DESIGN, ANALYSE AND MANUFACTURE PROPELLER BLADE FOR

REMOTELY UNDERWATER VEHICLE

ONG PUI SZE

Thesis submitted in partial fulfillment of the requirements

for the award of the degree of

Bachelor of Manufacturing Engineering

Faculty of Manufacturing Engineering

UNIVERSITI MALAYSIA PAHANG

JUNE 2013

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ABSTRAK

Projek ini mengandungi maklumat mengenai rekabentuk kipas untuk sebuah

Kenderaan Dalam Air Kawalan Jauh (ROV). ROV adalah satu teknologi yang sering

digunakan dalam ketenteraan, kejuruteraan laut dan aktiviti-aktiviti komersial seperti

industri-industri cari gali minyak. Sistem propulsi memainkan peranan yang penting

dalam keupayaan pergerakan ROV. Objektif tesis ini adalah untuk menjalankan

simulasi untuk rekabentuk dan pembentukan kipas dan membuatkan prototaip

dengan menggunakan mesin Fused Deposition Modelling. OpenProp merupakan satu

program yang dibentuk oleh Massachusetts Institute of Technology yang sesuai

digunakan untuk merekabentuk kipas dan dapat menganalisasikan prestasi

rekabentuk. Keputusan eksperimen menunjukkan prestasi dan daya tujahan sisihan

sebanyak 14% ke 19% apabila dibandingkan dengan keputusan teori. Ini disebabkan

oleh kesan dinding tangki air, kekasaran permukaan dan kesan pemotongan kipas.

Kesimpulannya, peningkatan harus dijalankan ke atas eksperimen untuk mendapat

keputusan yang lebih tepat.

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ABSTRACT

This thesis contains details on the designing a propeller for the Remotely Underwater

Vehicle. Remote Operated Vehicles (ROV) is a technology which is frequently used

to service the military, ocean engineering activities and also commercial activities

such as oil and gas industry. Propulsion plays a significant role in the

manoeuvrability of the ROV. The objective of this paper is to conduct simulation

studies to design and modelling the ROV propeller blade, and then manufacture the

prototype by using Fused Deposition Modeling machine. OpenProp, an open-sourced

program developed at Massachusetts Institute of Technology is used to design the

propeller and analyse the on-design performance of it. It is found that there is a

deviation of 14% to 19% on the experimental results compared to the theoretical

results. This might cause by wall effects that occurs on the tank, and surface

roughness and blunt trailing edge of the blade prototype. In conclusion, improvement

on the experimental setup is needed in order to obtain a much accurate results.

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TABLE OF CONTENTS

Page

SUPERVISOR’S DECLARATION ii

STUDENT’S DECLARATION iii

ACKNOWLEDGEMENTS iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF SYMBOLS xiii

LIST OF ABBREVIATIONS xv

LIST OF APPENDICES xvi

CHAPTER 1 INTRODUCTION

1.1 Background of Study 1

1.2 Problem Statement 4

1.3 Objectives 4

1.4 Scopes of Study 5

1.5 Limitation 5

CHAPTER 2 LITERATURE REVIEW

2.1 Propeller Physical 6

2.2 Propeller Mechanism 9

2.3 Motor 10

2.4 Type of Propellers 11

2.5 Propeller Material 12

2.6 Design Parameters 13

2.6.1 Blade Number 13

2.6.2 Propeller Diameter 14

2.6.3 Hub Diameter 16

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2.6.4 Chord to Diameter Ratio 17

