Testing And Performance Evaluation Of Butterfly Valve · Sachin K. Pisal ,Suresh M. Sawant ::...

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www.ijifr.com Copyright © IJIFR 2015

Research Paper

International Journal of Informative & Futuristic Research ISSN (Online): 2347-1697

Volume 2 Issue 9 May 2015

Abstract

This paper presents testing of butterfly valve for change in across pressure. The experimentation is carried out at 90°, 60° and 40° of valve disc by change in pressure drop, at this conditions discharge is measured. The study focuses on finding out flow characteristics and flow coefficient of 100mm butterfly valve. For higher performance it’s more and more essential to know the flow characteristic around the valve. Experimentation is conducted to observe the flow patterns and to measure valve flow coefficient when butterfly valve with various opening degrees. Furthermore, the results of experiment are compared with ANSYS FLOTRAN results.

1. Introduction

A butterfly valve is a type of flow control device that controls the flow of gas or liquid in a variety

of process. It consists of a metal circular disc with its pivot axes at right angles to the direction of

flow in the pipe, which when rotated on a shaft, seals against seats in the valve body. This valve

offers a rotary stem movement of 90º or less in a compact design [1]. The importance of butterfly

valves has been more and more increasing in the pipe system. And there are so many studies on the

characteristics, i.e. the flow coefficient, the torque coefficient, the pressure recovery factor and so

on. With the development of the Computational Fluid Dynamics (CFD), the approach of using the

technique of computational fluid dynamics has been substantially appreciated in mainstream

scientific research and in industrial engineering communities. By now, the CFD simulation by

Testing And Performance Evaluation

Of Butterfly Valve Paper ID IJIFR/ V2/ E9/ 010 Page No. 3129-3139 Subject Area

Automobile

Engineering

Key Words Pressure Drop, Flow Characteristic, Flow Coefficient, ANSYS FLOTRAN

Sachin K. Pisal 1

Assistant Professor

Department of Automobile Engineering

Sanjeevan Engineering and Technology Institute Kolhapur- Maharashtra

Suresh M. Sawant 2

Professor

Department of Mechanical Engineering

Rajarambapu Institute of Technology

Islampur - Maharashtra

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ISSN (Online): 2347-1697 International Journal of Informative & Futuristic Research (IJIFR)

Volume - 2, Issue - 9, May 2015 21st Edition, Page No: 3129-3139

Sachin K. Pisal ,Suresh M. Sawant :: Testing And Performance Evaluation Of Butterfly Valve

commercial code has been proved its feasibility to predict the flow characteristic. There have been

also many studies on valve using computational Fluid dynamics analysis [3].

The flow coefficient allows determining what size valve is required for a given application.

Pressure drop is a key criterion in valve selection. Increased pressure drop across a valve means

higher costs for pressurizing the fluid system [5]. Higher pressure drops decrease a valve's life

expectancy, and may even damage the rest of the fluid system. High pressure drops across open

valves should be avoided. A measure of a valve's potential pressure drop is the Cv (flow coefficient)

factor [4].

In past years extensive research work has been carried out in the area of CFD analysis. The

main advantage is to develop a model by using the commercial code ANSYS FLOTRAN, which

accurately represents the flow behaviour and provide a two and three-dimensional numerical

simulation of water around the butterfly valve and estimate the pressure drop, flow coefficient and

hydrodynamic torque coefficient. It is the first step towards improving valve design. [2].

2. Testing and result analysis

2.1 Flow coefficient (Cv): A constant Cv related to the geometry of a valve, for a given travel, that

can be used to establish flow capacity. It is the number of U.S. gallons per minute of 60ºF water that

will flow through a valve with a one pound per square inch pressure drop.

