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Technical Journal of Engineering and Applied Sciences
Available online at www.tjeas.com
©2017 TJEAS Journal-2017-7-1/28-35
ISSN 2051-0853 ©2017 TJEAS
Slurry flow simulation in 1.5/1 AH Warman Pump
Fardin salmaniyeh1*, Hossien Badragheh2, Hossien Beheshti Amiri3
1*. Iran Mineral Processing Research Center, Karaj, Iran
2. Iran Mineral Processing Research Center, Karaj, Iran
3. Amirkabir University of Technology ,Tehran,Iran
*Corresponding author email: [email protected]
ABSTRACT: Different types of pumps are used for pumping sluries, such as positive displacement
pump and some special ones like ejectors. Although centrifugal pumps are the most practical slurry
pumps. Seveier abrasivity is the graetest aspect of these pumps. Short life time, poor performance,
low efficiency are the defects that wear induced. A large number of studies have been focuse on
detecting the effective parameters on wear conditions and undersatnding the confronting solutions
for this harmfull phenomenon. Hence, the pump flow simulation is a practical method, for studying
and analyzing the pump performance. This paper shows a numerical simulation of the tree-
dimensional fluid flow inside a centrifugal pump. The pump is a 1.5/1 AH Warman pump taht
modeled in commercial Solidworks software. Then the 3D-CFD simulation of the impeller and volute
of a centrifugal slurry pump has been performed using ANSYS-CFX code. In following, the
performance curve produced by extracting the flow parameters. In order, to verify the simulation,
a Performance tests are carried out. Simulation results in the form of characteristic curves were
compared with available experimental data, and an acceptable agreement was obtained. And also
the results shows the confirmation by performance curves that provided by the pump manufacturer.
In addition, the exact amount of NPSHreq determined by simulation method and by calculating
equation. The main achievement of these study is to verify the analyzing software for simulating the
slurry flow in pumps. The objective of this study is to show through verification and validation that
simulation tools can be used to predict realistic beaver of slurry flow in centrifugal pump.
Keywords: slurry pump; numerical simulation; Flow rate characteristic; cavitation
INTRODUCTION
Compared with many mineral processing processes slurry pumps do not have a sophisticated design.
In fact, despite their simple design, but few machines can be found in mineral processes that can work in Hard
and tough conditions such as slurry pumps. The Permanent and continuous operation of this machine, under
unconventional flow conditions, requires reliable mechanical design in all pump details, because these pumps
are almost an integral part of the process of processing 1
slurry pumps are used extensively in the mineral industry, especially in the Industrialists that use the
separation system. These systems usually move a large amount of slurry in their processes. Other uses of
slurry pumps include Fertilizer production factories, Arid regeneration projects, disposal of fossil fuels of power
stations, mining and transfer of coal and minerals over long distances. Also, increasing public attention to the
environment and energy consumption has expanded the use of slurry pumps [2]
Theory of the article
The Warman pump, 1.5 size to 1 AH model that is one of the most utilizable slurry pumps for modeling
and performing practical tests is used. One of the reasons for choosing this pump was its inability to work
before the research. Because the wear and tear of the parts reduces the accuracy of the modeling and then
distorts the simulation results
As well as the availability of the pump test equipment (flowmeter and Barometer) up to 90 cubic meters
per hour (25 liters per second) in the pilot section of the research center, allowing the pump to be tested
practically
Previously, researchers have been using analytical software to predict the behavior of the sluries, the
process of wearing parts and its effects on the performance of the pumps [3], [4 [].For this purpose, at first,
three main parts of the pump segment, including the spiral, Impeller and the rear plate of the Measuring
Tech J Engin & App Sci., 7 (1): 28-35, 2017
29
chamber, and then in the Solidworks
software were three-dimensional modeling. In the following, the assumed
model is transmitted to the Ansys-CFX
software and is carefully meshed in the grid segment
Then the settings for Parameters of pump flow simulation are recorded. One of the most important
evaluation parameters is the type of fluid, boundary conditions, the second computation and the type of two-
phase model. In Fig. 1, the parts of the pump are displayed
Figure 1: Pump (4) with Impeller (1), rear frame (2) and spiral
In the modeling, the smallest detail has been considered, the most important of which is to consider the
lags, the geometry of the Geometry of Impeller Rear Blades, fillet edges, the alignment of common member
boundaries, and other parameters
Fig. 2, the cut-off view of the three-dimensional model of the pump is shown
In numerical methods, to determine the flow behavior, the fluid environment (space between chamber
and the impeller) must be grid. Selecting the type of grid and dividing the resolved area to the smaller areas to
produce a better grid has a particular importance
Figure 2: Cut-off view of the three-dimensional pump model
Boundary layer gridding has been used to increase the accuracy of the solver near the walls and fine
modeling of the turbulent flow. In Figure 3, the used gridding in this study is presented
1
-Solidworks
2
-Ansys-CFX
Tech J Engin & App Sci., 7 (1): 28-35, 2017
30
Figure 3: Gridding the fluid space in the impeller
Fluid flow settings now need to be considered. For this purpose, the considered fluid is water. For the
Impeller boundary conditions, a Rotational environment
at a speed of 1,900 rpm and for a Stationary
environment
is defined.
