87426770-Experiment-9

OBSERVATION AND CALCULATIONS: FOR WATER AT 30° C AND 1 ATM: DENSITY=996kg/m KINEMATIC VISCOSITY=0.802*10^-6 VISCOSITY=0.802*10^-6 DIAMETER 1=0.0183 m DIAMETER 2=0.0240m Re=ρDV/ʋ Re=ρDV/ʋ     

AREA: A = 3.142 D2/ 4 A1= 3.142 (0.0183)2/ 4 A1= 2.63 * 10-4 m2 A2=3.142(0.0240)2/4 A2=0.000452 m2

For enlargement and contraction: For enlargement and contraction change in area r esults in an additional pressure head which has been added to head loss readings for enlargement and contraction in the following tables: h’=(V22/2g)-(V12/2g) H1’=(0.380043379 ’=(0.3800433792/2*9.81)-(0.2209595962/2*9.81)= 0.00487308 H2’=(0.76008675 ’=(0.760086752/2*9.81)-( 0.4419191922/2*9.81)= 0.00019492 H3’=(0.95010844 ’=(0.950108442/2*9.81)-( 0.552398992/2*9.81)= 0.000304   

Fitting

Manometer 1

Manometer 2

Head Loss h

Volume

Time

h₁h₁-h₂

Total head loss Δh h+H1’

h₁

h₂

V

t

m

m

m

m

m³*E-3

sec

MITRE

2.42

2.18

0.24

0.24

1

10

ELBOW

2.8

2.63

0.17

0.17

1

10

SHORT BEND

3

2.88

0.12

0.12

1

10

ENLARGEMENT

3.06

3.18

-0.12

-0.1151269

1

10

CONTRACTION

3.1

3.02

0.08

0.08487308

1

10 Flow

GAUGE VALUE READING= 0 m Reynold’s No.

Flow Rate

Area

Velocity

Dynamic Head

K

Qt

A=PI/4*d²

V

V²/2g

Δh/(V²/2g)

m³/s

m²

m/s

m

440220.465

0.0001

0.0002631

0.3800433

0.019370203

12.39016

Turbulent

440220.465

0.0001

0.0002631

0.3800433

0.019370203

8.776366

Turbulent

440220.465

0.0001

0.0002631

0.3800433

0.019370203

6.195082

Turbulent

335668.104

0.0001

0.0004525

0.2209595

0.011261957

-10.6552

Turbulent

440220.465

0.0001

0.0002631

0.3800433

0.019370203

4.130054

Turbulent

Fitting

Manometer 1

Manometer 2

Total head loss

Head Loss h

Volume

Time

t sec 10

Δh

MITRE

h₁ m 1.99

h₂ m 1.46

h₁-h₂ m 0.53

m 0.53

V m³ *10^-3 2

ELBOW

2.75

2.38

0.37

0.37

2

10

SHORT BEND ENLARGEMENT

3.15 3.25

2.94 3.44

0.21 -0.19

0.21 -0.18980507

2 2

10 10

CONTRACTION

3.41

3.18

0.23

0.23019492

2

10

K

Flow

Reynold’s No.

Flow Rate

GAUGE VALUE READING= 0 m Dynamic Area Velocity Head

Q t m³

A=PI/4*d² m²

V m/s

V²/2g m

Δh/(V²/2g)