2.6.5 Thrust 20

2.6.6 Drag 21

2.7 Design Considerations 25

2.7.1 Ventilation 25

2.7.2 Cavitation 26

2.8 Theory for Propeller Designing 26

2.8.1 Lifting Line Theory 26

2.8.2 Actuator Disk Theory 27

CHAPTER 3 METHODOLOGY

3.1 Flow Chart 29

3.2 Design Inputs 31

3.3 Analysis with OpenProp 31

3.3.1 Parametric Analysis 31

3.3.2 Single Propeller Design 32

3.4 Modelling of Propeller 34

3.5 Fabrication of Propeller 36

3.5.1 Rapid Prototyping 36

3.5.2 Other Manufacturing Process 37

3.6 Propeller Testing 38

CHAPTER 4 RESULTS

4.1 Simulation Results 40

4.1.1 Horizontal Propeller 40

4.1.2 Vertical Propeller 43

4.2 Stress Analysis 45

4.3 Test Rig 48

4.4 Propeller 50

4.5 Thrust and Efficiency Test 51

4.6 Discussions 51

4.6.1 Wall Effect 51

4.6.2 Blunt Trailing Edge 52

4.6.3 Surface Roughness 53

4.6.4 Limitation of Machine 53

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CHAPTER 5 CONCLUSIONS

5.1 Conclusions 54

5.2 Recommendations 55

REFERENCES 56

APPENDICES 60

x

LIST OF TABLES

Table No. Title Page

2.1 The chord over diameter at each blade section 20

4.1 Simulation results of 4-, 5-, and 6-blade propellers 41

4.2 Simulation results of 4-, 5-, and 6- bladed vertical propeller 44

4.3 Thrust force and efficiency 51

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LIST OF SYMBOLS

A Total hull area that sink in the fluid

d Hub diameter

D Drag

F Force

g Gravity

I Current

Length of the geometry

m Mass

P Power

Q Torque

r Radial

T Thrust

v Speed

Angular velocity

V Vehicle velocity

Voltage

W Weight

Z Number of blades

θ Angle

η Efficiency (in general)

ρ Density

ϕ Pitch angle

μ Kinematics viscosity

ω Propeller speed

Area (in general)

