CFD Analysis of Fluid Mechanics in Axial Flow Pumps: A Report

This report provides a detailed analysis of Computational Fluid Dynamics (CFD) applied to axial flow pumps, emphasizing the governing partial differential equations and their transformation into solvable algebraic equations. It highlights the use of CFD for quantitative and qualitative predictions of fluid flows through mathematical modeling, discretization, and software tools. The report discusses the importance of axial flow pumps in various systems, including municipal water supply and nuclear power plants, and addresses the complexities of turbulent flow within these pumps. It contrasts CFD with experimental methods, noting the advantages of speed, cost-effectiveness, and the ability to test multiple models, while also acknowledging limitations in model reliability and computational demands. The study reviews experimental studies, such as those by Mostafa Zierke and Boraey, and details the procedures for numerical simulations, including computational domain setup, mesh generation, and boundary conditions, ultimately summarizing the application of CFD in axial flow pump analysis and design. Desklib offers a range of study tools and solved assignments for students.

Fluid mechanics CFD analysis 1
FLUID MECHANICS CFD ANALYSIS
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Introduction
The flow of fluids in axial flow pumps is governed by the
partial differential equations which in most cases represents
the conservation laws for energy, momentum and mass. CFD
refers to the art of substituting such partial differential
equations technique with algebraic equations which can be
digitally solved using very fast computers (Ahir, 2015, p.
567).
CFD is a branch of fluid mechanics which uses numerical and
data structures analysis to solve and analyse problems which
involve the flow of fluids. Computers are always used to carry
out the computation which is needed to simulate the
correlation of liquids and gases which have surfaces that are

Fluid mechanics CFD analysis 3
clearly defined by their boundary conditions. By using high
speed supercomputers, it is possible to achieve better
simulations (Alexandrov, 2017, p. 43).
CFD offers a quantitative and qualitative prediction of fluid
flows by applying mathematical modelling, solution
techniques, discretization and software tools such as the pre-
processing utilities, post- processing utilities and solvers
Axial flow pumps are very common types of pumps which in
most cases comprises of the propeller in a pipe. The propeller
is driven by an electric motor or petrol/diesel engines which
are fixed to the tube from outside, sealed motor or a right-
angled drive shaft which cuts the pipe (Badr, 2015, p. 123).
The flow of the fluid particles through the pump don’t change
location because the suction change (entry radius) and the exit
(discharge) of the pump is small thus the term ‘axial’ pump.

Fluid mechanics CFD analysis 4
Most of the axial flow pumps have propellers-type of the
impeller which runs in the casing. The flow of fluids over the
blades of the impeller develops the pressure of the axial flow
pump. The fluid which flows through the pump is moved in
the direction which is parallel to the impeller shaft (fluid
particles) they do not change their radial location when
flowing through the pump. Due to that the fluid is allowed to
enter the propeller axially or axially discharge the fluid. The
axial flow pump propeller is driven by the motor. (Brandt,
2015, p. 289).
Importance of using CFD in different fields.
Application of the CFD has a lot of benefits which are
associated with it such as:
 In the automotive production Computational fluid dynamics
heaps the designers to enhance the aerodynamic
characteristics of the vehicles which they produce.

Fluid mechanics CFD analysis 5
 In architecture, computational fluid mechanics help the
architects to come up with designs which are safe and
comfortable environments to live in.
 For the industrial and chemical engineering it CFD helps
the chemical engineers maximize the output from their
equipment.
 Computation fluid dynamics assists the petroleum
engineers to come up with optimal oil recovery strategies.
 Computational fluid dynamics helps in the prevention of
natural disasters. The meteorologists can be able to use
CFD to warn of the natural disasters through weather
forecasting (Burrows, 2012, p. 675).
 For safety experts, it helps to reduce health risks from
different hazards such radiations.
 Computational fluid dynamics helps the military
personnel’s to estimate the damages which can be caused

