Paper id 2820144

1. International Journal of Research in Advent Technology, Vol.2, No.8, August 2014
E-ISSN: 2321-9637
6
CFD Analysis and Comparison of Fluid Flow Through
A Single Hole And Multi Hole Orifice Plate
Malatesh Barki.1, Ganesha T.2, Dr. M. C. Math³
Department of Thermal Power Engineering1, 2, 3,
VTU PG Centre, Mysore/ VTU Belgaum Karnataka India1, 2, 3
Email: mechmlatesh@gmail.com1, ganeshtnaik88@gmail.com2,
mcmath1018@yahoo.com3
Abstract- Flow measurement is one of the most important tasks in many industries. Even today there does not
exist a universal flow measuring instrument in many flow applications. The fluid flow through a single hole
orifice plate and multi holes orifice plate were analyzed in this paper by using Computational Fluid Dynamics
(CFD). For analysis water is used as fluid and is allowed to pass through a pipe across the orifice plate. The
geometry of the orifice plate and the pipe section has made using CATIA V5 R20 and the model has meshed
using HYPER MESH 11.0, the flow characteristics are studied using ANSYS FLUENT 6.3.26. This paper also
presents the effect of orifice holes arrangement or distribution in a plate on the performance of flow
characteristics such as flow rate, pressure drop, velocity and turbulent intensity. The parameters used for
designing the orifice plate are non standard conditions. The analysis is carried out for four diameter ratio (d/D=
0.60, 0.30, 0.20, 0.15 for single hole, four, nine and sixteen holes respectively). The inner diameter of the pipe
used is 50 mm and the plate thickness used for analysis is 3 mm for all the plates. The simulation results shows
that multi holes orifice plate have better flow characteristics compare to single hole orifice plate for the same
area of departure.
Index Terms- Orifice plate, diameter ratio, CFD, pressure drop, turbulence intensity, multi hole orifice.
1. INTRODUCTION
Orifice meter is device used for the
measurement of flow in fluid delivery systems.
Orifice plate is an essential part an orifice meter when
installing in a pipe system [1]. There are different
types of orifice plate exist depending upon
applications, they are square edge, quadrant & conic
edge, integral, eccentric & segmental orifice plate.
The square edge orifice is used widely as restriction
for clean liquid, gases, and low velocity steams [2].
The orifice plate is widely used as throttling devices
in many industries such as oil wells, power generation
units, water treatment and distribution, chemical and
petrochemical industries. Orifice meter is widely
preferred in many flow applications due to ease in its
simplicity, low cost, easy to install or fabricate and
easy for maintenance [3]. If the if the t/d ratio is less
than 0.5, then it is thin orifice, otherwise it is a thick
orifice.[2].In this paper for the analysis the square
edge concentric type orifice plate is used. The inner
diameter of the pipe used is 50 mm and plate
thickness of 3 mm for all orifice plates.
1.1 Special features of heat orifice plate.
The orifice plate has good performances in a
certain operating parameter ranges there are,
(1) It can be operate up to a temperature of 800 0C.
(2) It can be operate up to a pressure of 400 bar.
(3) It is suitable for liquid, gas and steam flow
measurements. [2]
1.2 Draw backs of orifice plate
The major draw backs of orifice plates are,
(1) Maximum flow rate 4:1
(2) It is affected by upstream swirl.
(3) Large head loss. [2]
2. SELECTION OF ORIFICE PLATE
The orifice plate is widely used as a
restriction in many flow applications. There are
different types of orifice plates are there depends on
the applications and pipe size. In this paper the
analysis is carried out for an inner diameter of 50mm
hence the square edge concentric type orifice plate is
chosen. Due to ease in easy maintenance and low
cost and easy for manufacturing and installation it is
selected for analysis [7]. Fig 1 shows a standard
concentric type orifice plate.