√

(2.1)

Where

Q = design flow rate (lit/s)

G = Specific gravity relative to water

= Allowable pressure drop across wide open valve in kg/cm2

2.2 Design of pipe diameter

We know

Maximum discharge of pump Q = 14 lit/s

By using continuity equation

VQ (2.2)

Where A = Area of pipe in „m‟

V = velocity of water in „m/s‟

VdQ

2

4 (2.3)

Assume velocity = 1.7 m/s

7.14

14 2

d

d = 0.102 m

d = 100 mm or 4 inch diameter pipe has been selected

2.3 Principal test rig arrangement:

Experimental set up for testing butterfly valve comprises electric motor of 5 H.P. whose

maximum discharge is 14 lit/s, 1850cm head and 2880 rpm. Amount of water is getting lifted from

water storage tank by means of electric motor which is passing through pipe of 100 mm diameter

whose length is 4900 mm. The butterfly valve is mounted at distance of 20D at upstream and 10D at

downstream. The pressure gauge at upstream of butterfly valve is at distance of 2D from valve

centerline and 6D at downstream is shown in figure 1.1. Where „D‟ is diameter of butterfly valve

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disc. Butterfly valve disc is operated manually by using hand wheel. We can set position of disc at

required angle by this hand wheel.

To control pressure drop across butterfly valve water bypass valve is provided as shown in

figure 1.2. By using this bypass valve it is possible to regulate discharge through valve up to certain

extent.

Figure 1.1 Photograph of Mountings of pressure gauges in pipeline with respect to position of butterfly valve.

Figure 1.2 Photograph of water bypass valve arrangement for changing pressure across valve.

Figure 1.3 Photograph of Discharge measurement method

Water Bypass

Butterfly valve

Reducer

Venturimeter

Pressure gauge

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y = 8.4507e0.0041x R² = 0.7026

6.0

7.0

8.0

9.0

10.0

11.0

12.0

13.0

15 30 45 60 75 90

Axis Title

dicharge anf angle

Expon. (dicharge anfangle)

Dsi

cha

rge

in

lit

/s

Discharge through venturimeter is calculated by

√

√( ) ( ) (2.4)

Where

Q= Discharge in „lit/s‟

a1 = Area of venturimeter at convergent section in „cm2‟

a2 = Area of venturimeter at throat section in „cm2‟

H = Pressure head in „m‟

21 PP

H

(2.5)

= Density of water in „kg/cm3‟

= Coefficient of discharge

2.4 Experimental result analysis

While doing experimental analysis parameters like pressure at upstream and downstream of

valve, Discharge at different positions of valve disc, disc angle and bypass system have been taken

into consideration for measurement.

2.4.1 Operating condition of butterfly valve

2.4.1.1 Change in pressure drop across butterfly valve

Now pressure drop across butterfly valve is changed by operating bypass valve,

simultaneously disc angle is changed and discharge through pipe is measured by venturimeter.

Area of Venturimetera1 = 7850cm² and a2 = 961.625cm²

Table 1.1Change in pressure drop across the butterfly valve and disc angle

θ (°)

(kg/cm²)

(kg/cm²)

ΔP

(kg/cm²)

(kg/cm²)

(kg/cm²)

ΔP

(kg/cm²)

H (cm) Q

(lit/s)

90 1.6 1.2 0.4 1.65 1.55 0.10 9.8100E+04 13.3456 89

60 1.9 1.13 0.77 1.58 1.53 0.050 4.9050E+04 9.4954 45

40 2.1 0.9 1.2 1 0.95 0.05 4.9050E+04 9.4157 36

Fig.1.4 shows characteristic curves of butterfly valve by changing pressure drop and disc angle.

From fig. 1.6 a) clear that as degree of disc opens the rate of flow that is discharge through pipe goes

on increasing

(a)

Degree of disc opening

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y = 0.9864x - 2.3705 R² = 0.9731

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0 15 30 45 60 75 90

Axis Title

Cv curve

Cv curve

Linear (Cv curve)

Flo

w c

oe

ffic

ien

t


y = -0.4812x + 6.1189 R² = 0.9492

0.3

0.8

1.3

1.8

2.3

2.8

5.0 7.0 9.0 11.0 13.0

DP and flow rate

Linear (DP and flow rate)P

ress

ure

dro

p k

g/

cm2

Discharge(Lit/s)

(b)

(c)

Figure 1.4 Characteristic curves of butterfly valve for change in pressure drop across the butterfly valve and disc

angle for 100 mm size. a) Degree of disc opening Vs Discharge b) Discharge Vs pressure drop across butterfly valve

c) Degree of disc opening Vs flow coefficient

When pressure drop across butterfly valve is high same time maximum discharge is obtained, it is

shown in fig. 1.6. When butterfly degree valve disc progress flow coefficient value increases.