Fluid mechanics CFD analysis 6
by different weapons and helps in the development of the
weapons.
 Accuracy: computational fluid dynamics is an approach
which uses the high-speed computers to solve partial
differential equations relating to the flow of fluids. In most
cases, it involves approximations to discretize the
mathematical equations. The applications of CFD in
solving problems which are associated with the flow of
fluids is very accurate since it involves the use of
computers.
 The use of computational fluids is very cost effective: the
only coats which are incurred when carrying out
computational fluids dynamics are only computing costs
and the cost for obtaining a license (Crouse, 2015, p. 76).
 The Computational fluid dynamics is very accessible in that
only that is required for you to carry out computational
fluid dynamics is a computer. The experiment on

Fluid mechanics CFD analysis 7
 The other hands are a very elaborate process. The first
thing which is needed to be done is to design your model
then involve the workshop to assist in fabrications then wait
for tunnel time slots.
Advantages of CFD over experimental work.
It is very fast and reliable in that one can be able to turn
around much faster as compared to experiments. One can be
able to test many models at a go since it involves the use of
computers.
The computational fluid dynamics is almost free since what
one is required to pay for is only the license for the software
as compared to the experiments which will require a lot of
resources to be able to be conducted (Dieguez, 2013, p. 173).
Coding is a very important element or tool which one needs to
know in general. The Computation fluid dynamics will enable
one to obtain the basic understanding of the fluids.

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Disadvantages of computational fluid dynamics over
experimental work.
For the computational fluid mechanics, not all the models
which are generated are reliable some of the models cannot be
generated which makes this technique to be very unreliable
unlike the experimental methods where the study of the
characteristics of the fluids can be easily carried out (Donald
M. Sandercock, 2016, p. 253).
When carrying out the simulation of very large simulations,
one can require very large and expensive computers which are
very hard to acquire.
Axial-flow pumps.
Axial-flow pumps comprise of a propeller which is confined
within a cylindrical casing which is often referred to as
propeller pump (Ganis, 2013, p. 76). Below is a well labelled

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schematic diagram of an axial –flow pump arranged for
vertical operations.
Numerical Simulation by use of Computational Fluid
Dynamic for the Axial-Flow Water Pump. To determine
Complex Turbulent flow.
The axial flow pumps are characterised by huge flow rates
and low discharge pressure. Due to those essential features,
the axial flow pumps are widely used in different systems
such as the municipal water supply, Municipal drainage

Fluid mechanics CFD analysis 10
system, water diversion systems, and irrigation systems and
for the major pump for nuclear power plants.
The flow of fluids in axial pumps is very unsteady, complex
and fully three-dimensional turbulent. The turbulent flow
which is complex as the one mentioned above dominates the
characteristics of efficiency, Performance, the vibration of the
pump and noise. Nevertheless, many of the physical
mechanisms and phenomena which are involved have
understood in details up to date, and is considered to be very
crucial in better understanding of the mechanisms and physics
behind the axial flow pump (García, 2018, p. 107).
The flow of fluids is very complex to be determined using the
ordinary experiments because of the pump rotor-stator, which
needs CFD numerical simulation methods. In the previous,
most of the experimental and numerical studies have been
conducted to understand the unsteady flow characteristics

Fluid mechanics CFD analysis 11
inside the axial-flow pumps (Grist, 2011, p. 45). From the
experiments which have been carried out the quantities which
were always the, parameters which mostly include the pump
efficiency and the rate of flow.The diagram below shows the
comparison between different impellers (Grondzik, 2015, p.
76).
Experimental studies on the axial flow pumps.
1. The experiment by Mostafa Zierke
The experimental study which was carefully designed on a
high-Reynolds-number through different measurements

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methods which include: calibrated five-hole pressure
investigates the determination of stagnation (Badr, 2015, p.
67)
2.0 Measurements of the axial and tangential velocities, by
Boraey
To measure tangible and axial velocities of the pump inlet
guide and the pump vane exit flow. Tip clearance and rotor
blade exist, an oil paint method for visualization of the skin-
friction and neighbouring end walls and the rotor blades
surface. Very successful feedback was obtained in this
experiment by using computational fluid dynamics numerical
(Urasak, 2016, p. 896). To understand the complex turbulent
flows and came up with ways through which it can be
enhanced.
Findings of the experimental studies.