2. International Journal of Research in Advent Technology, Vol.2, No.8, August 2014
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Fig.1. Standard concentric types orifice plate
3. COMPUTATIONAL MODELING AND
SIMULATION
For the simulations, Computational Fluid
Dynamics (CFD) is an effective tool to give an
effective results, it includes:
· Mathematical modeling
· Solution schemes
· Solver set up
3.1 Geometry modeling
The geometries of the orifice plates are
created by using the preprocessor tool as CATIA V5
R20. The data used for creating the geometries are
non standard conditions; the diameter ratio is selected
between the ranges 0.15 to 0.60 [2]. The inner
diameter of the pipe used is 50 mm; the length of the
pipe is 4D for both upstream and downstream side
and plate thickness of 3 mm for all the orifice plates.
Design parameters for orifice along with geometry are
shown from figure 2 (a) to (e). The figure 3 shows the
assembly of sixteen holes orifice plate in a pipe.
The arrangement of orifice holes in a orifice
plates are as follows:
· The orifice centre for all the plates are
located in concentric.
· The arrangements of orifice holes are
symmetrical as possible.
· The spacing between the all orifice holes in
plate is equal. [4]
(a) Single hole orifice having β=0.60, D=50
mm, d=30 mm.
(b) Four holes orifice plate having β=0.30, D=50
mm, d=15 mm
(c) Nine holes orifice plate β=0.20, D=50 mm,
d=10 mm
(d) Sixteen holes orifice plate β=0.15, D=50
mm, d=7.5 mm
(e) Nine holes square arrangement β=0.20,
D=50 mm, d=10 mm
Fig 2 (a) to (e) the geometric models for single and
multi hole orifice plates.
Fig 3 Sixteen holes orifice assembly.
3.2 Meshing
For the present work meshing is performed
by using HYPER MESH 11.0. Since the geometries
are in regular shape, the quadrilateral elements are
used for meshing. All the orifice plates surfaces and
also surface of the pipe are meshed by using 2D
quadrilateral elements. For discretization of all the
models 2D quadrilateral elements are used and the

3. International Journal of Research in Advent Technology, Vol.2, No.8, August 2014
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hexahedral mesh elements are used for 3D fluid
elements. Mesh size selected are coarse mesh for all
the orifice plates. For the all models the geometry is
divided in to 5 components. The meshed model for
one case that is for four holes orifice plate model in
2D and 3D discretization is shown in figure 4 and 5
respectively. The details of the discretization for
single and multi holes orifice models are shown in
table 1.
Table 1 Discretization details for different
orifice models.
Sl.
No
Orifice model nodes Cells Faces
1 Single hole 7872 6845 21470
2 Four holes 26724 26516 79676
3 Nine holes 33072 31149 95926
4 Sixteen holes 56202 59108 174450
5 Nine holes
(square
arrangement)
55514 51808 159056
The 2D and 3D Discretized meshed model for four
holes orifice are show in figure 4 and 5 respectively.
Fig.4. Discretized domain for four holes orifice model
with 2D quadrilateral elements
Fig.5. Discretized fluid domain for four orifice holes
model with 3D hexahedral mesh
4. SOLVER SET UP
The solver set up is very important in any of
the fluid flow problem; the solver setting indicates the
method and also a procedure for solving (analysis) the
problem. The flow analysis has studied using ANSYS
FLUENT (6.3.26) [8]
4.1 Turbulence Modeling
The turbulence model used for this work is
standard k-epsilon (2 eqn.) The 3D space pressure
based solver is used and implicit formulation is used
for solution scheme. Solution controls uses flow and
turbulence equations. The simple algorithm is used for
pressure velocity coupling and for discretization
second order scheme is used [9]. The convergence
criteria for all case studies are taken as 0.001.
4.2. Governing Equations
The governing equations of the flow are modified
according to the conditions of the simulated case.
Since the problem is assumed to be steady, time
dependent parameters are dropped from the equations.
The resulting equations are: [5]
· Conservation of mass :∇.( ρVr) =0. (1)
Momentum equations
· X-momentum:∇.(ρuVr)=-(∂p/∂x)+(∂τxx/∂x)
+(∂τyx/∂y) + (∂zx/∂z) (2)
· Y-momentum:∇.(ρvVr)=-(∂p/∂y)+(∂τxy/∂x)
+(∂zy/∂y) + (∂zx/∂z) +ρ g (3)
· Z-momentum:∇.(ρwVr)=-(∂p/∂z)+(∂τxz/∂x)
+ (∂yz/∂y) + (∂zz/∂z) +ρ g (4)
5. BOUNDARY CONDITIONS
The boundary conditions are the important
values for the mathematical model. The boundary
condition is applied to different zones. There are
different kinds of boundary conditions for the fluid
flow to enter and exit the domain. The boundary
condition is depending on type of fluid use for the
analysis. The fluid used for this analysis is
incompressible hence velocity inlet condition applies.
Inlet velocity profile was assumed, slip condition
assigned to all surfaces [6]. The boundary conditions
used for the analysis are listed in table 2.
Table 2 Boundary conditions used in CFD analysis
Sl.No. Quantities Condition/value
1 Working fluid Water
2 Gauge pressure Zero Pascal
3 Inlet velocity profile 1 m/sec
4 Slip No slip

