H4. logVs logH

Procedure:

All the necessary instrumentations along with its accessories are readily connected. It is just

enough to follow the instructions below.

1. Fill-in the sump tank with clean water.

2. Keep the delivery valve closed.

3. Connect the power cable to 1 Ph, 220 V, 10 Amps with earth connection.

4. Switch-ON the Pump & open the delivery valve.

5. Open the corresponding ball valve of the Venturimeter pipe line.

6. Adjust the flow through the control valve of the pump.

7. Open the corresponding ball valves fitted to Venturi / Orifice tappings.

8. Note down the differential head reading in the Manometer. (Expel if any air is there by opening

the drain cocks provided with the Manometer).

9. Operate the Butterfly Valve to note down the collecting tank reading against the Known time

and Keep it open when the readings are not taken.

10. Change the flow rate & repeat the experiment.


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Table: Venturimeter

Size of the collecting tank = value of x =

S.

No.

Manometric reading Time taken

for R rise in

water level t

sec.

Drop in

pressure

head H

m

Theoretical

discharge QT

m3/s

Actual

discharge

QA

m3/s

H Cdh1 h2cm m cm m


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Model Calculation :(For Reading No_________)


Diameter of the throat, d = m

Height of mercury column in the right limb of the

manometer,

h1 =m

Height of mercury column in the left limb of the

manometer,

h2 =m

Time taken for the rise of x-units of water in the collecting

tank,

t =s

Value of x = m

Specific gravity of the manometric liquid, =Specific gravity of the water, Acceleration due to gravity, g m/s2


venturimeter H = 1 ~ mArea of cross-section of the pipe (a1) =

D4

=m2

Area of cross-section of the throat (a2) =D

4 =

m2

Area of cross-section of the collecting tank, A = m2

Theoretical discharge through the venturimeter

QT=a1a22 g H

m3/s = m

3/s

Actual discharge through the venturimeter, QA=A x

= m3/s

Coefficient of discharge of the venturimeter, Cd=QQ

=

Result:

4. The coefficient of discharge of the given venturimeter

i. By analytical method =

ii. By graphical method =

5. In the equation QA = k Hn m3/sk = for the given venturimeter

n= for the given venturimeter

6. In the equation QT= k Hnm3/s

k= for the given venturimeter

n= for the given venturimeter

and H is the drop in pressure head between the inlet of venturimeter and the throat or orifice in

meters.


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Ex. No. : CALCULATION OF THE RATE OF FLOW USINGROTA METER.Date :

Aim:

1. To find the coefficient of discharge of the given rotameter.

2. To calculate the pressure difference between the inlet and outlet of the rotameter.

Apparatus Required:

1. Rotometer setup

2. Measuring scale

3. Stopwatch.

Description

A rotatmeter is a device that measures the flow rate of liquid or gas in a closed tube.

A rotameter consists of a tapered tube of glass with a float inside that is pushed up by flowand pulled down by gravity. At a higher flow rate more area (between the float and the tube)

is needed to accommodate the flow, so the float rises. The float is shaped so that it rotates as

the fluid passes. The top edge of the float is compared with graduations on the glass to

measure the flow rate of the fluid.

The unit consists of two rotameters of various sizes according to the diameter of

various pipes.

Practical Applications:

Rotameter is commonly used for measurement of flow through pipes in closed circuit.

Procedure:

1. Open the valves corresponding to the given rotameter.

2. Adjust the control valve kept at the exit end of the apparatus to a desired flow rate

and maintain the flow steadily

3. Collect water in the collecting tank for a rise of x units and note down the time

taken to collect that amount of water.

4. Note down the reading on the rotameter for the corresponding discharge.

5. Adjust the gate valve to increase the rate of flow and repeat step 3 and 4.


1. Theoretical discharge QT = Rotameter reading

2. Actual discharge QA = A h 6 T litres / min.3. Co-efficient of Discharge, Cd = Ac Dischre Q

Theriic Dischre Q4. Velocity V = Q

m/s.5. Pressure difference PiPo = K V

+ Zo- ZiWhere

A = area of the measuring tank in m2

a = area of the pipe in m2

h = rise of water level in meters (say 10 cm)T = time in seconds for raise of water level


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K = loss coefficient (0.6),

Zo -

Zi

= Height of inlet and outlet levels of rotameter from a common datum.

V = Velocity of the water through the pipe.

g = Acceleration due to gravity.

Pi,Po

= Pressure at the inlet and outlet of rotameter.

Table 1 Rotameter

Diameter of the pipe = mm

S.

No

Time for (10 cm)

rise of water

(sec)

Actual

Discharge,

Qa.

(lpm)

Theoretical

Discharge

Qt

(lpm)

Cd=

V =

m/s

Pressure

Difference

Pi- Po

Result:

1. The coefficient of discharge of the given rotameter____________

Discussions:

1. The graph between actual and theoretical discharge.

2. Graph between pressure drop and discharge through the rotameter.


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Ex. No. : HEAD LOSS DUE TO FRICTION (MAJOR LOSS)Date :

Aim:To determine the Darcysfriction factor and the coefficient of friction of the given pipe.

Apparatus Required:

1. A pipe provided with inlet and outlet and pressure tapping

2. Differential u-tube manometer

3. Collecting tank with piezometer

4. Stopwatch

5. Scale

Theory:

A closed circuit of any cross-section used for flow of liquid is known as a pipe. In

hydraulics, generally, pipes are assumed to be running full and of circular cross section. Liquids

flowing through pipes are encountered with frictional resistance resulting in loss of head or

energy of liquids. This resistance is of two types depending upon the velocity of flow.

1. Viscous Resistance and

2. Frictional Resistance, due to different diameters.

The viscous resistance is due to the molecular attraction between the molecules of the

fluid. At low velocities, the fluid appeared to move in layer or lamina, and hence the nature of

this flow is termed laminar flow or Stream line. If the velocity of the liquid is steadily increased,

at certain velocity termed as the lower critical velocity the parallel bands of liquid will becomewavy. On further increase in the velocity these instabilities will increase in intensity until a

velocity corresponding to the upper critical velocity is attained. The region of flow bounded by

the lower and upper critical velocity is attained. The region of flow bounded by the lower and

upper critical velocities is termed the transition zone. For all further increase in velocity of flow

the streamline remains in a diffused state and the nature of this type of flow is termed turbulent.

In this case the flow is restricted by the friction between the liquid and the pipe surface which

is known as frictional resistance.

DEFINITIONS:

Laminar Flow:

A flow is said to be laminar, when the various fluid particles appear to move in layers

(or lamina) with one layer of fluid sliding smoothly over an adjacent layer. Thus in the

development of laminar flow, the viscosity of the fluids plays a significant role. Laminar flow

occurs when the viscous forces predominate over the inertial forces; it has been generally

accepted now that if Reynolds number is less than 2000, laminar flow is sustained in pipes.

Laminar flow is characterized by low velocity, narrow boundary and high viscosity. The loss

of head due to friction (hf) is directly proportional to velocity (V) in laminar flow through pipes

i.e., hfis proportional to V.Turbulent Flow:


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Turbulent flow is an irregular motion in which fluid particles move in an entirely

haphazard or disorderly manner that results in rapid and continuous mixing of the fluid particle.

It is characterized by high velocity and low viscosity. Turbulent flow occurs when inertial

forces predominate over viscous forces; and generally turbulent flows are considered to occur

in pipes at Reynolds number more than 4000. The loss of head due to friction (hf) in turbulentpipe flows varies as Vn, where, V is the velocity of flow and n varies from 1.72 to 2.0.

