IRJET- Design and Performance Curve Generation by CFD Analysis of Centrifugal Pump

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 06 Issue: 05 | May 2019 www.irjet.net p-ISSN: 2395-0072
© 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 7378
Design and Performance Curve Generation by CFD Analysis of
Centrifugal Pump
Supriya Jadhav1, Vaibhav Ghodake2, Pavan Chipade3, Shubham Gaikwad4, Vikram Ghule5,
Nilesh Gaidhani6
1Supriya Jadhav, UG student, Dr. D Y Patil School of Engineering, Pune
2Vaibhav Ghodake, UG student, Dr. D Y Patil School of Engineering, Pune
3Pavan Chipade, UG student, Dr. D Y Patil School of Engineering, Pune
4Shubham Gaikwad, UG student, Dr. D Y Patil School of Engineering, Pune
5 vikram Ghule, Professor, Dept. of mechanical Engineering, Dr. D Y Patil School of Engineering, Pune
6Nilesh Gaidhani, Design Executive Indo Pump, Pune.
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Abstract - This work investigates a systematicnumerical
approach that employs Computational Fluid Dynamics
(CFD) to obtain performance curves of a backward-curved
centrifugal pump. Capacity curve obtained from the CFDS
analysis of centrifugal pump gives wide approach to
parameters such as cavitation and reverse flow. Semi open
impeller with single volute casing defines the path of flow.
This study is focused on effect varying discharge on its
performance parameters such as head, required powerand
efficiency. Head discharge relation will give ease of pump
selection. Mesh generation technique had discussed in the
project work for better CFD results.
Key Words: pump design, construction of blade, CFD
analysis, cavitation, performance curve.
1.INTRODUCTION
A pump is a mechanical device for moving a fluid from a
lower to a higher location or from lower to higher
pressure area. Performance of the ump may be affected
due to some geometrical and input parameters such as
blade angle, impellersize,dischargeandheadrequired.To
overcome the problem, designers often change the
geometry of the pump selection parameters. Specific
speed determines the geometry of the impellerandforces
in pump due to fluid flow whole design may be depend on
the performance curve generation which helps the
overcome the selection problem s and the required BEP.
While overcoming the losses the designed modification
can be done.
1.1 OBJECTIVES
1. Familiar approach to improve the design of
centrifugal pump and optimize its operational
parameters.
2. To study the centrifugal pump approaching
towards the radial flow pumps.
3. To evaluate pressure distribution at blade
and shroud region of the centrifugal pump.
4. To obtain the optimumpumpimpellerdesign
for effective suction of pump.
5. Plot performance curve of pump(H&Qcurve,
Efficiency vs. discharge vs. head curve).
6. To investigate the effective of impeller
geometry on pump performance.
7. To analyze the effect of variable dischargeon
cavitation pressure counters at impeller blade.
8. To check the performance of pump such as
efficiency, hydraulic power output wrt varying
discharge.
1.2 METHODOLOGY
Fig.1 flow of research

2. DESIGN AND DEVELOPMENT
2.1 Impeller
Pump have to carry 1000m3/hr with abrasive material
for the total head of 75 m from the storage tank at
atmospheric pressure. Specific gravity of fluid flowing
through the pump is 1.0. Pump having the speed for
impeller is 1450 rpm. The overall efficiency is assumed to
be 80% for the pump. While designing the pump, design
will tends towards the missed flow region. While
designing the pump modification in the design may vary
with respect to results.
Table -1 Dimensions of Impeller
Parameters Dimensions
Outside diameter ( 530 mm
Eye diameter ( 288 mm- 290
Vane inlet edge diameter ( 289mm
Outlet width 44 mm
Inlet width ( ) 81 mm
Diameter of shaft ( 59 mm
Vane inlet angle
Vane outlet angle (
Vane thickness ( t) 8 mm
Genration of impeller blade is mainly focused on the
blade curveture. Bl;ade curveture the pump performance
as it seprstes pressure regions. Blade curve is genratedby
multiple arc method.in multiple arc method, impeller is
divided into 6-8 curves. Final blade curve genrated is
replica of the curves in each section. Also impeller shroud
is designed with inlet and outlet width dimensions for
smooth flow of fluid.
Fig.2 Blade curve by multiple arc method
Fig.3 Developement of shroud
Fig.4 Developement of Impeller Blade and Shroud
2.2 Single Volute Casing