Cylindrical area of ROV

Rectangular area of ROV

Total area of ROV

Total area where propeller swept through

Drag coefficient

Drag coefficient of cylindrical

Drag coefficient of rectangular

Thrust coefficient

Propeller diameter

No load current

Torque coefficient

Revolution per minute per volt

Speed through the propeller

Efficiency of the motor

Efficiency of the propeller

Efficiency of the propeller mechanism

Efficiency of the gear box

Efficiency of the actuator disk

CP Propeller power coefficient

CQ Actuator disk torque coefficient

xiv

CT Actuator disk thrust coefficient

KT Propeller thrust coefficient

KQ Propeller torque coefficient

EFFY Efficiency

ADEFFY Actuator disk effiency

Js Advance coefficient

Pt Pitch

Re Reynolds number

xi

LIST OF FIGURES

Figure No. Title Page

1.1 The propulsion system of an AUV where P is the propeller, G 2

represents the gear, M for Motor, C for motor controller and B

as the batteries

1.2 ROV developed that need a set of customize propeller 3

2.1 Propeller nomenclature 6

2.2 A rearward rake with angle, θ 7

2.3 The cross section of the blade 7

2.4 The blade on the left is slightly bent due to low thickness 8

2.5 Basic propeller geometry 8

2.6 The pressure face and suction back 8

2.7 Pitch and pitch angle 9

2.8 The mechanism of thrusting of the propeller 10

2.9 The comparison of efficiency and shaft torque for both 3-bladed 13

and 6-bladed propellers under a range of advance coefficient

2.10 Variation of thruster power requirements versus the propeller 15

diameter for various force and thrust density

2.11 The comparison of the efficiency of the existing model of ROV 16

for a range of diameter, where solid line represents the thrust

coefficient and the dotted line is the actuator disk efficiency

which is 10 times of thrust coefficient

2.12 Effect of the variation of hub diameter towards the propeller 17

efficiency

2.13 Efficiency versus advance ratio for small, medium and large BAR 18

2.14 The efficiency of the propeller is 78.73% before the chord over 19

diameter are reduced

2.15 The efficiency of the propeller is 78.83% after the chord over 19

diameter are reduced

2.16 Percentage of drag force increase in vehicle for a range of 22

diameter under different tunnel drag coefficient

2.17 Drag coefficient for common geometry 23

2.18 Drag coefficient of cylindrical bodies at different aspect ratio 24

2.19 Mean drag coefficients of rectangular cylinders with different 24

aspect ratios

2.20 Hydrodynamic model of a propeller 27

3.1 Flow chart 30

3.2 Parametric analysis by OpenProp v2.4.6 32

3.3 The GUI for single propeller design 33

3.4 The results for single ducted propeller analysis 34

3.5 Propeller drawn in Solidworks 35

3.6 Fine gaps on trailing edge of the blades 36

3.7 Propeller parts before assemble 37

3.8 Test rig for propeller efficiency and drag 38

4.1 Single design of the 6-bladed propeller 40

4.2 Lift distribution of the 6-blade design with duct 42

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4.3 Cross sections of blade at different blade stations 42

4.4 3D view of the complete propeller model 43

4.5 Cross sections of blade at different blade stations 44

4.6 3D view of the complete propeller model 45

4.7 Von Mises Stress of Horizontal Propeller 46

4.8 Von Mises Stress of Vertical Propeller 46

4.9 Displacement of Horizontal Propeller 47

4.10 Displacement of Vertical Propeller 47

4.11 Test rig 48

4.12 Von Mises stress of test rig 49

4.13 Displacement of test rig due to the load 49

4.14 Horizontal propeller 50

4.15 Vertical propeller 50

A1 Top view of ROV 60

A2 Free body diagram of ROV during vertical movement 62

B1 Front view of ROV 64

B2 Free body diagram of the ROV during horizontal movement 65

C1 Free body diagram of test rig 66

D1 DC Power Supply 68

D2 Free body diagram of test rig with propeller moving 67

F1 Free body diagram of Test rig (center of gravity) 71

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LIST OF APPENDICES

Appendix Title Page

A Thrust Calculation for Vertical Propeller 60

B Thrust Calculation for Horizontal Propeller 64

C Experimental Thrust Calculations 66

D Propeller’s Experimental Efficiency Calculations 67

E Percentage Deviation Calculations 70

F Calculations of Additional Weight to Stabilize the Rig 71

xv

LIST OF ABBREVIATIONS

ABS Acrylonitrile Butadiene Styrene

BAR Blade area ratio

CFD Computational Fluid Dynamic

CNC Computational Numerical Control

DAR Developed Area Ratio

EAR Expanded Area Ratio

FEA Finite element analysis

FDM Fused Deposition Modelling

GUI Graphical user interface

MIT Massachusetts Institute of Technology

ROV Remotely underwater vehicle

RP Rapid Prototyping

RPM Revolution Per Minute

RPS Revolution Per Second

UUV Unmanned underwater vehicle

CHAPTER 1

INTRODUCTION

1.1 BACKGROUND OF STUDY

A number of underwater vehicles are developed, where it is divided into two

types which are manned underwater vehicle and unmanned underwater vehicle. The

manned underwater vehicle is usually used to service the military and also gather

data about the ocean. Today, there are two types of unmanned underwater vehicle

(UUV) which is the remote operated vehicle (ROV) and autonomous underwater

vehicle (AUV).

Though ROV and AUV is both categorized as UUV, Blidberg (2001)

however has proposed that the main difference between both is ROV is tethered in

order to obtain power supply and transmit signals such as position while AUV has

their own power and control itself to accomplish the task.

Hoang and Kreuzer (2007) recommended that ROV can be equipped with

different sensors. It is launched into the water from the mothership and was

controlled to reach to the structure that task is needed to be conducted. ROV is used

in the oil industry for almost three decades where it is useful in constructing

production facilities, inspection and intervention (Liu Hsu et al., 2000).

Azis et al. (2012) suggested that ROV can be utilize in inspection of cracks

on the underwater section of the ship, oil and gas industry, telecommunication,

geotechnical investigation and mineral exploration, which is mainly a hazardous

environment for human to work. Bessa et al. (2008) suggested that the development

of underwater vehicles enable tasks such as inspection and repair of offshore

2

structures, assembly and sub-sea phenomena to be completed without risking the

human life by positioning and controlling the altitude of the vehicle automatically.