Transitional Flow:

The state of flow in between the laminar and turbulent flow is called as Transitional

Flow. That is, for pipe flow at Reynolds number between 2000 and 4000, transitional state of

flow prevails, which is a region of uncertain behavior. As change of state of flow cannot be

abrupt, the transition from one set of flow to another alternates back and forth between laminar

and turbulent, within the range of Re from 2000 to 4000.

Reynolds Number:

Reynolds number signifies the relative predominance of the inertia to the viscous forcesoccurring in a flow system. Thus it is the key to decide whether a flow is laminar or turbulent.

It is defined as the ration of inertia force to viscous force and is given by, Reynolds number,

Re = Inertia force / Viscous force. Or

Re = V D /

(for circular pipe).

Where, V = average velocity of flow.

D = Diameter of pipe.

= kinematic viscosity coefficient of the fluid = 1 x 10-6m2/ sec.

It may be pointed out that Reynolds number is a function of boundary geometry and for

non-circular conduits, it is given by Re = VL / , where L is a characteristic length defining the

boundary geometry.

Critical Reynolds Number & Critical Velocity:

The concept of critical Reynolds number and critical velocity is used to distinguish between

the regions of laminar, turbulent and transitional state of flow.

Critical state is occurs when flow changes from one state in to another. Lower critical Reynolds

number for flow of fluid in pipes is of greater importance as it indicates a condition belowwhich all turbulence entering the flow from any source will damped out by viscosity and thus

sets a limit below which laminar flow will always occur.

Experimentally, the value of lower critical Reynolds number has been found to be

approximately 2000 for flow through pipes.

Upper critical Reynolds number and upper critical velocity are the limiting Reynolds number

and limiting velocity above which the flow will always be turbulent, that is, it marks the upper

limit of laminar flow. The upper critical Reynolds number is indefinite, being dependent uponinitial disturbances affecting the flow, shape of entry to pipe, roughness of the boundary etc.


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By carefully conducting the experiment, laminar flows have been obtained at Reynolds number

has high as 14000. However the practical value of upper critical Reynolds number may be

considered to lie between 2700 to 4000 for pipe flows; the value of 4000 is generally accepted

as upper critical Reynolds number, above which flow in pipes in considered to be turbulent.

Between Reynolds number of 2000 and 4000 the transitional region exists in pipes.

Darcy-Weisbach Friction Factor:

Darcy Weisbach equation is commonly used for computing the loss of head due to

friction in pipes. It is given by,

hf= fLV2/D2g.

Where,

Hf= loss of head due to friction.

L = Length of pipe.

D = Diameter of Pipe.V = Mean Velocity of flow in the pipe.

F = Darcy weisbach friction factor.

The above equation indicates that the loss of energy head varies directly with velocity head

(V2/2g). Pipe length L and inversely with pipe diameter (D). The constant of proportionality

used in Darcy Weisbach equation, in the above form, f is called friction factor.

FORMULAE TO BE USED:

Head loss due to friction, hf= V

D =4 " V

D Where,

f = Darcys friction factor

f" = Coefficient of friction (Note : 4 f = f)L = Distance between the points connected to the manometerV = Velocity of flow in the pipe


D = Diameter of the pipe

Velocity of flow in the pipe, V =Q

Where

Q = Actual discharge through the pipea = Area of cross-section of the pipe

Actual discharge through the pipe, Q =Ax

Where,

A = Area of cross-section of the collecting tank

t = Time taken for raising x-units of water level in the collecting tank.

Head loss due to friction is also given by the equation, hf= 1 ~`Where,

h1& h2 = Manometer readings

= Specific gravity of the manometric liquid


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= Specific gravity of the liquid flowing through the pipe

PROCEDURE:

All the necessary instrumentations along with its accessories are readily connected. It is just

enough to follow the instructions below.1. Fill-in the sump tank with clean water.


3. Connect the power cable to 1 Ph, 220V. 10 Amps with earth connection.

4. Switch-ON the pump & open the delivery valve.


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Table: Head loss due to friction

Size of collecting tank=

S

No.

Manometer readingsHead loss due

to friction hf

m

Time taken

for x unit rise

in water level

t sec.

Discharge

through

the pipe Q

x10-3

Velocity of

flow V

m/s

V2

M/s2F F

h1 h2

cm m cm m


21/65

21

MODEL CALCULATION :(For Reading No_________)


Specific gravity of the manometric liquid, =Specific gravity of the liquid flowing thro the pipe, =Distance between the points connected to the manometer, L = mArea of cross-section of the collecting tank, A = m2

Acceleration due to gravity, g = m/s2

Manometer readings h1 = m

h2 = m

Time taken for x-unit rise of water level in the collecting tank, t = s

Value of x = m

Head loss due to friction. hf= 1 ~ = mArea of cross-section of pipe, a =

D

4

= m2

Actual discharge through the pipe, Q =Ax

= m3/s

Velocity of flow in the pipe, V =Q

= m/s

Darcys friction factor, f=h D

V Coefficient of friction, f=

h D4 V

Graph:

Head loss due to friction hfvs V2

Result:

The value of the Darcys friction factor of the given pipe is,

1. By analytical method =

2. By graphical method =

The value of the coefficient of friction of the given pipe is,

1. By analytical method =

2. By graphical method =


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22

Ex. No. : HEAD LOSS DUE TO FRICTION (MINOR LOSSES)Date :

Aim:1. To determine the head loss due to friction in Pipe Fittings and hence, to

determine the Head Loss Co-efficient .

2. To determine the equivalent length of a pipe of the given fittings which is fitted to

that particular pipe line?

Apparatus Required:

3. The Pipe lines in three different branches containing;

(i) Valves in one Line

(ii) Bends & Elbows in second line(iii) Collar, Union, Contraction &Expansion in the third line.

4. U-Tube Manometer connected across each fitting with change-over

Valves.

5. A constant steady supply of water using Centrifugal Pump with Valve

for changing the flow rate.

6. Measuring Tank with Stop Clock for measurement of flow rate.

7. The Sump Tank mounted below the Collecting Tank.

8. The Butterfly Valve for instantaneous dumping of collected water into the

Sump tank and the overflow pipe to facilitate to run the equipment on

Closed circuit basis

Theory:

Like the straight pipes produce the friction to the flow of fluid due to its inside

roughness, the pipe fittings such as Valves, Bends, Elbows, Reducers / Expanders, etc also

offer Resistance / Friction to the flow of fluid. While the head loss due to friction in straight

pipes is expressed by the standard formulae:

hf = V

d .... (a)

The head loss due to friction in pipe fittings is expressed by

Similar equation:K V

.... (b)

By equating (a) and (b), we get the factor K = f l/d where K is the local head loss

Co-efficient of pipe fittings (non-dimensional) expressed in terms of the friction factor (f),length (l) and diameter (d) of the pipe to which the particular type of fitting is fitted.


23/65

23

In the equations where the branches of pipes are used for flow analysis, all the

resistances offered by the fittings are expressed in equivalent length of pipe to which they

are fitted, namely; L = Kd/f .This is to be added to the length of the straight pipe of

diameter d with the friction factor f ( 0.025 generally assumed ), and the analysis isdone further. Note that the valve of K is to be evaluated from the formulae hf (pipe fitting)

=KV2/ 2g where V is the velocity of fluid flowing in the pipe line of diameter d to which

the pipe fitting is fitted.

