A Study on Velocity Profile in Pump Impeller and Casingeprints.utm.my/id/eprint/34595/1/NorMerlisaBintiAliMFKM2008.pdf · 2.1 (a) Spiral casing (front) of the laboratory centrifugal

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A STUDY ON VELOCITY PROFILE IN PUMP IMPELLER AND ITS CASING

NOR MERLISA BINTI ALI

A project report submitted in partial fulfillment of the

requirements for the award of the degree of

Master of Mechanical Engineering.

Faculty of Mechanical Engineering

Universiti Teknologi Malaysia

DISEMBER 2008

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To my beloved papa and mama

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ACKNOWLEDGEMENTS

Very special thanks to my project advisor, Dr. Jamaluddin Md. Sheriff for

sharing with me his profound insights and give me guidance, ideas and support in doing

this project.

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ABSTRACT

This project is to study velocity profile in pump impeller and its casing using numerical

simulations in commercial software COSMOSFloWorks. The pump has different

number of blades of impeller and a circular casing. The numerical simulations are

carried out with a multiple frame of reference to predict the velocity distribution around

the pump impeller and the casing. The impeller is solved in a rotating frame and the

casing is solved in a stationary frame. This study also shows that the number of blades

in impeller, flowrate and the impeller speed give a great influence in velocity

distribution in pump. The turbulence model used in this study is standard ε−k

Turbulence Model. The velocity distribution is observed by varying the impeller speed

and the flowrate for every number of blades in impeller.

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ABSTRAK

Projek ini adalah untuk mengkaji bentuk halaju di dalam penolak pam dan sarungnya

dengan menggunakan simulasi penomboran dalam perisian komersial

COSMOSFloWorks. Pam ini mempunyai nombor bilah yang berlainan pada

penolaknya dan satu sarung yang berpusing bentuknya. Simulasi penomboran yang

dijalankan menggunakan rujukan bingkai yang pelbagai untuk mengjangka taburan

halaju di sekeliling penolak pam sarungnya. Penolak pam diselesaikan di dalam bingkai

yang berputar manakala sarung pam diselesaikan menggunakan bingkai yang pegun.

Kajian ini juga menunjukkan bahawa bilangan bilah pada penolak pam, kadar aliran dan

kelajuan penolak pam memberi pengaruh yang besar dalam taburan halaju di dalam

pam. Model Golakan (Turbulence Model) yang digunakan di dalam kajian ini ialah

‘standard ε−k Turbulence Model’. Taburan halaju dikaji dengan mengubah halaju

penolak pam and kadar aliran bagi setiap penolak pam yang mempunyai bilah yang

berbeza- beza.

