Venturi Meter And Orifice Plate Lab Report

By PRAJWAL M 18030141AE024 Fluid mechanics lab Experiment 01 Alliance college of engineering and design

VENTURI METER, ORIFICE PLATE AND NOZZLE METTER LAB REPORT

Venturi meter and orifice plate effects are two main and very important phenomenas in the fluid mechanic's subfield of mechanical engineering. In this post, the effect of venturi meter and orifice plate on the fluid flow will be discussed and completed work will be presented in the form of a report. Aim and Objectives Aim The aim of this experiment is to study the overall meter coefficient C of Venture meter and Orifice plate Objective The objectives of this experiment are 1. Understand the effect of a decrease in the area on the velocity and pressure of the flowing fluid 2. Understand the relationship between velocity and pressure of flowing fluid

3. Find the meter coefficient for venture meter and orifice plate Venture Meter According to Michael Reader-Harris (n.d), a Venture meter is an instrument used to study the flow of fluid when it passes through the converging section. There is an increase in the velocity and decrease in the pressure of the flowing fluid when the area available to flowing fluid decreases, this effect is called the venturi effect named after the physicist who first introduces this theory. Orifice Plate According to Michael Reader-Harris (n.d), an Orifice plate is an instrument used for three different applications one to measure the flow rate, second to restricting the flow and third is to reduce the pressure of the flowing fluid. It depends on the orifice plate associated calculation method that either mass flow rate or the volumetric flow rate is used for calculation. It uses the Bernoulli’s principle which shows the relationship between velocity and pressure of flowing fluid. When one increases then the second one decreases. According to DANIEL MEASUREMENT and control white papers, following are the different types of orifice plates The Thin Plate, Concentric Orifice Eccentric Orifice Plates Segmental Orifice Plates Quadrant Edge Plate Conic Edge Plate Nozzle meter: Flow-through nozzles a variant of internal flow with the additional effect of compressibility and the possible presence of shocks. Such situations occur in gas/vapor flows when there is a constriction in a passage across which there is a pressure difference e.g. flows through turbine/compressor blades, nozzles, rupture of a high-pressure vessel or tire etc. Compressible flow is the flow in which the density of fluid changes during flow. All real fluids are compressible to some extent and their density will change with change in pressure and temperature. a compressible flow fluid, such as air can be taken as incompressible with constant density if a change in temperature and duration are small and acceleration is low.In other words, if mach no. is small, compressible fluids can be treated as incompressible. However, the flow of gases/vapor through nozzles/turbines/compressor blades etc.at high velocity has high Mach number and their compressibility affects the drag coefficient. of bodies by the formation of shockwaves and discharge coefficient. (cd) of measuring devices such as orifice meters/pitot tubes etc

Theory According to Miller, R.W (1996) principle of continuity states that the decrease in the area of the flowing fluid will increase the velocity of the flowing fluid. With this increase in the velocity of the fluid, the fluid pressure will decrease to conserve the mechanical energy according to the law of conservation of energy. Flow rate is the product of the velocity of the flowing fluid with the area from which fluid is flowing. In venture meter, the area of the tube decreases gradually due to which the velocity increase to keep the flow rate constant. In the orifice plate, there is a sudden decrease in the area of the flow due to the restriction of the orifice plate. Due to this velocity will increase and pressure will decrease. According to Bernoulli’s equation P1+ 1/2×ρ×v1^2+ ρgh1=P2+ 1/2×ρ×v2^2+ ρgh2 As the change in height is zero so P1+ 1/2×ρ×v1^2= P2+ 1/2×ρ×v2^2 P2 - P1= 1/2×ρ×〖(v〗1^2- v2^2) As we know Q=AV Q=A √((2(P2-P1)/ρ)/(〖[A1/A2]〗^2-1)) As we know P= ρgh So Q= A1 √((2×g × ∆h)/(〖[A1/A2]〗^2-1))

In the above equation Q is the flow rate A1 is the area before convergence A2 area of convergence (throat) ∆h is the difference in height of heads across the convergence For real fluid, there will be a difference in the theoretical and measured values this may be due to the meter coefficient C Q= C ×A1 √((2×g × ∆h)/(〖[A1/A2]〗^2-1)) Apparatus Orifice Tube and Venture Meter Supply Hoses Measuring Tank Procedure To set up the orifice tube and venture meter apparatus two tubes were connected one on each of the outlet and inlet of the apparatus. The tube which was connected to the venture meter outlet was further connected to the measuring tank. To level the orifice meter and venturi tube apparatus, adjustable screws are provided at the apparatus. Apparatus was connected to the power source to run the motor for water supply. The bench valve and the control valve of the apparatus were open to let the water move into the tube and to remove all the air pockets. To raise the water level in the manometer tubes the control valve was closed gradually and when the height of the water level was enough high then the bench valve was gradually closed. With both valves were closed there was static water in the meter at a moderate pressure The flow rate of the water was recorded and the height of the water level was also recorded in all the tubes Difference between the heights of water level and the flow rate will change upon opening any one of the apparatus valves. The flow rate was calculated by the noticing the time required to fill the tank of a known weight and at the same time the level of the water in the manometer tubes was also recorded The same process is repeated for different flow rates

VENTRIMETER

SL no.