It is also the K_ω model
to simulate the Turbulence effects is considered. For energy equations, the
total energy model
is used to solve energy equations in the form of couplings with other equations. The
boundary condition at the input, the static pressure value, and at the outlet, the amount of flow is considered
For rotational and Stationary range connection of Interface conditions
and Boundary condition of the
wall also from the No Slip model
has been used. Upon completion of simulations, the solver will continue to
achieve convergence, flow equations and thermodynamics. Now The desired information, such as pressure
and speed contours is extracted
CONCLUSION AND SUGGESTIONS
Initially, the most important flow and thermodynamic contours are studied. These contours in different flows and
in a certain range of pumps is provided, which include the pressure contour and flow rate. It should be noted
that all contours are made from the middle plate of the fluid space
Pressure contour
In the following, four of the simulation outputs are displayed for different flows
Figure 4: Changes in the flow pressure inside the Pump with 2 liters of flow per second
3
- Rotational
4
- Stationary
5
- K_ω
6
- Total Energy
7
-Interface
8
- No Slip
Tech J Engin & App Sci., 7 (1): 28-35, 2017
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As shown in Figures 4 to 7, the minimum fluid pressure is always in the Impeller Eye, and by moving
away from the center and reach to the edges of the Impeller, the pressure gradually increases and its maximum
value is in the spiral output nozzle
The flow increases process, leads to the average decrease in fluid pressure in the chamber. As in the
high flow, the difference in fluid pressure at the inlet and outlet is not significant Notable point, is the high fluid
pressure in the spiral tenon, which in all cases is more than other points. Therefore, the wear rate of this spiral
region is very high in the slurry pump, and it is recommended that the thickness of the spiral tenon is
considered more than other spiral sections
Figure 5: Changes in the flow pressure inside the Pump with 4 liters of flow per second
Figure 6: Changes in the flow pressure inside the Pump with 6 liters of flow per second
Figure 7: Changes in the flow pressure inside the Pump with 8 liters of flow per second
Tech J Engin & App Sci., 7 (1): 28-35, 2017
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Speed Contour
Contour of Fluid velocity changes in the chamber in Figures 8 to 10 are shown for the three specified flow rates
Figure 8: Changes in the flow pressure inside the Pump with 2 liters of flow per second
Other than the first mode, that the pump flow rate is very low, in other cases, the flow of fluid inside the
chamber without any vortex or fluid separation passes through the blades profile. Also, according to
Compatibility of the velocity and pressure contours, the velocity of the fluid increases gradually from the edge of
the blades to the end of the blade. The maximum flow velocity is generated in the edges of the blades
Figure 9: Changes in the flow pressure inside the Pump with 4 liters of flow per second
Figure 10: Changes in the flow pressure inside the Pump with 8 liters of flow per second
In low flows, there is a high probability of flow return. As seen in Fig. 8, the velocity in the output nozzle
is very low, and therefore, the accumulation of fluid in the spinal gorge has a temporary and regional increase
of Flow Basically, slurry pumps work at low speeds, because the wear rate is directly related to the speed.
Hence, at the edge of the blades, which have a high fluid velocity, they are subject to severe wear. However,
Tech J Engin & App Sci., 7 (1): 28-35, 2017
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with the same argument, cannot concluded that least abrasion is in the Impeller Eye area, because the wear
process in the Impeller Eye is of a different kind
Extract and compare the characteristic curve
Of numerical simulation capabilities, is access to all functional data such as the characteristic curve of
the pump. Therefore, the amount of pump head in different flow is calculated and based on that the curve of the
head is plotted in terms of pump flow. On the other hand, in order to validate the simulation results, the
performance curve of the pump is based on the practical test is provided, which is shown in (Fig. 11). The
difference between the numerical and experimental results in average is 6%.
One of the reasons for this difference is the drop of the shaft torque in the Seals chamber, because the graphite
strips act as a brake in practice. Therefore, the torque of the Impeller in practice is less than its real value. The
leakage of the pump and pressure reducing elements such as valves and pressure gauges are other reasons
for the difference between the obtained values. Since frictional losses are directly related to flows, so the
amount of drop has increased with increasing flow
Figure 11: Comparison of the pump Functional curve by numerical and experimental methods
From the obtained curves comparison with the characteristic curve of Warman [8] company, in (Fig.
12), the accuracy of the practical test and the results of numerical simulation is well observed. As expected, the
results of the numerical simulation, with the presented characteristics by the company is more in line.