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TABLE OF CONTENTS

CHAPTER TITLE PAGE

Declaration ii

Dedication iii

Acknowledgements iv

Abstract v

Abstrak vi

Table of Contents vii

List of Tables ix

List of Figures x

List of Symbols xii

List of Appendices xiii

I INTRODUCTION

1.1 Background of Project 1

1.2 Problem statement 2

1.3 Objective of Project 2

1.4 Scope of Project 3

1.5 Methodology 3

1.6 Significance of Project 4

1.7 Thesis Outline 4

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II LITERATURE REVIEW

2.1 Introduction 6

2.2 Centrifugal Pump 7

2.2.1 Stationary Components 7

2.2.2 Impeller 8

2.2.2.1 Type of Impeller 9

2.2.3 Working Principle of Centrifugal Pump 10

2.3 Basics Pump Law 10

2.4 Numerical Method 11

2.5 Basic Equation and Turbulence Model Description 14

2.5.1 Basic Equation 14

2.5.2 Turbulence Model 16

2.5.3 The standard ε−k Turbulence Model 17

2.6 Velocity Profile Around Impeller 18

III RESEARCH METHODOLOGY

3.1 Introduction 20

3.2 Research Route 20

3.3 Collecting Information from Literature Review 22

and Reference Books

3.4 Numerical Method 22

3.5 Steps in Numerical Simulations 24

3.6 Flow Solver 25

3.7 Assumptions of the Study 25

3.8 Initial Conditions 25

3.9 Boundary conditions 26

3.9.1 Inlet Conditions 26

3.9.2 Outlet Conditions 27

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3.9.3 Wall Conditions 27

3.10 Analysis Type 27

3.11 Working Fluid Properties 27

IV RESULT AND ANALYSIS

4.1 Numerical Results 29

V CONCLUSION

5.1 Introduction 56

5.2 Recommendations 57

REFERENCES 59

APPENDICES A - C 65

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LIST OF TABLES

TABLE NO. TITLE PAGE

3.1 Properties of water with temperature 28

4.1 Maximum Velocity for Impeller Speed and Flowrate Varies 31

4.2 Velocity contour for impeller speed1500rpm ( 133.0 −= smQ ) 34

4.3 Velocity contour for impeller speed 1500rpm ( 135.0 −= smQ ) 35



4.6 Velocity contour for impeller Speed 2000 rpm )5.0( 13 −= smQ 39

4.7 Velocity contour for impeller speed 2000 rpm )0.1( 13 −= smQ 41

4.8 Velocity contour for impeller speed 2500 rpm ( )133.0 −= smQ 45

4.9 Velocity contour for impeller speed 2500 rpm ( )135.0 −= smQ 48

4.10 Velocity contour for impeller speed 2500 rpm )0.1( 13 −= smQ 51

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 (a) Spiral casing (front) of the laboratory centrifugal pump 8

2.1 (b) Spiral casing (back) of the laboratory centrifugal pump 8

2.2 Impeller of the laboratory centrifugal pump 9

2.3 CFD approaches used in turbo machinery

[Reza Aghaei tog et al, 2007] 13

2.4 Static pressure contours (Pa) at nominal flow rate

[Jose Gonzalez et al, 2002] 19

3.1 Research Route 21

3.2 The pump impeller with three blades 23

3.3 The circular casing with the inlet pipe. 23

3.4 The centrifugal pump with a rotating impeller 24

4.1 (a) Maximum velocity versus number of blades (2500rpm) 32

4.1 (b) Maximum velocity versus number of blades (2000rpm) 32

4.1 (c) Maximum velocity versus number of blades (1500rpm) 33

4.2 The velocity contour of front view of the pump

[Speed 2000rpm, flowrate = 0.5 13 −sm ] 40

4.3 The front view of the blade.


4.4 Velocity Vector in the pump.

[Front view, speed 2000rpm, flowrate = 0.5 13 −sm ] 41

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4.5 Velocity vector at the inlet pipe of the pump.

[Right view, speed 2000rpm, flowrate = 0.5 13 −sm ] 42

4.6 Velocity contour in the inlet pipe of the pump.

[Top view, speed 2000rpm, flowrate = 0.5 13 −sm ] 42

4.6 (a) Velocity vector in pump impeller of 3 blades.

[Front view, speed 2000 rpm, flowrate = 1.0 13 −sm ] 45

4.7 The velocity contour at the surface of the blade.


4.8 The velocity contour of the 3 blades impeller.


4.9 Velocity contour of the 4 blades impeller.


4.10 Velocity contour of the tip of blade for 4 blades impeller.


4.11 Velocity vector of the pump for 5 blades impeller.


4.12 Velocity contour of the pump for 5 blades impeller.












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LIST OF SYMBOLS

Q - Flowrate

n - Speed

H - Discharge head

P - Pressure

ρ - Density

V - Volume

T - Temperature

t - Time

τ - Shear stress

k - Turbulent kinetic energy

ε - Turbulent dissipation

eµ - Effective viscosity

l - Turbulent length scale

tυ - Turbulent viscosity

tkCCC σσ ,,,, 211 - Constants

K - Bulk Modulus of elasticity

υ - Kinematic viscosity

µ - Dynamic viscosity

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LIST OF APPENDICES

APPENDIX TITLE PAGE

A1 Velocity contour for impeller speed1500rpm ( 133.0 −= smQ ) 66

A2 Velocity contour for impeller speed 1500rpm ( 135.0 −= smQ ) 67



A5 Velocity contour for impeller Speed 2000 rpm )5.0( 13 −= smQ 70

A6 Velocity contour for impeller speed 2000 rpm )0.1( 13 −= smQ 71

A7 Velocity contour for impeller speed 2500 rpm ( )133.0 −= smQ 72

A8 Velocity contour for impeller speed 2500 rpm ( )135.0 −= smQ 73

A9 Velocity contour for impeller speed 2500 rpm )0.1( 13 −= smQ 74

B1 Pressure contour for impeller speed1500rpm ( 133.0 −= smQ ) 75

B2 Pressure contour for impeller speed 1500rpm ( 135.0 −= smQ ) 76



B5 Pressure contour for impeller Speed 2000 rpm )5.0( 13 −= smQ 79

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B6 Pressure contour for impeller speed 2000 rpm )0.1( 13 −= smQ 80