Propeller is a device that consists of several blades that rotates to accelerate

the fluid along the propeller axis, which produce thrust force in the opposite direction

(Palmer, 2009). The performance of the blade can be affected by its rotational speed

and the flow into the propeller (Palmer, 2009). The propulsion system consists of

several components, which are the propeller, gear, motor, controller and batteries.

Figure 1.1: The propulsion system of an AUV where P is the propeller, G represents

the gear, M for Motor, C for motor controller and B as the batteries.

Source: Palmer (2009)

The performance of the propulsion system is the ratio of power output

(generated thrust and resultant speed of the vehicle) to the power input supplies by

the batteries (Palmer, 2009). Others include the vibrations produced by the propeller

to the hull, and noise generated by the system affect the performance of the

propulsion system.

This paper describes the process of propeller design of a ROV developed by

Professor Dr. Hj. Zahari Taha, which is shown in Figure 1.2. The goal is to design a

set of propeller (two vertical propellers and three thruster propellers) for the ROV.

The objective of this study is to design the ROVs’ propellers.

3

The design specifications are as follows:

Speed, v = 1.0m/s

Motor speed, ω = 85rpm (no load)

Motor speed, ω = 80rpm (at cruise)

Propeller hub diameter = 15% of the propeller diameter

Torque, Q = 9.3256 Nm

Power, P = 78.1256 W

The motor speed is set at 80rpm to ensure that the motor will be operating in

the safe range to prolong the motor’s life cycle.

Figure 1.2: ROV developed that need a set of customize propeller.

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1.2 PROBLEM STATEMENT

Recently, the development of ROV has stressed on smaller size and a more

efficient energy technology. Propeller of the ROV plays a significant role in

producing a more efficient horizontal and vertical movement. However, the number

of research on designing and manufacturing marine propeller is less.

Most of them rely on the propeller of the airplane for propulsion as off the

shelf propeller is more desirable because it is cheaper and easy to replace. It is much

more expensive to fabricate a customize propeller compare to buying one from the

shelf. Yet the use of airplane propeller in marine vehicle is not suitable because the

density of air is 1000 times less than water (D’Epagnier, 2006).

On the other hand, the development of new tools in propeller designing has

shown a significant improvement in the design method that could enhance the

process of propeller designing. However, the impact of development has yet not

shown due to the designers halt at the traditional method that has gone through loads

of researches and were validated, which is much more reliable and most importantly

were implemented for plenty of times (Kuiper, 2010).

Therefore, it is important for this research to clearly show the stages and steps

of the advance method in ROV propeller development which will encourage

engineers to adapt and pursue the new design and manufacturing method.

1.3 OBJECTIVES

The objectives of this thesis are:

i. To conduct simulation studies on ROVs propeller blade

ii. To design and modeling of a ROVs propeller blade

iii. To manufacture the propeller blade of ROV

iv. To test the ROVs propeller blade

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1.4 SCOPES OF STUDY

This research focuses on the hydrodynamic performance of the ROV where

an efficient propeller is needed to be designed and manufacture in order to produce a

reliable propulsion system.

The scopes of the study on ROVs propeller blade are:

i. To study the design process of ROVs propellers

ii. To design a propeller blade for ROVs by applying the existing method

iii. To do computational simulation on the design

iv. To manufacture the design by using the existing machines and equipment in

the faculty

v. To test the effectiveness of the design

1.5 LIMITATION

The limitation in this project is the manufacturability of the machines in the

Faculty of Manufacturing Engineering as these machines such as milling machine,

turning machine, electrical discharge machine, and others are not suitable for

machining propellers with irregular shape. The milling machine in the laboratory has

only 3-axis whereas it requires a 5-axis machining in order to machine the propeller

or turbines (Hurco Companies, Inc., 2012).

Most of the papers suggested to use 3-D printer to manufacture the propeller

as it is easier and more efficient than the other manufacturing method. Although the

cost of rapid prototyping is high, the propeller will be manufactured by using rapid

prototyping for better precision.