Figure 12: Functional pump curve
Determine minimum positive suction pressure
Another advantage of numerical methods is the ability to calculate NPSHreq for the pump. For this
purpose, very precise adjustments should be made to simulate Two-phase steam-liquid flow, so that it can
simulate the phenomenon of cavitation.
In this regard, the slurry flow is simulated in five states with different input pressures, that its details are
given in (Table 1). The amount of Flow rate and pump round in all states are considered constant, and with the
Tech J Engin & App Sci., 7 (1): 28-35, 2017
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gradual reduction of the inlet pressure, the possibility of air bubbles creation increases. This trend continues to
drop by 3% of head
The Frequency percentage of vapor phase in the space between fluid blades in simulated cases of E,
C, A rows respectively in Figures 13 to 15 are shown. By decreasing the inlet pressure from 0.3 to 0.2 bar in C
mode, water vapor bubbles are created in the Impeller Eye and begin to grow slowly
Figure 13: How to change the steam phase in the pump Eye in position A
Figure 14: How to change the steam phase in the pump Eye in position C
As seen in the speed contours, the velocity of the fluid in the eye has the highest value, and therefore
the first signs of cavitation appear in the Impeller Eye. In the following, with a further reduction in the inlet
pressure, the Frequency percentage of the vapor phase in the Impeller increases and extends to the mid-length
of the blades
Figure 15: How to change the steam phase in the pump Eye in position E. According to Figures 14 and 15, the minimum
positive suction pressure of this pump should be very close to the pump condition in position B. But we use the
computational method to find the exact value of this parameter. For this purpose, just calculate this parameter for the A to F
runs, according to equation (1) is calculated. The obtained values in Table 1 are listed
1𝐍𝐏𝐒𝐇𝐑 = 𝐏𝟎 𝐦𝐢𝐧
𝛒𝐠 +𝐕𝟎𝟐
𝟐𝐠 −𝐏𝐯
𝛒𝐠
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Table 1
Run
Name
Round
(rpm)
Row
(L/s)
Pressure
bar(inlet)
Amount of
suction
head (m)
Pump
head
(m)
A
1900
6
0.30
4.9913
31.33
B
1900
6
0.25
4.4814
31.33
C
1900
6
0.20
3.9715
30.72
D
1900
6
0.15
3.4616
29.63
E
1900
6
0.1
2.951
28.1
The curve of the head pump variation according to the suction head is shown in Fig. 16 on the basis of
the above table information. According to the standard, the minimum pump head is equal to the inlet pressure
at points where the head of the pump decreases by 3% of the initial head. Therefore, the NPSHreq amount is
equal to 3.85 meters. As shown in the NPSH diagram (Fig. 16), the obtained amount with small percentage
error is equals with real value
Figure 16: Changes in the pump head in terms of suction head
CONCLUSION
This research is a kind of validation of a hydraulic analysis tool in simulating flow in slurry pumps. In
addition to the pumps, it can simulate slurry flow in hydrocyclones and other similar equipment.Compatibility of
practical test values with simulation results indicates that hydraulic analysis software such as Ansys-Cfx is an
effective tool for simulating slurry pumps
The prediction of wear life of parts, the identification of the wearable points, the measurement of the
wear rate, the achievement of friction loss reduction solutions in the chamber, the effect of slurry characteristics
on the performance of the pump and other related topics are among the most important research subjects in
the field of slurry pumps that with help of Hydraulic analysis software can be studied
REFERENCES
American National Standards Institute, Inc., 2011. “American National Standard for Rotodynamic (Centrifugal) Slurry Pumps for
Nomenclature”, Definitions, Applications, and Operation (ANSI/HI 12.1- 12.6-2011), Hydraulic Institute, New Jersey.
K. C. WILSON; G. R. ADDIE; A. SELLGREN; “SLURRY TRANSPORT USING CENTRIFUGAL PUMPS”, 2006 Impeller Eyeer Science-I-
Business Media, Inc.
Satish Kumar; B. K. Gandhi; S. K. Mohapatra;” Performance Characteristics of Centrifugal Slurry Pump with Multi-Sized Particulate Bottom
and Fly Ash Mixtures”, Particulate Science And Technology · September 2014, 32:5, 466-476
Yao Wang, Ming J. Zuo; Xianfeng Fan; “Design of an Experimental System for Wear Assessment of Slurry Pumps”, Proceedings of the
Institution of Mechanical Engineers. Part A, Journal of power and energy, 2007, 211: 147-157
C.I. Walker; A. Roudnev; 2002. “Slurry pump impeller wear: comparison of some laboratory and field results”, Proceedings of the 15th
International Conference on Hydrotransport, BHR Fluid Engineering, Banff, Canada, 2002, 725-736
G.R.Addie and A. Sellgren, “The effect of wear on theperformance of centrifugal slurry pumps”, Proceedings
of ASME Fluids Engineering Division Summer Meeting, Washingdon, DC.
Warman International; 1991. “Slurry testing of centrifugal pumps”, Technical Bulletin, 1991, No. 12