B7 Pressure contour for impeller speed 2500 rpm ( )133.0 −= smQ 81

B8 Pressure contour for impeller speed 2500 rpm ( )135.0 −= smQ 82

B9 Velocity contour for impeller speed 2500 rpm )0.1( 13 −= smQ 83

C Maximum Pressure for Impeller Speed and Flowrate Varies 84

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CHAPTER I

INTRODUCTION

1.1 Background of Project

This project is to study the velocity profile in pump impeller and its casing using

numerical methods. The method is using Computer Fluid Dynamics (CFD) by

numerical simulations in Solidworks (COSMOSFloWorks). A selected built-in model

of centrifugal pump is used in the numerical simulations. Centrifugal pump is basically

used to convert mechanical energy into hydraulic energy by centrifugal force on the

liquid used as a device to increase the pressure. Many researches have been done to

optimize the design of centrifugal pump by studying on its velocity profile either at the

pump impeller or in the casing. Some of the researches are based on a purpose to

eliminate the noise from the pump while it is working which produced from the passing

blade. But in this study, it is purposely to determine the velocity profile at the pump

impeller and its casing. Besides that, it is also to gain knowledge about the flow

distribution around the impeller and the casing of centrifugal pump by using the well-

known numerical method, CFD. By running several steps of simulations in the

commercial code COSMOSFloWorks, the flow distribution around the impeller and the

casing can be visualized. Some important parameters such as velocity, pressure and the

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turbulent energy are discussed further in the next chapter. The turbulent model which is

used in this study is the standard ε−K (two equations) turbulence model. The

numerical simulations by using the commercial code COSMOSFloWorks are used in

this study because it provides a faster way of simulation in order to study the flow

analysis especially in rotating components such as centrifugal pump.

1.2 Problem Statement

This study looks ahead to determine the velocity profile at the impeller and its

casing of selected centrifugal pump using numerical simulation. The centrifugal pump

will use variable speed and flow rate and water as its working fluid. The results

obtained will be analyzed to see the difference of velocity profile after applying variable

speed and flow rate to the pump model which has different number of blades.

1.3 Objectives of the Project

The objectives of this project include:

i. To study the velocity profile at the pump impeller and the casing by using

Computational Fluid Dynamics (CFD).

ii. To study the circulating flow around the impeller and the casing.

iii. To observe the velocity distribution at the impeller and the casing for

different impeller speed and flowrate.

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1.4 Scope of Project

The major focus of this project is:

i. Literature review on numerical approach using CFD especially on determination

of the velocity profile in rotating impeller and the casing of centrifugal pump.

ii. This project will be using the selected centrifugal pump model with variable

motor speed and flowrate.

iii. Water will be used its working fluid in the centrifugal pump.

1.5 Methodology

i. Collecting information from journals and books about the related researches

of determination of velocity profile in pump impeller and the casing of

centrifugal pump.

ii. Run the numerical simulation in Solidworks (COSMOS FloWorks) using the

model in the software.

iii. Analyzing the results of the numerical simulations.

iv. Developing conclusions, recommendations and implications of this study.

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1.6 Significance of Project

i. Encouragement for lots more studies and researches on the determination of

flow behavior in pump impeller and the casing by using other CFD software

and flow visualization methods such as PIV.

ii. An idea to other student or new researcher to do research project on flow

behavior (velocity profile) or other parameter such as pressure in pump

impeller and other component in centrifugal pump.

iii. An idea of determination of other flow parameters using other turbulence

model like RNG- ε−K turbulence.

1.7 Thesis Outline

The thesis is organized into five chapters. Chapter I contains of introduction,

objectives, methodologies used, scope and the significance of this study. The idea of

this study is explained in the introduction. Besides that, the problem statement of this

case study is also stated as the reason this project is launched. Chapter II explains about

the three keywords in this study: the centrifugal pump, velocity profile, and CFD. All

the governing equations, the Navier-Stokes equation are also explained in this chapter.

The related researches in other journals and books are reviewed in this second chapter.

Chapter III explains about the methodology of this study which has been used to

complete the project. The procedures of numerical simulation which is carried out by

using the commercial software COSMOSFloWorks are also discussed in this chapter.

The methods are discussed deeper including the initial and boundary conditions used in

this numerical simulation. Chapter IV discusses about the results of the numerical

simulation and the analysis of the result. Some figures of the velocity vectors and the

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velocity contours around the impeller are showed and explained. The last chapter

concludes the study, including with the recommendations for the future use and research

that might be used for others.

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Documents

A Study on Velocity Profile in Pump Impeller and Casingeprints.utm.my/id/eprint/34595/1/NorMerlisaBintiAliMFKM2008.pdf · 2.1 (a) Spiral casing (front) of the laboratory centrifugal