Further, it is also be noted that, if in a branch of pipe lines, where the various

diameter pipes are involved, the similar kind of method is used for converting all the other pipe

of different diameters to the equivalent length of one particular diameter. This way the analysis

becomes simpler. In such cases, the equivalent length is calculated from the formulae;

L L1

L2

L3

--- = ----- + ----- + -----

d5 d15 d

25 d

35

Operating Procedures:

All the necessary instrumentation along with its accessories are readily connected. It is just

enough to follow the instructions below:

1. Fill-in the sump tank with clean water.


3. Connect the power cable to 1 Ph, 220V, 10 Ampsa. With earth connection.

4. Switch-ON the Pump & open the delivery valve.

5. Open the corresponding ball valve of the pipe line.

6. Adjust the flow through the control valve of the pump.

7. Open the corresponding ball valves.

8. Note down the differential head reading in the Mano-meter. (Expel if any air is there byopening the drain cocks provided with the Manometer)

9.

Operate the Butterfly Valve to note down the collecting tank readingAgainst the known time and keep it open when the readings are not

taken.

10.Change the flow rate & repeat the experiment for different diameterOf pipe fittings.


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24

Formulae to Be Used:

Data:

Area of Measuring Tank A = 0.075 m2

Acceleration due to Gravity g = 9.81 m/sec2

Diameter of Bigger pipe D = 27 mm Diameter of Smaller pipe d = 15 mm

1. Actual Discharge (Q):

A R where,

Q = ------------- m3/Sec 1000 is the conversion factor

1000 t from mm to m.

A = Area of Measuring Tank

= 0.075 m2R = Rise of water level in mm (Collecting Tank)

= 100 mm

t = Time for R mmof rise in water in Secs.

2. Loss of Head due to Fitting (hf) :

12.6 H

hf= ----------- mtrs

1000

Where,

H = Difference in Mercury column in mm of Hg in double column Manometer.

12.6 & 1000 are conversion factors.

3. Velocity Head (V):

Discharge Q Where,

V = ----------------------------- = ------- m/sec

Area of Inlet Section a1

a1= Area of pipe to which the fitting is fitted

=

4. Additional Friction Loss (K):

Loss of Head

K = --------------------

Velocity Head


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25

hf

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

(V2/2g)

Note:Additional frictional loss (K) for sudden contraction and sudden expansionis calculated from the formula as given below:

5. Additional Frictional Loss for sudden expansion (K) :

hf

K = --------------

(V1V2)2

2g

Q

V2= -----a2

Where,

a2= area of the smaller diameter = d2/4 = 1.77x10-4m2.

d = 15mm

6. Additional Frictional Loss for sudden contraction (K):

hf

K = ------------------

V2

0.5 x --------

2g


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26

TABLE: MINOR LOSSES

LOSS OF HEAD IN PIPE FITTINGS (MINOR LOSSES)

AREA OF COLLECTING TANK = 0.075m2

DIAMETER OF 1" PIPE =27 mm

DIAMETER OF 1/2" PIPE =15 mm

Area of

inletsection

(a1)

ROTAMET

ERREADING

in LPM

TYPE OFPIPE

FITTING

MANOMETER READING

mm of Hg

TIME TAKEN

FOR 10 cmRISE OF

WATER t 's'

Collectingtank AREA

(A) in mm2

DischargeQ in m3/sec

Loss ofHead hf in

m

Velocity(V) in

m/sec

Velocityhead in m

Addition

alFrictiona

l Loss(K)

10

Non Return

valve

20

30

40

50

10

Gate Valve

20

30

40

50

10

Wheel

Valve

20

30

40

50


27/65

27

10

Union

20

30

40

50

10

Collar

20

3040

50

10

90oShort

bend

20

30

40

50

10

90oLongbend

20

30

40

50

10

45oShort

bend

20

30

40

50


28/65

28

10

45olong

bend

20

30

40

50

Area of

inletsection(a1)

Area of

inlet section(a2)

VALVEPOSITION

TYPE OF

PIPEFITTING

MANOMETER

READING mmof Hg

TIMETAKEN

FOR 10cmRISE OF

WATER t 's'

AREA (A)in mm2

Discharge

Q inm3/sec

Loss of

Head hfin m

Velocity

(V1) inm/sec

Velocity

(V2) inm/sec

Additio

nalfrictional Loss

Additional

frictionalLoss

10

SuddenContraction

20

30

40

50

10

SuddenExpension

20

30

40

50

Result:

Head loss due to friction is ___________.


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29

Ex. No. : CHARACTERISTICS TEST ON CENTRIFUGAL PUMPDate :Aim:

To study the performance characteristics of a centrifugal pump and to determine the

characteristic with maximum efficiency.

Apparatus Required:

1. Centrifugal pump setup

2. Meter scale

3. Stop watch

Introduction:

In general a pump may be defined as a mechanical device which, when interposed in a

pipe line, converts the mechanical energy supplied to it from some external source into

hydraulic energy, thus resulting in the flow of liquid from lower potential to higher potential.The pumps are of major concern to most engineers and technicians. The types of pump vary

in principle and design. The selection of the pump for any particular applications is to be done

by understanding their characteristics. The most commonly used pumps for domestic,

agriculture and industries are; Centrifugal, Piston, Axial flow (stage pumps), Air jet,

Diaphragm and Turbine pumps. Most of these pumps fall into the main class, namely;

Rotodynamic, Reciprocating (positive displacement), Fluid (air) operated pumps.

While the principle of operation of other pumps is discussed elsewhere, the centrifugal

pump which is of present concern falls into the category of Rotodynamic pumps. In this pump,

the liquid is made to rotate in a closed chamber (volute casing) thus creating a centrifugal actionwhich gradually built up the pressure gradient towards outlet, thus resulting in the continuous

flow. These pumps compared to reciprocating pumps are simple in construction, more suitable

for handling viscous, turbid (muddy) liquids, can be directly coupled to high speed electric

motors (without any speed reduction ) & easy to maintain. But, their hydraulic heads at low

flow rates is limited, and hence not suitable for very high heads compared to reciprocating

pump of same capacity. But, still in most cases, this is the only type of pump which is being

widely used for agricultural applications because of its practical suitability. The present testing

allows the students to understand and draw the operating characteristics at various heads, flow

rates and speeds, using different size of impellers.

Description:The present test rig is a self-contained unit operated on closed circuit basis. The pump,

electric AC motor, collecting-measuring tank set, control panel are mounted on rigid frame

work with anti-vibration mounts. The following are the provisions incorporated with the unit.

1. For conducting the experiments at three or two speeds using AC Motor.

2. The speed is indicated on digital RPM indicator.

3. To measure overall input power to the AC Motor using Energy meter.

4. The delivery and suction head are measured by using pressure & vacuum gauges.

5. For changing the Pressure (Delivery Head) and Vacuum (Suction Head) by operating thevalves.


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30

6. The flow rate is calculated using measuring (collecting) tank.

7. The overflow and butterfly valve are provided in collecting / measuring tank for

recirculation of water for closed circuit operation.

8. Change the belt to different speed positions and repeat the experiment.

9.

Repeat the experiment for the different Discharge.Operating Instructions:

All the necessary instrumentation along with its accessories is readily connected. It is

just enough to follow the instructions below:

1. Fill the sump tank with clean water.

2. Keep the delivery and suction valves open.

3. Connect the power cable to 1 ph, 220V, 15 Amps.

4. Select the required speed using step cone pulley arrangement.

5. Keep the delivery valve fully open after priming.

6.