4. International Journal of Research in Advent Technology, Vol.2, No.8, August 2014
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6. RESULTS AND DISCUSSION
The fig. 6 to 9 shows the pressure contours
and Fig. 11 to 15 shows the velocity contours
obtained for different orifice holes.
6.1 Pressure Contours.
Fig. 6 to 9 shows the cross section of
pressure contour plots for all orifice holes along the
length. .
Fig.6. pressure distribution for single hole orifice plate.
Fig.7. pressure distribution for four holes orificd plates.
Fig.8.pressure distribution for nine holes orifice in circular arrangement.

5. International Journal of Research in Advent Technology, Vol.2, No.8, August 2014
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Fig .9. Pressure contour for nine holes orifice in square arrangement.
Fig 10 pressure distribution for 16 holes orifice plate.
6.2 Velocity contours
The figures 11 to 15 shows the cross section
of velocity contour for different orifice geometries.
Fig.11. velocity contour for single hole orifice plate.

6. International Journal of Research in Advent Technology, Vol.2, No.8, August 2014
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Fig.12. velocity contour for four holes orifice plate.
Fig.13. velocity contours for nine holes orifice in circular arrangement.
Fig.14. velocity contour for nine holes orifice in square arrangement.
Fig.15. velocity contour for sixteen holes orifice plate

7. International Journal of Research in Advent Technology, Vol.2, No.8, August 2014
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6.3 Turbulence Intensity
The turbulence intensity contours for single
and multi holes orifice geometries are shown from fig
16 to 20
Fig.16. turbulence intensity for single hole orifice plate.
Fig.17. turbulence intensity for four holes orifice plate
Fig.18. turbulence intensity for nine holes orifice in circular arrangement.

8. International Journal of Research in Advent Technology, Vol.2, No.8, August 2014
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Fig.19. turbulence intensity for sixteen holes orifice plate.
Fig.20. turbulence intensity for nine holes orifice in square arrangement
Table 3 Summary of the results obtained for single hole and multi holes orifice
No. of
Orifice
holes
Holes
Arrangement
Volumetric
flow rate
(m3/s)
Pressure
drop (Pa)
Magnitude of
velocity (m/s)
Turbulence
intensity (%)
1 circular 0.1506404 2648.6936 3.84 91.2
4 circular 0.002 2573.5120 3.76 92.7
9 circular 0.001047624 2512.2705 3.49 94.0
16 circular -0.000139451 2588.1689 3.40 93.9
9 square -0.001390937 2544.8570 3.34 92.9
Table 3 shows the values of different
characteristics of fluid such as pressure drop, velocity
magnitude, volumetric flow rate, and turbulence
intensity for single and multi holes orifice for the
same area of departure are obtained from
computational analysis. By using the values from the
table 3 the different graphs are plotted. Thus the
different characteristics of fluid for the same area of
departure can be discussed.
6.4 volumetric flow rate
The volumetric flow rate for single
and multi holes orifice are shown in fig 21.The
volumetric flow rate is plotted against the number of
holes. It can be observed from the fig.21 the
volumetric flow rate is maximum for single hole

