Fluid-1-Lab

Alexandria University Faculty of Engineering Mechanical Engineering Department

Fluid Mechanics Lab (SSP- 3rd term offshore)

Page 1 of 18

1- Calibration of Pressure Gauge Using Dead Weight Tester

Objective of the Experiment:

Calibration of a pressure gage using dead weight tester

Requirements:

1- Results (Tables + Graphs).

2- Draw the calibration curve.

3- Discussion of results and comments.

4- Conclusion.

Procedure:

1- Fill the interior of the apparatus with oil, and free it from air bubbles.

2- Fit the tested gauge in position.

3- Level the apparatus in a horizontal position.



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4- Table the reading of the tested gauge before putting the piston in place. This is the zero reading of

the gauge.

5- Close the valve of the tested gauge and put the piston in place. Put a load on the piston and use the

handle to reach the equilibrium position, Stake reading of gauge at equilibrium position.

6- Repeat, with increasing the load, use handle to retain equilibrium position.

7- Continue till you reach the maximum reading on the gauge then reduce the load gradually and take

readings in the unloading process.

8- Plot a curve between the actual pressure and the indicated pressure.

The actual pressure = (Load) / (Area of piston)

Indicated pressure = reading on the gauge.

Results:

Actual Pressure Indicated pressure (Kgf/cm2)

(Kgf/cm2) Loading Unloading Average

Zero



Page 3 of 18

2- Determination of the Centre of Pressure of a Plane Surface

Immersed In Water Using Hydrostatic Pressure Apparatus

Objective of Experiment:

To determine the position of the centre of pressure of a plane surface immersed in water and to

compare the experimental position with the theoretical position.

Experiment Setup:

Hydraulics Bench, Hydrostatic Pressure Apparatus.

Summary of Theory:

Any flat surface immersed in a liquid either partially or totally submerged is exposed to a force (F)

which is exerted by the liquid on this surface. This force equals the pressure at the centroid multiplied

by the area of the submerged surface.

Procedure:

1. Level the tank using the adjustable feet and spirit level.

2. Move the counterbalance mass until the balance arm is horizontal.

3. Close the drain cock and admit water until the level reaches the bottom edge of the quadrant.

4. Place a mass on the balance pan then add water slowly into the tank until the balance arm is

horizontal.



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5. Repeat the above for each increment of mass until the water level reaches the maximum

reading on the scale.

Readings to be taken:

Reading Number Mass on Balance, M ( gm ) Water level, hWater ( mm )

1

2

3

4

5

Results and Calculations:

hG

Pivot

hWater

C

G

ho

F

b

C

Gd

AreaYG

YC

Water Surface

Determination of the position of the center of pressure YC experimentally:

F = wL hG A

Where,

wL = Specific weight of liquid.

hG = Vertical distance from the liquid surface to the centroid of the



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submerged area.

A = Area of the submerged surface (A = b x d).

Taking moments about the pivot:

Mg * L = F * YC)A

Where,

YC)A = Actual vertical distance from the pivot to point C (center of

pressure).

L = Perpendicular distance between the pivot and the point of action

of the weights.

Calculations Table

Mg ( N ) L ( m) wL ( N/m3 ) hG ( m ) A ( m2 ) F ( N ) YC)A

Determination of the position of the centre of pressure YC theoretically:

CGY)Y GTh.C

oGG hhY

G

GG

hA

ICG



Page 6 of 18

12

dbI

3

GG

d x bA

Where,

YG = Vertical distance from the pivot to point G (centroid).

IGG = Second moment of area about horizontal axis passing through point

G and parallel to the liquid surface.

b = Width of submerged surface.

d = Length of submerged surface.

Calculations Table

hG ( m ) hO ( m ) YG ( m ) A ( m2 ) IGG CG YC)Th.

Plots:

Plot YC)A against YC)Th. for the partial and fully submerged cases.



Page 7 of 18

3- Calibration of Orifice Meter

Object of Experiment:

To find experimentally the coefficient of velocity, the coefficient of discharge and the coefficient of

contraction for a small orifice for the flow under constant head tank.

Equipment setup:

Summary of Theory:

vtx

y =2

2

1gt

gy

xvact

/2

ghvth 2

yh

x

yh

x

v

vC

th

actv

24

NOTE: x is the horizontal distance measured from the plane of the Vena Contracta. y is the distance

measured from the plane of the orifice.

Scale Paper

Clamp

Back

Board

Needle

Screw

Thumb Nut

with O-Ring

Adjustable

Overflow

Pipe

Locknut

Flexible Hose to

Sump Tank

Orifice Plate

Inlet Pipe

Adjustable

Feet Saffle 750

550

Head

Tank



Page 8 of 18

Qact = Volume (V) / Time (T)

gh2AQth

thactd QQC

Where A is the orifice area

Orifice diameter = 6 mm

vdc CCC /

Experiment procedure:

1. Connect the apparatus to the bench ensuring that the overflow pipe hose drains into the sump

tank. Level the apparatus by adjusting the feet, ensuring that the path of the jet coincides with

the row of measuring needles. Place a sheet of paper on the backboard, raise the needles to

clear the path of the water jet.

2. Raise the overflow pipe, open the flow control valve, admit water into the head tank. Adjust

the valve until the water is just spilling into the overflow. Record the head h on the scale.