Switch-ON the Mains so that the Mains-ON indicator glows. Now switch-ON themotor.

7. Note down the speed using digital RPM indicator.

8. Note down the pressure Gauge, Vacuum Gauge and time for number of revolutions of

Energy meter disc.

9.Operate the butterfly valve to note down the collecting tank reading against the known

time, and keep it open when the readings are not taken.

10.Repeat the experiment for different openings of the delivery valve (Pressure and Flow

rate), note down the readings as indicated in the tabular column.

11. Repeat the experiment for different speeds so that the pressure gauge reading are

shown and repeat the steps (4 & 9).

12. After the experiment is over, keep the delivery valve open and switch-OFF the mains.

13.Calculate the results using formulae given and tabulate it.

Draw the graphs of Head Vs Discharge

Formula to be Used:

1. Input power to the motor Pi (1)=36

kWPi (2)=

36 kW

Total input power = P1+ P2Where

N1 = Energy meter constant in rev / kWH (pump 1)

N2 = Energy meter constant in rev / kWH (pump 2)

T1 = Time taken for 10 rev. in the energy meter (pump 1)

T2 = Time taken for 10 rev. in the energy meter (pump 2)

2. Output power from the pump, P0=w Q kW

Where,

w = Specific weight of water in N/m3

Q = Discharge from the pump in m3/s

H = Total head of water in m


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31

3. Discharge from the pump, Q =A x

m3/s

Where,

A = Area of cross section of the collecting tank in m2

T = Time taken for x meter rise of water level in the collecting tank in seconds

4. Delivery Head, P = 9.8 w mWhere,

P = Pressure gauge reading in kgf / cm2

5. Suction head, G =G

13.6 mWhere,

G = Suction gauge reading in mm of mercury

6. Total head, H = P + G + X = ______________________ m

Where,

X = Vertical distance between suction gauge and delivery gauge.

7. Efficiency = 100 %


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32

Table: Multistage centrifugal pump

Size of collecting tank= Energy meter constant=

Sl.

No.

Pressure

gauge P

kg/cm2

Vacuum

Gauge G

mm of

Hg

Total head

H m of

water

Time for

10cm rise in

coll. tank t

sec.

Discharge

X 103

Q

Time for 10

rev.of

energy

meter

Input Input,

I

kW

Output,

O

kW

Efficiency

%

P1 P2 G1 G2T1sec

T2sec

I1kW

I2kW


33/65


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34

Ex. No. : CHARACTERISTICS CURVES OF SUBMERSIBLE PUMPDate :

Aim:To find the efficiency of the submersible pump.

Theory:

Pump:

The pump is a multistage centrifugal pump with radial impellers. Its a suitable for

vertical & horizontal installation for the pumping of clean water with a maximum permissible

sand content of 25 gm per cubic meter. The suction side is protected by a perforated strainer.

The pump bearings are water lubricated and screened against the ingress of sand. The motor

cable(s) run alongside the pump and are protected against mechanical damage by cable metallic

sheaths.

Motor;

The motor, a squirrel cage type, has water lubricated bearings and its windings are

intensively cooled by water surrounding it. The inside of the motor is protected against the

entry of well water sand by seal rings and sand guard. Pressure equalizing rubber diaphragm is

provided in the lower part of the motor. The axial thrust of the pump is taken up by a thrust

bearing. A single cable leads out of the motor through a cable packing box. The pump shaft

and motor shaft are rigidly connected by a coupling sleeve.

The pump is suited both for Horizontal & Vertical operation.

Direction of Rotation:

Let the pumping set run for a short time against a close discharge valve, in bothdirections of rotations. The direction of rotation is reserved by crossing over two phase leads

of the power supply. The discharge pressure should be read on the pressure gauge in both cases

and pressure will be higher in one case than in the other. The higher of the two pressures

corresponds to the direction of rotation.

Operating Instructions:


just enough to follow the instructions below:1. Fill the sump tank with clean water.

2. Keep the delivery valve open.

3. Connect the power cable to 1ph, 240V, and 5amps with earth connections.

4. Switch on the mains, so that the mains-ON indicator glows. Now, Switch-ON the pump.

5. Now, you will find the water starts flowing to the measuring tank.

6. Close the delivery slightly, so that the delivery pressure is readable.

7. Operate the delivery valve to note down the collecting tank reading against the known time,

& keep it open when the readings are not taken.

8. Note down the other readings as indicated in the tabular column.

9. Repeat the experiment for different openings of the delivery valve.

10.Tabulate the readings, after the experiment is over keep the delivery valve open.


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35


1. Basic Data / Constants

1 HP = 745 watts

1 kg/cm2 = 760mm of Hg (10m of water)

Density of water,w = 9810 N/m3Area of Collecting Tank = 0.126m2

2. Electrical Power As Indicated By Energy Meter:

VI

Pshaft = Hpelec = --------------------------- in KW.

1000

Where,

n = Number of revolutions of energy meter disc.

t = is the time taken by the Energy meter for n revolutions, in seconds.

3. Discharge Rate Q in m3/sec.

A x R 0.126 x R

Q = ----------- = --------------- in m3/sec.

1000 x T 1000 x T

Where, A = 0.126m2is the area of Collecting Tank.

R = the Rise of level water collected in mm.

T = time taken in seconds for R mm rise of water.

4. Total Head H in mtr.

H = 10 (Delivery Pressure)

= 10 (P) in m

Where, P is the pressure in kg/cm2.

5. Hydraulic Power (Delivered by the Pump)

WQH

Ppump=Hppump = -------- in KW.

1000

Where, W = 9810 N/m3.

Q = From Formulae-3.

H = From Formulae-4.

6. Pump Efficiency.Ppump

%pump = ------

Pshaft

GraphTotal Head Vs Discharge.


36/65

36

Result:

The performance characteristic of the submersible pump is studied and the efficiency is calculated %

TABLE OF CALCULATIONAREA OF COLLECTING TANK = 0.126 m2

Transmission efficiency= 60%

s.no

Delivery

Pressure

"P" inKg/cm2Voltage,V

volts

Current

in

ampsRise in

water levelh in mm Time for riseof water level

Total

Head"H"in m DischargeQa in m3/s

Power

output,P

pump inKW

Power

input to

motor

Hp elecin KW

Efficiency

in %


37/65

37

Ex. No. : CHARACTERISTICS CURVES OF RECIPROCATINGPUMPDate :

Aim:

To study the performance characteristics of a reciprocating pump and to determine the

characteristic with maximum efficiency.Apparatus Required:

1. Reciprocating pump

2. Meter scale

3. Stop watch

Theory:

In general a pump may be defined as a mechanical device which, when interposed in a


hydraulic energy, thus resulting in the flow of liquid from lower potential to higher

potential/Head.The pumps are of major concern to most engineers and technicians. The types of pump

vary in principle and design. The selection of the pump for any particular application is to be

done by understanding their characteristics. While the principle of operation of other pumps

is discussed elsewhere, in standard text books, the Reciprocating pump Falling under the

category of Positive Displacement Pumps, which is of our present concern, has plunger (Piston)

moves to and fro in a closed cylinder. The cylinder is connected to suction and delivery pipes

and are fitted with non-return valve allows the liquid only to enter the cylinder and the delivery

non-return valve allows the liquid only to escape out from the cylinder to the delivery line.