17274251.03 17274251.03 17274251.03

0.0002 0.0002 0.0002

0.000263128 0.000263128 0.000263128

0.760086758 0.760086758 0.760086758

0.038740406 0.038740406 0.038740406

13.68081 9.550752 5.420697

Turbulent Turbulent Turbulent

13171616.41 17274251.03

0.0002 0.0002

0.000452571 0.000263128

0.441919192 0.76008675

0.022523914 0.038740406

-8.43548 5.936954

Turbulent Turbulent

Fitting

Manometer 1

Manometer 2

Head Loss h

Total head loss

Volume

Time

V

t

Δh h₁

h₂

h₁-h₂

m

m

m

m

m³*10^-3

sec

MITRE

2.41

1.78

0.63

0.63

2.5

10

ELBOW

3.30

2.86

0.44

0.44

2.5

10

SHORT BEND

3.75

3.50

0.25

0.25

2.5

10

ENLARGEMENT

3.95

4.10

-0.15

-0.149695

2.5

10

CONTRACTION

4.05

3.76

0.29

0.290304

2.5

10 Flow

GAUGE VALVE READING=0 m Reynold’s No

Flow Rate

Area

Velocity

Dynamic Head

K

Q t=V/t

A=PI/4*d²

V=Q/A

V²/2g

Δh/(V²/2g)

m/s

m²

m/s

m

21592813.79

0.00025

0.000263128

0.950108448

0.048425507

13.00967

Turbulent

21592813.79

0.00025

0.000263128

0.950108448

0.048425507

9.08612

Turbulent

21592813.79

0.00025

0.000263128

0.950108448

0.048425507

5.16256

Turbulent

16464520.52

0.00025

0.000452571

0.55239899

0.028154892

-5.32767

Turbulent

21592813.79

0.00025

0.000263128

0.950108448

0.048425507

5.98857

Turbulent

EXERCISE B: GATE VALVE EXPERIMENT Rotations of gate valve

Pressure 1

Pressure 2

P₁

P₂

Bar

Bar

1

0.7

2 3 Flow Rate Qt

Δh of  water

Volume

Time

ΔP*10.2

V

t

Bar

m

m³

sec

1.1

0.4

4.08

0.004

10

1.1

1.62

0.52

5.304

0.003

10

1.62

2.25

0.63

6.426

0.002

10

Reynold’s number Re=ρDV/ʋ

Flow

K

34548502.07 25911376.55

Turbulent

34.6395978

Turbulent Turbulent

61.5815073 138.558391

Area

ΔP

A=PI/4*d²

Velocity V=Q T/A V

Dynamic Head V²/2g

m/s

m²

m/s

m

0.0004

0.00026313

1.520173517

0.117784277

0.0003 0.0002

0.00026313 0.00026313

1.140130138 0.760086758

0.066253656 0.029446069

17274251.03

Δh/(V²/2g)

1. DESCRIBE THE APPARATUS USED IN THIS EXPERIMENT. ANS. Energy Losses in Bends and Fittings Apparatus consists of:



Sudden Enlargement Sudden Contraction



Long Bend



Short Bend



Elbow Bend



Mitre Bend



Flow rate through the circuit is controlled by a flow control valve. Pressure tappings in the circuit are connected to a twelve bank manometer, which incorporates an air inlet/outlet valve in the top manifold. An air bleed screw facilitates connection to a hand pump. This enables the levels in the manometer bank to be adjusted to a convenient level to suit the system static pressure. A clamp which closes off the tappings to the mitre bend is introduced when experiments on the valve fitting are required. A differential pressure gauge gives a direct reading of losses through the gate valve. 2. WHAT ARE THE PRACTICAL USES OF STUDYING ENERGY LOSSES IN BEND? ANS. For any process, a certain range of flow rates is permitted for maximum efficiency, if the flow rate drops below that due to energy losses it disrupts the entire process and leads to loss o f expenditure and inefficiency. Hence the study of losses occurring in a particular fitting is necessary to obtain required efficiency.