Assess the position of the Vena-Contracta visually and note the distance from the orifice.

3. Adjust each of the needles in turn to determine the jet path, marking the position of the tops

of the needles on the sheet of paper on the backboard.

4. Measure the flow rate Q using the volumetric tank and stopwatch.

5. Repeat for different water levels h.

6. Calculate Cd, Cv and Cc at different tank heads

7. Plot Cd, Cv, and Cc against tank heads then find a specified values for each one of them from

the graph.



Page 9 of 18


Reading Head (h) Height (y) Distance (x) Velocity coefficient

No. mm mm mm Cv

1

2

3

4

5

6

Volume of water (V) Time (T) Flowrate (Q) Discharge

coefficient

Contraction

coefficient

lit sec lit / sec Cd Cc



Page 10 of 18

4- Calibration of Venturi-Meter


To investigate the validity of Bernoulli's Theorem as applied to the flow of water in a tapering circular

duct and calculate the discharge coefficient of a venture-meter.

Equipment Setup:

Hydraulics Bench, Bernoulli's Theorem Demonstration Apparatus, Stopwatch.

Summary of Theory:

areaThroat :A area,Inlet :A

2gAA

AA

51

512

5

2

1

51

HQth

5151 HHH

T

VVQ 12

act



Page 11 of 18

th

actd(v)

Q

QC

Procedure:

1. Take the reading of the manometers at section 1&5 to calculate the discharge coefficient for

five different flow rates.

Plots:

1. Venturi meter calibration curve.

2. Let 5151 HHH

be the x-axis and Cd the y-axis.


No. V1 (lit) V2 (lit) T (s) H1 (m) H5 (m)

1

2

3

4

5

No Qact (m3/s) Qth (m3/s) Cd

1

2

3

4

5



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5- Calibration Of Triangular Weir


Calibration of the triangular weir (Vee notch).

Equipment Setup:

Hydraulics Bench, Basic weir Apparatus (Vee notch), Height gauge, Stopwatch.

Summary of Theory:

2

5

2tan2

15

8HgQth

dC = Coefficient of discharge

2

= Half the enclosed angle of the vee

90

H = Head above bottom of notch



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T

VVQ 12

act

th

actd

Q

QC

Procedure:

1. Set up the equipment as shown in the diagram.

2. Set Vernier Height Gauge to a datum reading.

3. Position the gauge about half way between the notch plate and stilling baffle.

4. Adjust the feed water and the flow control valve.

Readings to be taken:

1. Take readings of volume and time to find the actual flow rate.

2. Take H reading from the height gauge.

Plots:

1. Weir calibration curve.

2. Let H be the x-axis and Cd the y-axis.


No. V1 V2 T H

lit lit s m

1

2

3

4

5



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No Qact (m3 /s) Qth (m3 /s) Cd

1

2

3

4

5



Page 15 of 18

6- Forced Vortex

Objectives of the Experiment:

The object of the experiment is to draw the surface pressure distribution on the bottom of a tank filled

with liquid subjected to forced vortex for different rotational velocities.

Experimental Procedures:

1. Turn on the motor switch.

2. Read the Piezometers zero reading (rotational speed =0.0 rpm).

3. Adjust the velocity regulator at certain rotational speed.

4. Wait for steady state (Piezometers readings = constant).

5. Read the reading of the 12 Piezometers.

6. Change the rotational speed.

7. Repeat the experiment for two rotational speed.

Observations:

No. at N1 (RPM) at N2 (RPM)

1

2

3

4

5

6

7

8

9

10

11

12

Pizometers zero reading:



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7- Secondary Losses in Bends and Fittings

Objectives of the Experiment:

The objectives of the experiment are to demonstrate the secondary losses associated with flow

through bends and fittings.

Experimental Procedures:

1. Close the regulation valve and start the centrifugal pump.

2. Open the valve partially.

3. Wait for steady flow (Peizometers readings = constant).

4. Read the differential readings of the Peizometers connected to the

mitre, the elbow, the short bend, the enlargement and the contraction.

5. Read the initial volume in the collection tank V1

6. Observe the time ( t ) to increase the collected volume to V2

7. Increase the valve opening

8. Repeat the experiment two times.

9. After recording all the required readings, close the valve gradually

then stop the centrifugal pump.

Note:

Pipe area: 301.7 mm2

Enlargement pipe diameter: 26.2 mm

Contraction pipe diameter: 19.48 mm



Page 17 of 18

Observations:

No 1 2

h

(cm)

V1

(lit.)

V2

(lit.)

t

(Sec.)

h

(cm)

V1

(lit.)

V2

(lit.)

t

(Sec.)

Mitre

Elbow

Short bend

Enlargement

contraction

Calculations:

velocityDownstream

velocityUpstream

Where

gg

g

g

:v

:v

:

)tEnlargemen(2

vv

2

)v-v(K =h

)nContractio(2

vK =h

)bendShort& ElbowMitre,(2

vK =h

t

VVQ

2

1

2

2

2

1

2

21

2

2

2

12act



Page 18 of 18

Results:

K 1 2 Average

Mitre

Elbow

Short bend

Enlargement

Contraction

Fluid-1-Lab

Documents

actual pressure

indicated pressure

calibration of pressure

centre of pressure

pressure gage

equilibrium position

horizontal position

tested gauge