The piston is connected to a crank by means of connecting rod. As the crank is rotatedat uniform speed by prime mover, the plunger moves to and fro thus creating continuous flow

of liquid.

For more uniform flow, an air vessel is fitted before the suction valve, and after delivery

valve. This contributes for more uniform flow of liquid, and also saves energy input to the

pump from the prime mover. These pumps are available in Double Acting, Double Piston

(Duplex), Triplex, Qutraplex versions. The most commonly used one is Double Acting, single

cylinder Type, and is the one used in the present Test Rig. The medium of flow of water, and

the maximum speed normally less than 300 RPM. These pumps are used for High head and

Low Flow Rate application and find application in Automobile garages and finds application

in Automobile garages and multi-storied buildings where high head is required.

Description:The present test rig is a self-contained unit operated on closed circuit basis. The pump,

electric AC motor, collecting-measuring tank set, control panel are mounted on rigid frame

work with anti-vibration mounts. The following are the provisions incorporated with the unit.

1. To run the pump at different speeds using AC motor.

2. The speed is indicated on digital RPM indicator.

3. To measure overall input power to the AC Motor using energy meter.

4. To measure the delivery and suction heads using pressure and vacuum gauges separately.

(The delivery head pressure tapping is connected, upstream of delivery valve, and that ofthe suction tapping downstream of suction valve).


38/65

38

5. The flow rate is calculated using collecting tank and stop watch.

6. The overflow and butterfly valve are provided in collecting / measuring tank for

recirculation of water for closed circuit operation.

7. Change to different speed positions by changing belt provided in stepped cone pulley and

to repeat the experiment.8. Repeat the experiment for the different Discharge by operating the ball valve (delivery side)

provided.

Operating Instructions:


just enough to follow the instructions below:

1. Fill the sump tank with clean water.

2. Keep the delivery and suction valves open.

3. Connect the power cable to 1 ph, 220V, 16 Amps.

4. Switch-ON the Mains so that the Mains-ON indicator glows. Now switch-ON the

motor.5. Now adjust the speed using the stepped cone pulley arrangement.

6. Note down the speed using digital rpm indicator.

7. Note down the pressure Gauge, Vacuum Gauge readings.

8. Note down the time for n blinks of energy meter.

9. Operate the butterfly valve to note down the collecting tank reading against the known

time, and keep it open when the readings are not taken.

10.Repeat the experiment for different openings of the delivery valve (Pressure and Flow

rate), note down the readings as indicated in the tabular column.

11. Repeat the experiment for different speeds and repeat the steps (4 & 10).12. After the experiment is over, keep the delivery valve open and switch-OFF the mains.

13.Calculate the results using formulae given and tabulate it.

14.Draw the graphs of Head Vs Discharge.

Formula to be Used:

1. Input power to the motor Pi=36

N T kWWhere

N = Energy meter constant in rev / kWH

T = Time taken for 10 rev. in the energy meter

2. Output power from the pump, P0= w Q kWWhere,


Q = Discharge from the pump in m3/s

H = Total head of water in m

3. Discharge from the pump, Q =A x

m3/s

Where,

A = Area of cross section of the collecting tank in m2

T = Time taken for x meter rise of water level in the collecting tank in seconds

4. Delivery Head, P = 9.8 w m


39/65

39

Where,

P = Pressure gauge reading in kgf / cm2

5. Suction head, G =G

13.6 mWhere,

G = Suction gauge reading in mm of mercury6. Total head, H = P + G + X =______________________ m

Where,

X = Vertical distance between suction gauge and delivery gauge.

7. Efficiency = 100 %


40/65

40

VARIABLE SPEED RECIPROCATING PUMP

Energy meter constant : Vertical distance between suction gauge and pressure gauge, X=

Area of collecting tank :

S.

No.

Speed

(rpm)

Pressure

Gauge

Reading

(P)Kgf/cm2

Vacuum

gauge reading

(G)- mm

of mercury

Time taken

for x unit

rise in

water levelt in

seconds

Time

taken for

rev. in

energy-

meter Tin

seconds

Total

Head H

in metres

Discharge

from the

pump Qin m3/s

Input

power

P1 inkW

Output

power P0

in kW

Efficiency

in

%

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)


41/65

41

Model Calculation : (For Reading No_________)

Energy meter constant, N = rev/kWH

Area of cross section of the collecting tank, A = m2

Rise in water level in the collecting tank, x = m

Specific weight of water w = N/m

3

Pressure gauge reading, P = kgf / cm2

Time taken for x rise of water level in the collecting tank = sec

Time taken for___ energy meter blinks T = sec

Total head, H = P + G + X = m

Input power to the motor Pi=36

N T kW= kW

Discharge from the pump, Q =A x

m3/s

=m3/s

Output power from the pump, P0=w Q

kW

=kW

Efficiency = 100 = %Graphs:

1. Q vs H for various speeds

2. vs H

3. Pi vs H

Result:

The characteristics curves were drawn for the given variable speed reciprocating

pump and from the curves the following were obtained.

Max. efficiency of the pump = %Corresponding discharge from the pump = m3/s

Corresponding total head of water = m

Corresponding input power to the motor = kW


42/65

42

Ex. No. : CHARACTERISTICS CURVES OF GEAR OIL PUMPDate :

Aim:

To draw the characteristics curves of gear oil pump and also to determine efficiency of

given gear oil pump.Apparatus Required:

1. Gear oil pump setup

2. Meter scale

3. Stop watch

Theory:In general a pump may be defined as a mechanical device which, when interposed in a


hydraulic energy, thus resulting in the flow of liquid from lower potential to higher potential.

The pumps are of major concern to most engineers and technicians. The types of pump varyin principle and design. The selection of the pump for any particular applications is to be done

by understanding their characteristics. The most commonly used pumps for domestic,

agriculture and industries are; Centrifugal, Piston, Axial flow (stage pumps), Air jet,

Diaphragm and Turbine pumps. Most of these pumps fall into the main class, namely;

Rotodynamic, Reciprocating (positive displacement), Fluid (air) operated pumps.

While the principle of operation of other pumps is discussed elsewhere, the gear pump

which is of present concern falls into the category of Rotodynamic pumps. In this pump, the

liquid is made to rotate in a closed chamber. This pump consist of two identical inter meshing

spur pinions working in a fine clearance inside a casing. One of the pinions keyed to driving

shaft. Alternatively one of the pinions can be integral with the driving shaft. The other pinion

revolves idly. These pumps compared to reciprocating pumps are simple in construction, more

suitable for handling viscous, turbid (muddy) liquids, can be directly coupled to high speed

electric motors (without any speed reduction ) & easy to maintain. But, their hydraulic heads

at low flow rates is limited, and hence not suitable for very high heads compared to

reciprocating pump of same capacity. The present testing allows the students to understand and

draw the operating characteristics at various heads, flow rates and speeds.

Description:

The present test rig is a self-contained unit operated on closed circuit basis. The pump,

electric AC motor, collecting-measuring tank set, control panel are mounted on rigid framework with anti-vibration mounts. The following are the provisions incorporated with the unit.9. For conducting the experiments at three or two speeds using AC Motor.

10.The speed is indicated on digital RPM indicator with selector switch

11.To measure overall input power to the AC Motor using Energy meter.

12.The delivery and suction head are measured by using pressure & vacuum gauges.

13.For changing the Pressure (Delivery Head) and Vacuum (Suction Head) by operating the

valves.