3. FOR EXERCISE A, PLOT GRAPHS OF HEAD LOSS AGAINST DYNAMIC HEAD, AND K AGAINST VOLUME FLOW RATE(Q T). 

HEAD LOSS AGAINST DYNAMIC HEAD: TOTAL HEAD LOSS

DYANAMIC HEAD V2/2g

Δh

m

m

MITRE

ELBOW

SHORT BEND

CONTRACTION

0.019370203 0.038740406 0.048425507

0.24 0.53 0.63

0.17 0.37 0.44

0.12 0.21 0.25

0.084873 0.230194 0.290304

DYANAMIC HEAD V2/2g

TOTAL HEAD LOSS Δh

m

m ENLARGEMENT

0.011261957

-0.115126

0.022523914

-0.189805

0.028154892

-0.149695

HEAD LOSS AGAINST DYNAMIC HEAD 0.7 0.6 0.5 0.4 MITRE    S 0.3    S    O    L    D 0.2    A    E    H

ELBOW SHORT BEND CONTRACTION

0.1

ENLARGEMENT 0 0

0.01

0.02

0.03

-0.1 -0.2 -0.3

DYNAMIC HEAD

0.04

0.05

0.06



LOSS COEFFICIENT AGAINST VOLUME FLOW RATE FLOW RATE 3 m /sec

0.0001 0.0002 0.00025

LOSS COEFFICIENT K MITRE

ELBOW

SHORT BEND

ENLARGEMENT

12.3901645 13.6808067 13.0096728

8.77636655 9.55075183 9.08612066

6.19508227 5.42069699 5.16256856

-10.655342 -8.4354789 -5.3276709

CONTRACTION 4.13005485 5.93695384 5.98857953

LOSS COEFFICIENT AGAINST VOLUME FLOW RATE 15

10

5    T    N    E    I    C    I    F    F    E 0    O    C 0    S    S    O    L

MITRE ELBOW 0.00005

0.0001

0.00015

0.0002

0.0003

SHORT BEND ENLARGMENT CONTRACTION

-5

-10

-15

0.00025

VOLUME FLOW RATE

4. FOR EXERCISE B, PLOT GRAPHS OF EQUIVALENT HEAD LOSS AGAINST DYNAMIC HEAD, AND K AGAINST Q T. 

EQUIVALENT HEAD LOSS AGAINST DYNAMIC HEAD Head loss Δh

Dynamic head 2 v /2g

4.08

0.117784277

5.304

0.066253656

6.426

0.029446069

EQUIVALENT HEAD LOSS AGAINST DYNAMIC HEAD 0.14

0.12

0.1    D    A0.08    E    H    C    I    M    A    N0.06    Y    D

0.04

0.02

0 3

3.5

4

4.5

5

5.5

EQUIVALENT HEAD LOSS

6

6.5

7



LOSS CO-EFFICIENT “K” AGAINST Q T: Flow rate Q t 3 m /s

Loss coefficient K

0.0004

34.6395978

0.0003

80.0559595

0.0002

218.229466

LOSS CO-EFFICIENT “K” AGAINST Q T 250

200

   T    N    E    I 150    C    I    F    F    E      O    C    S    S    O100    L

50

0 0

0.00005 0.0001 0.00015 0.0002 0.00025 0.0003 0.00035 0.0004 0.00045

Flow rate Q t

5. COMMENT ON ANY RELATIONSHIP NOTICED. WHAT IS THE DEPENDENCE OF HEAD LOSSES ACROSS PIPE FITTINGS UPON VELOCITY? ANS. According to the observation table and gr aphs obtained we can establish that value of K decreases with increase in flow rate for some fittings. Besides this, the head loss in a particular fitting increases with increase in velocity. 6. EXAMINING THE REYNOLD’S NUMBER OBTAINED, ARE THE FLOWS LAMINAR OR TURBULENT? ANS. The Reynolds’ numbers are very high indicating TURBULENT FLOW. 7. IS IT JUSTIFIABLE TO TREAT THE LOSS CO-EFFICIENT AS CONSTANT FOR A GIVEN FITTING? ANS. Yes. It’s justifiable to assume loss-coefficient constant for a given fitting as it varies with velocity, flow rate and head losses. 8. IN EXERCISE B, HOW DOES THE LOSS CO-EFFICIENT FOR A GATE VALVE VARY WITH THE EXTENT OF OPENING THE VALVE? ANS. The loss coefficient for gate valve increases with decrease in the extent of opening of the valve according to our observation this is also in accordance with the formula for loss coefficient as the flow rate is decreased (the valve is closed) the velocity decrease thus the loss coefficient increases.