2.5 The pressure and velocity distribution with varying disc angle and pressure in ANSYS

FLOTRAN

When valve disc is full open (at 90° valve disc angle) the discharge is maximum and value

of velocity is minimum due to more actual area of flow round the valve. As actual area of flow

decreases around the valve disc the value of velocity goes on increasing. The pressure and velocity

distribution with varying disc angle and pressure.

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Table 1.2 Simulation results of change in pressure drop across the butterfly valve and disc angle

Disc

angle(°)

Butterfly

valve pressure

P1 (kg/cm²)

Butterfly valve

pressure P2

(kg/cm²)

Butterfly valve

pressure drop (

P1-P2) (kg/cm²)

Velocity

in m/s

Discharge

in lit/s

Flow

Coefficient

( )

90 1.569 1.211 0.358 1.6 13.45 87

60 1.869 1.101 0.768 1.4 11.89 54

40 2.099 0.869 1.23 1.2 9.92 34

(a) (b)

(c) Figure1.5 a) Fluid velocity distribution b) Fluid velocity vector profile and c) Pressure distribution across 100mm

butterfly valve disc at 90°ofinlet velocity 1.7 m/s

(a) (b)

Low turbulence

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y = 0.0896x + 5.555 R² = 0.9752

6.0

7.0

8.0

9.0

10.0

11.0

12.0

13.0

15 25 35 45 55 65 75 85 95

Dis

cha

rge

in l

it/

s

Degree of disc Opening

(c)

Figure 1.6 a) Fluid velocity distribution b) Fluid velocity vector profile and c) Pressure distribution across 100mm

butterfly valve disc at 60° of inlet velocity 1.4 m/s

(a) (b)

(c)

Figure 1.7 a) Fluid velocity distribution b) Fluid velocity vector profile and c) Pressure distribution across 100mm

butterfly valve disc at 40° of inlet velocity 1.2m/s

(a)

High turbulence

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y = -0.1912x + 2.9314 R² = 0.9999

0.3

0.5

0.7

0.9

1.1

1.3

5 7 9 11 13

Pre

ssu

re d

rop

acr

oss

bu

tter

fly v

alv

e k

g/c

m2

Discharge in lit/s

y = 0.8804x + 14.231 R² = 0.9901

10

20

30

40

50

60

70

80

90

100

15 45 75

Flo

w c

oef

fici

ent


6.0

7.0

8.0

9.0

10.0

11.0

12.0

13.0

0 15 30 45 60 75 90

Dis

cha

rge

in l

it/s


Experimental

Simulation

Linear(Experimental)

Linear(Simulation)

(b)

(c)

Figure 1.8 Numerical characteristic curves of butterfly valve for change in pressure drop across the butterfly valve

and disc angle for100 mm size. a) Degree of disc opening Vs. Discharge b) Discharge Vs. pressure drop across

butterfly valve c) Degree of disc opening Vs. flow coefficient

(a)

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0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

5.0 7.0 9.0 11.0 13.0

Pre

ssu

re d

rop

cro

ss b

utt

erfl

y v

alv

e

kg

/cm

2

Discharge in lit/s

Experimental

Simulation


Linear(Simulation)

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

0 15 30 45 60 75 90

Flo

w c

oef

fici

ent


Experimental

Simulation


Linear(Simulation)

(b)

(c)

Figure 1.9 Comparison between experimental and simulation method at 40°, 60° and 90°position of valve disc a)

Degree disc of opening and discharge b) Pressure drop across butterfly valve and discharge c) Degree of disc

opening and flow coefficient by changing pressure and valve disc angle.