14.The flow rate is calculated using measuring (collecting) tank.

15.The overflow and butterfly valve are provided in collecting / measuring tank forrecirculation of water for closed circuit operation.


43/65


44/65


45/65

45

Table: Gear Pump

S.

No

.

Pressu

re

gauge

readin

g P

kg/cm2

Vacuu

m

Gauge

readin

g V

in mm

of Hg

Total

Hea

d

H

m of

wate

r

Timefor 10

cm. rise

in

collecti

ng

Tank

t sec.

Dischar

ge from

the

pump Q

m3/sec.

Time for

10

revolutio

ns of

energy

meter

T sec.

Inp

ut

kW

Outp

ut

kW

Efficien

cy

%


46/65

46

Model Calculation : (For Reading No_________)

Energy meter constant, N = rev/kWH

Area of cross section of the collecting tank, A = m2

Vertical distance between two gauges (X)

Rise in water level in the collecting tank, x = mSpecific weight of water w = N/m3

Pressure gauge reading, P = kgf / cm2Time taken for x rise of water level in the collecting tank = sec

Time taken for___ energy meter blinks T = sec

Total head, H = HS+ HD+ X = m

Input power to the motor Pi=36

N T kW= kW

Discharge from the pump, Q =A x

m3/s

=m3/s

Output power from the pump, P0= w Q kW = kWEfficiency =

100 = %

Graph:

Discharge vs total head in m of oil

Input power vs total head

Percentage efficiency vs total head

RESULT:

The maximum efficiency of the gear pump =


47/65

47

Ex. No. : CHARACTERISTICS CURVES OF PELTON WHEELDate :

Aim:

To conduct load test on PELTON wheel turbine and to study the characteristics ofPELTON wheel turbine.

Apparatus Required:

1. Venturimeter

2. Stopwatch

3. Tachometer

4. Dead weight

Description:

The actual experimental facility supplied consists of a Centrifugal Pump Set, TurbineUnit, Sump Tank, Collecting, venturimeter arranged in such a way that the whole unit works

on recirculation water system. The Centrifugal Pump Set supplies the water from the sump tank

to the turbine through control valve which has the marking to meter the known quantity of

water. The water after passing through the Turbine units enters the collecting tanks. The water

then flows back to the sump tank through venturimeter for measurement of flow rate.

The loading of the turbine is achieved by rope brake drum connected to spring balance.

The provision for measurement of turbine speed (digital RPM indicator), Head on turbine

(pressure gauge) are built in on the control panel.

Theory:

A Turbine acts as a pump in reverse, to subtract energy from a fluid system. In impulse

turbine the fluid energy, first in the potential form, is next converted wholly into the kinetic

energy by means of one nozzle before striking the runner. The jet ensuring from the nozzle is

made to impinge on the runner tangentially as shown in the figure. A powerful jet issues out of

the nozzle, impinges on the buckets provided on the periphery of the nozzle. In practice these

buckets are usually spoon shaped, with a central ridge splitting the impinging jet into two

halves which are deflected backward. As there is no pressure variation in flow, the fluid partly

fills the buckets and the fluid remains in contact with the atmosphere. The nozzle is provided

with spear mechanism to control the quantity of the water. The actual energy transfer from jet

to wheel is by changing the momentum of the stream. The impact thus produced causes the

runner to rotate and hence produces mechanical power at the shaft.The main parts of a Pelton turbine are:

a) Spear Valve Mechanism:

In a pelton turbine the flow regulation is done with the help of a spear shaped needle valve.

It consists of a spear connected to a shaft with a hand wheel at its end.

By rotating the hand wheel the spear valve can be moved inside the nozzle axially. When

the spear is moved forward it reduces the floes area and hence flow through nozzle reduces,

similarly when it is moved backwards flow increases. Water flow can also be regulated by

the gate valve provided.

b) Runner with Buckets:

The runner consists of a circular disc with a number of evenly spaced double hemisphericalbuckets fixed along its periphery. The disc is mounted on a shaft. The buckets are divided


48/65

48

into two parts by a sharp splitter edge at the centre, which divided striking of the jet into

two equal parts. The buckets are so shaped that after flowing around its inner surface; the

water leaves it with a relative velocity almost opposite in direction to the original jet but

does not interface with the passage of water to the bucket preceding it during

rotation. There is notch cut at outer rim of each bucket only when it is almost normal to the

jet.c) Casing:

The casing of a Pelton turbine has no hydraulic function to perform. It is provided only to

prevent splashing and to lead the water to the tailrace. It is generally made up of stainless

steel and it is fabricated to form D section. Front part of the casing is made of acrylic.

Operation:

1) Connect the supply water pump-water unit to 3 ph, 440 V, 30A, electrical supply,

with neutral and earth connections and ensure the correct direction of the pump

motor unit.

2) Keep the Gate Valve and Sphere valve closed.3) Keep the Brake Drum loading at zero.

4) Press the green button of the supply pump starter. Now the pump picks-up the full

speed and becomes operational.

5) Slowly open the Sphere Valve so that the turbine rotor picks the speed and conduct

experiment on constant speed and constant head.

6) Note down the speed, load, and pressure gauge readings, tabulate the readings.

Formulae:

Discharge to the turbine Q = a1a22 g H m3/s

Where,

Cd = Coefficient of discharge of the venturimeter

a1 = Area of cross-section of pipe

a2 = Area of cross-section of throat

g Acceleration due to gravity in m/sec2

H = Drop in pressure head between the inlet and the throat of the venturimeter

= = 1 ~

= Specific gravity of the manometric liquid = Specific gravity of the liquid flowing through the pipeh1&

h2

= Manometer readings

Input power to the turbine Pi=w Q

kWWhere


Q = Discharge to the turbine in m3/s

H =Inlet pressure head in metres =

9.8 w m

Output power from the turbine P0= D N T 9.86 kW


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Where,

D = Effective diameter of the brake drum in m

N = Speed of the turbine in r.p.m

T = Net load on the turbine in kgf

T = (T1+ T0T2) kgf

T1 = Dead load on the loading arm in kgfT0 = Self-weight of the loading arm in kgf

T2 = Spring load in kgf

Efficiency = 100 %

Where,

P0 = Output power

Pi = Input power


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Table: Pelton Wheel

Diameter of Brake Drum=

Self wt. of the loading arm, T0=

Sl.

No

Manometer

readingsLoad in kgf Speed of

the

turbine

head

Drop in

pressure

head

Discharge

to the

turbine

Inlet

pressure

gauge

reading

(kg&cm2)

Inlet

pressure

head

Input

power

to the

turbine

Output

power

from the

turbine

Efficiency

of the

turbineh1 h2

DeadT1

SpringT2

NetT

cm m cm m N(rpm) H(m) Q(m3/s) P1 H(m) Pi(kW) Po(kW) (%)


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Effective diameter of brake drum D D = m

Level difference between the pressure gauge and the

vacuum gauge X

=m

Diameter of the inlet of the venturimeter, d1 = mDiameter of the throat of the venturimeter, d2= 0.6 d1 = m