Volute of centrifugal pumpisgeneratedinsoftware CF
Turbo. CF turbo is popular tool for impeller and volute
generation due to Rapid design of hydraulic high-quality
pumps. Integration of established pump design theory.
Comfortable, reliable and user friendly Direct interfaces
for many CAE-software packages .Comprehensive and
detailed documentation manual.
Table-2 Input parameters for volute in CF Turbo
Required discharge 1000
Head required 75 m
Inner diameter 557 mm
Inner width of volute 90 mm
Outlet nozzle diameter 250nmm
Neck of volute
Fig.4 Generation Single volute in CF turbo
3. MODIFICATIONS OF STATOR COMPONENT:-
3.1 In-pipe And Elbow:
In pipe is used to guide the inlet water to theelbow.
Elbow is intermediate part between the Inpipe and
impeller shroud. Fig (2). Interference is created
between the Inpipe elbow and impeller in CFX pre.
3.2 Out-pipe
Function is to guide the flow of watercomingout
from the volute casting. This is required to minimize
the whirl component and to achieve better results.
Table-3 dimensions of auxiliary components
Element Diameter length
In Pipe 250 1000
Elbow 250-290 175
Out pipe 250 500
Interference is creates between the Inpipe and
Elbow is needed during CFD simulations, so the
dimensions must match with other component.
Outpipe coming out from the casing outlet is
increasing in cross-sectional area to create more head
at outlet by converting the kinetic energy into
pressure.
Fig.5 auxiliary component Inlet pipe, Elbow, Outlet
pipe
4. CFD ANALYSIS
As the impeller moves through the fluid, low-pressure
areas are formed because the fluid accelerates aroundthe
blades. The higher the fluid velocity, the lower becomes
the local pressure. If it falls below vapor pressure, the
fluid vaporizes and forms small bubbles of gas. These are
dragged to areas of higher pressure, where they collapse
and can cause very strong local shockwaves in the fluid,
which may even damage the blades. CFD helps to design
pumps with favorable cavitation behavior over a wide
operating range.
i) Preparation of surface model oftheimpellerandCasing
using software like PRO-E, CATIA, Uni-Graphics.
ii) Grid generation by using software like ANSYS-IECM.

iii) Application of boundary conditions usingsoftwarelike
CFX PRE.
iv) Solution and analysis of results using software like
ANSYS-CFX POST, Fluent.
v) Analysis of flow through hydraulic passages and
prediction of pump performance
characteristics by application of computational fluid
dynamic (CFD) techniques.
4.1. MESHING
The subdivision of the domain into no of smaller, non-
overlapping sub-domains: a grid (or mesh) of cells (or
control volumes or elements).For the meshingofimpeller
we used hexahedral mesh and for the volute we used
tetrahedral mesh.
Meshing plays main role in the outcome of the cfd
results. fine mesh is required near the region where more
chances of turbulence, cavitations such as impeller blade
wall, volute tongue and low pressure regions. Different
meshing techniques can be used to generate the mesh to
different parts of pump. Also the conditionofsurfacesand
quantity play main role in mesh quality. For the same
degree of polynomial the finite element space generated
by hexahedral elements is richerthanthespacegenerated
by tetrahedral elements. However the tetrahedral
elements are best to model complex geometry domain
with little distortion of mesh. Moreover, the
computational cost for assembling the global stiffness
matrix for tetrahedral elements is lower because there is
not necessary numerical integration.
Table-3 The mesh statistics is given bellow for each
component:-
Sr.
no
Component Mesh type Node
point
Element
No.
1 Impeller(Rot
ating
Domain)
Hexahedral 2308800 2438112
2 volute Tetrahedral 564769 1920449
3 In pipe Hexahedral 237600 244900
4 Out pipe Tetrahedral 34435 93026
5 Elbow Hexahedral 408988 398634
Fig.5 Blocking of impeller
Fig.6 Hexahedral mesh for single fluid
passage
Fig.7 Hexahedral mesh by blocking method