9. International Journal of Research in Advent Technology, Vol.2, No.8, August 2014
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orifice have a value of 0.150 m3/s. compare to multi
holes orifice plate. Comparing the holes arrangement
for 9 holes orifice plates, it is observed that 9 holes in
circular arrangement shows more volumetric rate
compare to square arrangement.
Fig .21. Volumetric flow rate for different orifice
holes
6.5 Pressure Drop
The pressure drop for single and multi holes
orifice plates are show in fig.22.
Fig 22. Pressure drop for single and multi holes
orifice plate.
It can be observed from fig 22 the net
pressure drop for single hole orifice is 2648.6936 Pa,
gradually decreases from four holes to sixteen holes,
it can be observed that the net pressure drop is
minimum at nine holes orifice in circular arrangement
it has value of 2512.2705 Pa. Further the pressure
drop is increases for sixteen holes orifice plate,
because the diameter ratio used is 0.15 for sixteen
holes orifice plate, further decrease in diameter ratio
the pressure drop increases. But comparing with
single hole orifice plate the net pressure drop is
decreases multi holes orifice for the same area of
departure. The effect of orifice hole arrangement
shows that the 9 holes orifice in circular arrangement
have a minimum pressure drop compare to square
arrangement.
6.6 Magnitude of Velocity
The velocity magnitude for single and multi
holes orifice plate are shown in fig .23.
Fig.23. velocity magnitude for single and multi holes
orifice plate
From the figure.23 it is observed that the
magnitude of velocity is maximum for single hole
plate compare to multi hole. For single hole orifice the
maximum velocity achieved, have a value 3.84 m/s,
when the number of holes increases the velocity
magnitude decreases. For single hole orifice the flow
concentrated at the center, for multi holes the flow
distributed over the all orifice holes hence velocity
decreases for multi holes orifice plate. Comparing the
holes arrangement for 9 holes orifice plate, it can be
observed that 9 holes in circular arrangements show
the more velocity have a value of 3.49 m/s compare to
square arrangement.
6.7 Turbulence intensity
Fig 24. Turbulence intensity for single and multi holes
orifice plate.
From the fig.24 it is observed that the
turbulence intensity increases for multi hole orifice
compare to single hole orifice. The turbulence
intensity is more for the nine holes orifice plate have a
value of 94%. Then it is decreased for sixteen holes.
By comparing the holes arrangement, the maximum

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intensity is achieved for 9 holes orifice plate with
circular arrangement compare to square arrangement.
7. CONCLUSION
Analysis is conducted on single hole orifice
plate and multihole orifice plate for single stage by
considering the same area of departure. Based on the
analyzed results, the conclusion can be summarized as
follows:
· For the same area of departure the single hole
orifice plate have more volumetric flow rate
compare to multi holes orifice, because the
velocity is more for single hole orifice plate.
· The pressure drop is minimum for multi holes
orifice plate compare to single hole. The
minimum pressure drop achieved for nine holes
circular arrangement orifice for the same area of
departure.
· The pressure recovery for a single hole orifice
plates needs much longer straight pipe it can be
seen from fig.6. Whereas multi holes orifice
needs shorter pipe for pressure recovery it can be
observed from fig.7 to 9.
· Multi holes orifice plate gives better performance
for short straight pipe applications, hence
effective savings in pipe material costs.
· The fluid flow distribution is more steady and
uniform for multi holes orifice plates compare to
single hole orifice, it can be observed from fig.16
to 20.
· The effect of holes arrangement on the fluid flow
characteristics for nine holes orifice plate, it can
be shows that the nine holes in circular
arrangement has better performance compare
with square arrangement.
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