Coefficient of discharge of the venturimeter Cd =Reading of the pressure gauges connected to the

venturimeter

P1 =kgf/cm2

P2 = kgf/cm2

Height of mercury column, in the right limb of the

manometer,

h1m

Height of mercury column, in the left limb of the

manometer,

h2m

Pressure gauge reading at the casing G = kgf/cm2

Vacuum gauge reading at the draft tube V = kgf/cm2

Dead added T1 = kgf

Spring load T2 = kgf

Acceleration due to gravity, g = m/s2

Self weight of the loading arm T0 = kgf

Speed of the turbine N = rpm

Specific weight of water w =


venturimeter H = 1 ~ mCross-section area of the pipe (a1) =

D4

=m2

Cross-section area of the throad (a2) =D

4 =

m2

Pressure drop between in the inlet of the venturimeter and

the throat section=

m

Discharge to the turbine Q =a1a22 g H

m3/s

=

m3/s

Inlet pressure head at the casing P = 9.8 w = m

Suction head at the draft tube G =G

=

Total Head H= P + G + X = =

Input power to the turbine P1=w Q kW

= kW

Net load T = (T1+ T0T2) = kg

Output power P0= D N T 9.8

6 == kW

Efficiency = 100

=

%


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Graphs to be drawn:

Efficiency vs speed

Result:

The characteristic curve, efficiency Vs speed, was drawn for the given Pelton wheel

turbine and from the curve

The maximum efficiency of the turbine, max= %

The speed corresponding to the maximum efficiency, Nnormal= rpm


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Ex. No. : CHARACTERISTICS CURVES OF FRANCIS TURBINEDate :

Aim:

To conduct load test on Francis turbine and to study the characteristics of Francisturbine.

Apparatus Required:

1. Stop watch

2. Tachometer

Description:

While the impulse turbine is discussed elsewhere in standard text books, Francis

turbine, the reaction type which is of present concern consists of main components such as

propeller (runner) scroll casing and draft tube. Between the scroll casing and the runner, the

water turns through right angle and passes through the runner and thus rotating the runner shaft.

When guide vane angels are varied, high efficiency can be maintained over wide range of

operating conditions.

The actual experimental facility supplied consists of a centrifugal pump set, turbine

unit, sump tank and Venturimeter arranged in such a way that the whole unit works on

recirculating water system. The centre fugal pump set supplies the water from the sump tank

to the turbine through gate valve. The water after passing through the turbine unit enters back

to the sump tank through the draft tube. The water then flows back to the sump tank through

the Venturimeter with pressure gauges for the measurement of flow rate.

The loading of the turbine is achieved A.C. Generator. The provision for; measurement

of brake force (voltmeter and ammeter), turbine speed (digital RPM indicator), head on theturbine (pressure gauge), head over the Venturimeter (pressure, vacuum gauge, 2 Nos) are

built-in on to the control panel.

The water enters a volute casing which completely surrounds the runner. The cross

sectional area of volute decreases along the fluid path in such a way as keep the fluid velocity

constant in magnitude. From the fluid passes between stationary guides vanes, mounted all

around the periphery of the runner. The function of these guide vanes is to direct the fluid on

to the runner at required angle. Each vane is pivoted and by a suitable mechanism all may be

turned is synchronism so as to alter the flow rate of the machine. In its passage through the

runner the fluid is deflected by the runner blades so that angular momentum is changed. Fromthe centre of the runner the fluid is turned to axial direction and flows to tail race via the draft

tube. The lower end of the draft tube must, under all conditions of operation, be submerged

below the level of water in the tail race. Only in this way it can be ensured that a turbine is full

of water.

Theory:

Francis turbine is an inward mixed flow reaction turbine named after the American

Engineer James B. Francis. In a Francis Turbine, water enters the runner at its outer periphery

and flows out axially at its centre. This arrangement provides a large discharge area with the

given diameter of the runner. A part of the net available energy of the water is converted into

kinetic energy and the rest of the major portion remains as pressure energy, as water enters the


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runner. The runner rotates due to reaction pressure caused by the pressure difference at the

runner entry and exit.

The main components of Francis Turbine are:

1. Scroll casing: Its a spiral shaped closed passage of gradually reducing cross-sectional area,

enclosing the runner. Its function is to distribute the flow uniformly along the periphery ofthe runner in such a way that the velocity remains constant at every point.

2. Guide Mechanism: There are two main functions of the guide mechanism (a) To regulate

the quantity of water supplied to the runner and (b) To adjust the direction of flow so that

there is minimum shock at the entrance to runner blades. It consists of a series of guide

vanes of aerofoil section fixed between to rings, in the form of a wheel known as guide

wheel. Each guide vane can be rotated about its pivot centre, which is connected to a

regulating ring by means of a link and lever. By operating the regulating ring the guide

vanes can be rotated, varying the width of the passage between adjacent vanes, thus altering

both the flow angle as well as the quantity of flow.

3. Runner: The runner consists of a series of curved vanes arranged evenly around the

circumference, in the annular space between two plates. It may be cast in one piece or made

of separate steel plates welded together. The runner vanes are so shaped that water enters

radially at the outer periphery and leaves it axially at the inner periphery. This change in

the direction of flow from radial to axial as it passes over the curved vanes changes the

angular momentum of the fluid thereby producing the torque, which rotates the runner. The

runner is keyed to shaft of the turbine.

4. Draft tube: It is a gradually expanding closed passage connecting the runner to the tailrace

(collecting tank). The lower end of the draft tube is always kept submerged in water. The

function of a draft tube is to convert the high kinetic energy of flow at runner exit intopressure energy, thus increasing the efficiency of the turbine. It also enables the turbine to

be installed above the tail race level without any loss of head.

Formula to be used:


m3/s

Where,

Cd = Coefficient of discharge of the venturimeter

a1 = Cross-section area of the inlet of the venturimeter in m2

a2 = Cross-section area of the throad of the venturimeter in m2

h = Venture head (or) the pressure head drop between the inlet and throat of the

venturimeter in m

h = 9.8 w m

P1 = Pressure intensity at the inlet of the venturimeter in kgf/cm2

P2 Pressure intensity at the throat of the venturimeter in kgf/cm2

w Specific weight of water in N/m3

g Acceleration due to gravity in m/sec

2

Input power to the turbine P1= w Q kW


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Where


Q = Discharge to the turbine in m3/s

Total Head, H = Total pressure head at the casing P (m) + suction head at the draft tube

G (m) + level difference between the pressure gauge and the vaccum

gauge X (m) .P = 9.8

w mG' = G

mP and G are the pressure gauge and Vacuum gauge readings in kgf/cm2

Output power from the turbine = D N T 9.8

6 kWWhere,

D = Effective diameter of the brake drum in m

N = Speed of the turbine in r.p.m

T = Net load in kgfT = (T1+ T0T2) kgf

T1 = Dead load in kgf

T0 = Self-weight of the hanger in kgf

T2 = Spring load in kgf

Efficiency = 100 %

Where,

P0 = Output power

Pi = Input power


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FRANCIS TURBINE

Self-weight of the hanger T0 =

Effective diameter of brake drum D =

The value of X =

S.

No.