Fig.7 Tetrahedral Meshing of volute
Fig. 8 Meshing of In pipe, Out pipe and Elbow pipe
4.2 Boundary Conditions
Pre-processing consist of the input flow problem to cfd
program by means of operator friendly interface and
subsequent transformation of this input into a form
suitable for use by the solver. The user activities at the
preprocessing stage involve:
1. Selection of physical and chemical phenomenon
that need to be modelled.
2. Definition of fluid properties, fluid iswaterhence
select the water as fluid.
3. Specification of appropriate boundary condition
at cells which coincide with or touch the domain
boundary. We give boundary condition as the
flow rate of 1000 m3 /hr, and speed of 1450 rpm
as per our problem statement. Inlet discharge
conditions vary in 250, 500, 750, 1000,1250,
1500,1750 m3/hr.
4. Boundary conditions given to the pump are
depends upon the type input data and desired
results.
5. Input to impeller is given in mass flow rate
condition in kg / sec.
6. For rotating domain in pump, wall are consider
as the no slip wall and coordinate frame as the
rotating.
7. For stator domain, wall is considered as No slip
wall and wall roughness consider as smooth
wall.
Table-4 Boundary condition given to CFX Pre
Fluid Water (200 )
Inlet condition 101353 Pa
Mass flow inlet 277 Kg/sec
Domain motion ( Angular) -1450 RPM
Interference model General Connection
Interference type Fluid- Fluid
Mass and momentum
option for interference
Conservative
Interference flux
Analysis type Steady state
Turbulence model Shear stress transport
5. RESULTS
Visualization of the counters of pressure and velocity
variation are presented bellow. This contours give the
better understanding of low and high pressure areas
which are useful in modification in geometrical
parameters.
By solving different expressions in the cfx solvers, we
can get pump performance parameters such as power,
discharge , head obtained, and efficiency of pump on both
impeller and pump side.

Table-5 Result table at 1000 m3/hr
Mass flow rate 277 kg/sec
Total pressure inlet -799659 [Pa]
Total pressure outlet 17193.4 [Pa]
Volumetric efficiency 96.4123 %
Impeller efficiency 80.57 %
RPM 1450
Overall efficiency 75.37%
Total head output 83.51 m
Hydraulic power 237751 [W]
Total torque 1982.92 J
5.1 Pressure and velocity distribution for
different discharge
Fig.9 Pressure distribution in the pump volume at
1000 m3/hr
Fig.9 Pressure distribution over the blades at 1000
m3/hr
Fig.10 velocity distribution at sectional plane at
1000 m3/hr

Fig.11 Velocity distribution at 250 m3 /hr
Fig.12 Pressure distribution at 250 m3 /hr
Fig.14 Pressure distribution at 500 m3/hr
Fig.16 Velocity distribution at 750 m3/hr

Fig.22 Velocity distribution at 1750 m3/hr

Graph-1 Performance curve
3. CONCLUSIONS
The pump performance calculated by the cfd simulations
is well suitable for the given pump requirement. The
required head is 77m and designed head of impeller id
between 89 m. After simulation of pump, results
satisfactory with total head of 83 m , which Is above the
required head.
Observations obtained are bellow:-
1. As discharge increases, the power is increases in
constant proportion.
2. At low discharge condition( 250, 500 m3/hr),
pressure distribution at volute is dense and
increase rapidly. Cavitation is seems to be more
near blade inward curve side.
3. Pump efficiency is higher at 1000- 1200 m3/ hr
range. Pump performance is satisfactory at our
designed condition (1000 m3/ hr).
4. Whirl component is more at volute neck, means
back flow is observed at neck and impeller-
volute interface.
5. Efficiency of the pump likely to be reduced after
1500 m3/hr. Head also reduced sharply.
6. At lower discharge condition, pump is showing
vibration, uneven pressure and velocity
distribution.
REFERENCES
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[12] Mehta Mehul Pravinchandra Improving The Head
And Efficiency of A Pump 2016 IJEDR | Volume 4, Issue 2
[13] X Q Zheng et al Study on internal flowfieldsimulation
accuracy of centrifugal impellers based on different
meshing types IOP Conference Series: Earth and
Environmental Science

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