When pressure drop is constant the pressure drop error is more at 40 degree of valve disc, it may due

to erroneous method of simulation. Flow coefficient error at 60 degree of valve disc is also more due

to same reason. The value of flow coefficient matches at 40 degree and 90 degree of valve disc

position.

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3. Conclusion

The investigation of the flow characteristics through a butterfly valve under different opening

angles and for incompressible flow is studied by experimental and computational fluid dynamics

techniques. The flow field is visualized and the performance factors of the valve are calculated and

compared against experimental data.

The simulation is done in computational fluid dynamic software ANSYS FLOTRAN in 40, 60

and 90 degree of butterfly valve disc with changing pressure drop and disc angle, with changing

pressure drop and disc angle. It is found that more turbulent flow is occurred when valve disc is at

40 and 60 degree, because of more obstacle area to water flow. When valve is full open at 90 degree

it is less. The loss coefficient directly depends on position of valve disc. As degree of valve disc and

discharge increases flow coefficient value goes on increasing. So the flow coefficient is function of

valve disc shape. Flow coefficient is independent of the inlet velocity but it is dependent on the

valve size.

4. Abbreviations and Acronyms

V Flow velocity

D Nominal diameter of pipe

Cv Flow coefficient

Pressure drop

Density or specific mass of fluid

Flow rate

ΔPmax Maximum pressure drop

G Specific gravity relative to water

L Length of pipe

A Area of pipe

d Diameter of throat of venturimeter

Area of venturimeter at convergent section

Area of venturimeter at throat section

H Pressure head

Coefficient of discharge

θ Butterfly valve disc angle

Butterfly valve upstream pressure

Butterfly valve downstream pressure

ΔP Upstream and downstream pressure drop at valve

Upstream pressure of venturimeter

Downstream pressure of venturimeter

ΔP Upstream and downstream pressure drop at venturimeter

References

[1] Jun-Oh Kim, Seol-Min Yang, Seok-Heum Baek and Sangmo Kang, “structural Design Strategy of

Double-Eccentric Butterfly Valve using Topology Optimization Techniques” World Academy of

Science, Engineering and Technology 66, (2012)..

[2] Xue Guan Song, Lin Wang, Seok HeumBaek and Young Chul Park. “multidisciplinary optimization

of a butterfly valve”. ISA Transaction 48, pp 370-377, (2009).

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[3] C.K. Kim, J.Y. Yoon and M.S. Shin. “experimental study for flow characteristics and performance

evaluation of butterfly valves”, IOP Conf. Series: Earth and Environmental Science, pp. 1-7, (2010).

[4] Xue Guan Song and Young Chul Park.” numerical analysis of butterfly valve prediction of flow

coefficient and hydrodynamic torque coefficient”, Proceedings of the World Congress on

Engineering and Computer Science (2007).

[5] C.K. Kim, J.Y. Yoon and M.S. Shin. “experimental study for flow characteristics and performance

evaluation of butterfly valves”, IOP Conf. Series: Earth and Environmental Science, pp. 1-7, (2010).

Biographies

Sachin Pisal. Born on 21 May 1985 in Karad, India. Obtained Bachelor‟s degree

in Automobile Engineering and M.E. CAD/CAM/CAE from R.I.T. Sakharale,

Sangli, India. At present he is working as Asst. Professor in Automobile

engineering department at Sanjeevan engineering and Technology Institute

(S.E.T.I.) Panhala, Kolhapur India. His research interests include Fluid

Mechanics, Heat and mass transfer and computational fluid mechanics.. He is the

member and Faculty advisor of Society of Automotive Engineers (SAE).

Suresh Sawant obtained B.E. (Prod.) and M. E. (Mechanical) Shivaji University,

Kolhapur. Ph. D. (Mech.), National Institute of Technology, Warangal [A.P.]. He

is Professor at Rajarambapu Institute of Technology, Rajaramnagar, (Islampur).

He is Dean - Faculty of Engineering and Technology, Shivaji University,

Kolhapur. Member - Senate, Shivaji University, Kolhapur. Member - Academic

Council, Shivaji University, Kolhapur. Chairman - BOS (Automobile

Engineering), Shivaji University, Kolhapur.

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