Venturimeter

Pressure Gauge

readingsh =

(P1-P2)x104

w

in m

Pressure

gauge

reading

kgf/cm2

(P)

Inlet

pressure

head in

m (P)

Vacuum

gauge

reading,

G

Kgf/cm2

Suction

head in

m (G)

Total head

H=P+G+X

M

Speed

of the

turbine

in rpm

N

Load in kgfInput

power

to the

turbine

(P1)

kW

Output

power

to the

turbine

(P0)

kW

Efficiency

of the

turbine in

%

P1

Kgf/cm2

P2

Kgf/cm2

Dead

T1

Spring

T2

Net

T


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Effective diameter of brake drum D D = m

Level difference between the pressure gauge and the vacuum

gauge X

=m

Diameter of the inlet of the venturimeter, d1 = mDiameter of the throat of the venturimeter, d2= 0.6 d1 = m

Coefficient of discharge of the venturimeter Cd =Reading of the pressure gauges connected to the venturimeter P1 = kgf/cm2

P2 = kgf/cm2

Pressure gauge reading at the casing G = kgf/cm2

Vacuum gauge reading at the draft tube V = kgf/cm2

Load added T1 = kgf

Spring load T2 = kgf

Self weight of the hanger T0 = kgf

Speed of the turbine N = rpm

Specific weight of water w =

Cross-section area of the inlet of the venturimeter (a1) =D

4 =

m2

Cross-section area of the throat of the venturimeter (a2) =D

4 =

m2

Pressure drop between in the inlet of the venturimeter and the

throat section=

m


m3/s=

m3/s

Inlet pressure head at the casing P =9.8

w = m

Suction head at the draft tube G =G

=

Total Head H= P + G + X = =

Input power to the turbine P1=w Q kW

= kW

Net load T = (T1+ T0T2) = kg

Output power P0= D N T 9.8

6 = = kW

Efficiency = 100 = %Graphs:

With various values of and speed the characteristic curve can be drawn with the

speed along x-axis and efficiency along y-axis. From the curve, the maximum efficiency of the

turbine and the corresponding speed can be found out.

Result:

From the Graph,

The maximum efficiency of the turbine = %

Corresponding speed (Normal speed) of the turbine = rpm


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Ex. No. : CHARACTERISTICS CURVES OF KAPLAN TURBINEDate :

Aim:

To study the characteristics of a Kaplan turbine

Apparatus Required:

1. Venturimeter

2. Stopwatch

3. Tachometer

4. Dead weight

Theory:

Hydraulic (or Water) turbines are the machines which use the energy of water (Hydro-

Power) and convert it into mechanical energy. Thus the turbine becomes the prime mover to

run the electrical generators to produce the electricity, Viz., Hydro-electric power.The turbines are classified as Impulse & Reaction types. In impulse turbine, the head of

water is completely converted into a jet, which impulses the forces on the turbine. In reaction

turbine, it is the pressure of the following water, which rotates the runner of the turbine. Of

many types of turbine, the Pelton wheel, most commonly used, falls into the category of

turbines. While Francis & Kaplan falls in category of impulse reaction turbines.

Normally, Pelton wheel (impulse turbine) requires high heads & low discharge, while

the Francis & Kaplan (reaction turbines) require relatively low heads and high discharge. These

corresponding heads and discharges are difficult to create in laboratory size turbine from the

limitation of the pumps availability in the market. Nevertheless, at least the performancecharacteristics could be obtained within the limited facility available in the laboratories.

Further, understanding various elements associated with any particular turbine are possible with

this kind of facility.

Description:While the impulse turbine is discussed elsewhere in standard textbooks, Kaplan turbine,

the reaction type which is of present concern consists of main components such as propeller

(runner) scroll casing and draft tube. Between the scroll casing and the runner, the water turns

through right angle into axial direction and passes through the runner and thus rotating the

runner shaft. The runner has four blades which can be turned about their own axis so that the

angle inclination may be adjusted while the turbine in motion. When runner blade angles are

varied, high efficiency can be maintained over wide range of operating conditions. In the other

words even at parts loads, when a low discharge is following through the runner, a high

efficiency can be attained in case of Kaplan turbine, whereas this provision does not exist in

Francis and propeller turbines where, the runner blade angles are fixed and integral with hub.

The actual experimental facility supplied consists of a centrifugal pump set, turbine

unit, sump tank, Venturimeter arranged in such a way that the whole unit works on re

circulating water system. The centrifugal pump set supplies the water from the sump tank to

the turbine through gate valve which has the marking to the meter the known quantity of water.The water after passing through the turbine units enters the same tank through the draft tube.


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The water then flows back to the sump tank through the Venturimeter for the measurement of

flow rate.

The loading of the turbine is achieved by electrical AC generator connected to blub

bank. The provision for measurement electrical energy by energy meter, turbine speed (digital

RPM indicator), Head on the turbine (pressure gauge), are built-in on to the control panel.

Procedure:1. Connect the supply pump-motor unit to 3 ph., 440V, 30A, electrical supply, with neutral

and earth connections and ensure the correct direction of pump-motor unit.

2. Keep the gate value closed and Switch on the MCB.

3. Ensure that all the three indicators are glowing.

4. Keep the electrical load at zero, by keeping all switches in off position.

5. Keep the blade for the required position by adjustable wheel (1/4, , and full open).

6. Press the green button of the supply pump starter and then release.

7. Slowly, open the gate so that turbine rotor picks up the speed and attains maximum atparticular opening of the gate. Also ensure motor is running in correct direction.

8. Apply load by switching on each switch one at a time. (Or in a bunch)

9. Note down the Venturimeter pressures, time for 3 blinks in energy meter, speed, pressure

and vacuum on the meters at the control panel and tabulate results.

10.After completion of experiment remove the load by switching off all the electrical switches.

11.Close the gate & then switch OFF the supply water pump set.

12.Follow the procedure described below for taking down the reading for evaluating the

performance characteristics of the Kaplan turbine.

Formulae Used:

1. Electrical Power as indicated by Energy Meter:

n x 1000 x 60 x 60

BPelec = ------------------------ in KW.

3200 x t

BPshaft = BPelecx 0.7 in KW.

Where,

n = Number of blinks of energy meter disc.t = is the time taken by the Energy meter for n blinks, in seconds.

0.7 = Transmission Efficiency.

2. Discharge Rate, Q: Through Venturimeter:

Q = Cd (A1A2(2gHv))/(A12-A22) in m3/s

Where, Cd= Coefficient of discharge =0.91

A1= Inlet area of Venturimeter (150mm diameter) = 0.0177 m2

A2= Throat area of Venturimeter (75mm diameter) = 4.41810-3m2


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g = 9.81 m/s2

Hv= Head on Venturimeter, m=10h = 10 (PI-PT)

3. Hydraulic input to the turbine.

HIHYD= WQH in W

Where, W = 9810 N/m3

Q = Flow rate of water in m3/sec from formulae-1.

H = Head on turbine in m from formulae-3.

4. Head on the Turbine( H):

H = 10(PI+PV/760) Where, P = Pressure on the turbine = PI

PV= Vacuum at the turbine

5. Turbine Efficiency

( %tur):= BPSHAFT/ HIhyd100

6. Unit quantitiesunder unit head,

a) Unit speed, Nu = N/ (H)

b) Unit power, Pu = P/H3/2

c) Unit discharge, Qu = Q/ (H)

7. Specific speed:N (P)

NS =H5/4

Part load BPSHAFT

8. Percentage full load= 100

Max. Load BPSHAFT

GRAPHS:

A) For constant head characteristics

a. Turbine efficiency Vs Unit speed.

b.Unit power Vs Unit speed.

B) For constant speed characteristics:

a. Turbine efficiency Vs Percentage of full load.

b. Efficiency Vs. discharge.


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CONSTANT HEAD METHOD

Rotor

Vane

Position

Number

of bulbs

on

Voltmeter

Reading

in volts

Ammeter

Reading

in amps

Speed

in

rpm

Numb

er of

blinks

of

energymeter

disc, n

CE6461 - Fluid Mechanics and Machinery Laboratory.pdf

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