LPM

h

V the

V exp

Cd

e

1

20

0.026

0.000321

0.000315

0.981

40147.35

2

22

0.04

0.000398

0.000385

0.996

49056.24

3

24

0.051

0.00045

0.000417

0.915

53096.47

4

26

0.055

0.000467

0.000425

0.91

54205.3

5

28

0.062

0.000496

0.000447

0.903

56996.49

6

30

0.074

0.000542

0.000492

0.908

62719.09

7

32

0.082

0.00057

0.000531

0.939

67676.96

8

34

0.086

0.000584

0.000536

0.91

68263.25

chane in height (meter Hg)

volume flow rate (cubic meter per second)vs change in h 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 0

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

volume flow rate (cubic meter per second)

volume flow rate (cubic meter per second) volume flow rate experimental (cubic meter per second)

0.0006 0.0005 0.0004 0.0003 0.0002 0.0001 0 0

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

volume flow rate theoritical (cubic meter per second)

Cd vs Re 1.1 1

Cd

0.9 0.8 0.7 0.6 0.5 1

100

10000

Re

1000000

ORIFICE METER

SL no.

LPM

h

V the

V exp

Cd

Re

1

20

0.052

0.000454

0.0003244

0.714

41345.4

2

22

0.067

0.0005153

0.0003546

0.687

45194.45

3

24

0.089

0.0005939

0.00038

0.639

48431.72

4

26

0.108

0.0006543

0.0004189

0.64

53389.6

5

28

0.13

0.0007178

0.000431

0.6

54931.77

6

30

0.149

0.0007685

0.0004643

0.604

59175.92

7

32

0.157

0.0007888

0.0004655

0.59

59328.86

8

34

0.181

0.000847

0.0005047

0.595

64324.98

volume flow rate (cubic meter per second)vs change in h 0.2

chane in height (meter Hg)

0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04

0.02 0 0

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

0.0008

0.0009

volume flow rate (cubic meter per second)

Cd vs Re

0.8 0.7 0.6

Cd

0.5 0.4 0.3 0.2 0.1 0

volume flow rate experimental (cubic meter per second)

0

10000

20000

30000

Re

40000

50000

60000

70000

vthe vs vexp

0.0006 0.0005 0.0004 0.0003 0.0002 0.0001 0 0

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

volume flow rate theoritical (cubic meter per second)

0.0008

0.0009

NOZZLE METER

SL no.

LPM

h

V the

V exp

Cd

Re

1

20

0.091

0.000385

0.000317

0.825

50566.54

2

22

0.104

0.000411

0.00034

0.825

54087.4

3

24

0.112

0.000427

0.000346

0.809

55043.29

4

26

0.138

0.000474

0.000408

0.862

65048.27

5

28

0.16

0.00051

0.000412

0.808

65685.53

6

30

0.19

0.000556

0.000454

0.817

72344.89

7

32

0.21

0.000584

0.000478

0.818

76152.52

8

34

0.229

0.00061

0.00052

0.851

82795.95

Cd vs Re 1

Cd

0.8 0.6 0.4 0.2 0 0

10000

20000

30000

40000

50000

60000

70000

80000

90000

Re

V thero vs V exp 0.0006

V exp (m*3/s)

0.0005 0.0004 0.0003 0.0002 0.0001 0 0

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

V thero(m*3/s)

volume flow rate vs change in height chane in height (meter Hg)

0.3 0.25

0.2 0.15 0.1 0.05 0 0

0.0001

0.0002

0.0003

0.0004

0.0005

volume flow rate (cubic meter per second)

0.0006

0.0007

Discussion · 1. The curve shown in the graphs shows the linear relationship between flow rate and the difference in height

2. The result shows that with a decrease in the flow rate the value of the ∆h is also decreasing. So it can be said from the results that the difference in the height of the water level is directly proportional to the flow rate.

3. Change in the height of the water column of the venture meter is much less than the change in the height of the water column in the orifice plate this is because the difference in diameter of the areas of the orifice is much more than the venture meter. So we can say that the difference in height of the water column is directly proportional to the difference in the diameter of the area.

Conclusion An experiment was conducted to find the overall meter coefficient C in venture meter and orifice tube and results show that the flow rate and ∆h are directly proportional to each other and along with this ∆h and the ∆d are also directly proportional to each other. Both these thing are important as they are used to calculate the overall meter coefficient C