CHAPTER 2

LITERATURE REVIEW

2.1 PROPELLER PHYSICAL

The radius of the propeller is the distance from the tip of the blade to the

center of the hub (Duelley, 2010). The chord of the propeller is a straight line

distance from the leading edge to the trailing edge at a particular blade section of the

propeller (Duelley, 2010). Figure 2.1 shows the nomenclature of the propeller as

described.

Figure 2.1: Propeller nomenclature

Source: Duelley (2010) and Schultz (2009)

Rake is the angle of the propeller blade from the centerline of the hub. Figure

2.2 shows the rake angle of the propeller (Duelley, 2010).

Camber of the propeller is the maximum distance between the mean line and

the chord line. The maximum thickness of the blade is measured in a normal to the

chord line (Ferrando, 2012). The ideal propeller would be infinitely thin so that it is

more hydrodynamic (Duelley, 2010). However, this is impractical and impossible to

be achieved because it is not manufacturability, durability and efficient. Low

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thickness profile has the risk of breaking or bending when the blade is handled

roughly as shown in Figure 2.3 and Figure 2.4 below (Duelley, 2010).

Figure 2.2: A rearward rake with angle, θ.

Source: Duelley (2010)

Figure 2.3: The cross section of the blade.

Source: ITTC

Besides, the blade is classified into two, which is the leading edge and the

trailing edge which is illustrated on the Figure 2.5 above. Leading edge is the first

part that contact with water when it is rotating while trailing edge is the last part of

the blade that contact with the water. From Figure 2.6 below, it can clearly be seen

that the pressure face of the propeller where it has high pressure at that part. The

suction back has low pressure which is the cause of the ROV to move forward.

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Figure 2.4: The blade on the left is slightly bent due to low thickness.

Source: Duelley (2010)

Figure 2.5: Basic propeller geometry.

Source: US Navy

Figure 2.6: The pressure face and suction back

Source: US Navy

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Pitch is a measurement of the distance of propeller would move parallel to the

direction of motion when it rotates at one revolution (Duelley, 2010). High pitch over

diameter ratio can increase the propeller efficiency (D’Epagnier, 2006). Pitch angle

is the angle of the blade that is perpendicular to the water flow. It can be calculated

using the Equation (2.1), where Pt is the pitch of the propeller, ϕ is the angle and r is

the radial distance of any point on the blade from the center. Figure 2.7 explain

about the pitch of a propeller.

(2.1)

Figure 2.7: Pitch and pitch angle

Source: US Navy

2.2 PROPELLER MECHANISM

Propeller blade and aircraft wing has similarity in the way they work where

the difference is the type of fluid that flow through it. Water flow through the

propeller blade and causes pressure differences on the top and bottom of the blade

and therefore generate thrust force to the ROV. The velocity of the water is higher at

the suction back part of the blade and cause low pressure than the pressure face.

Figure 2.8 below shows that the resultant force of the ROV causes it to move

forward.

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Figure 2.8: The mechanism of thrusting of the propeller

Source: US Navy

2.3 MOTOR

The torque, Q of the motor is calculated by Equation (2.2) as shown in below

(Duelley, 2010).

( ) (2.2)

where is the torque constant (Nm per amp), I is the current drawn by the motor

(amp) is the no load current (amps) and is the revolution per minute per volt.

is calculated by the following Equation (2.3) (Duelley, 2010).

(2.3)

The electrical power, P of the motor is found to be 78.1256W by using

Equation (2.4) and Equation (2.5) show below (Duelley, 2010).

(2.4)

(2.5)

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The velocity of the vehicle can be calculated by substituting the power and

drag to Equation (2.6) below, where T is the drag and V is the vehicle velocity.

(2.6)

Stanway and Stefanov-Wagner proposed that the efficiency of the propeller

could be estimated by relating it with the efficiency of the motor ( ), gear box

( ), propeller mechanism ( ) and also the efficiency of the propeller ( ) which

is shown in Equation (2.7) (2006).

(2.7)

By using the approach introduced by Duelley, it was found that the torque

produced by the motor is 9.3256Nm and therefore power needed for one motor is

78.1256W.

2.4 TYPE OF PROPELLERS

There are eight types of propeller, which is fixed pitch propellers, ducted

propellers, podded and azimuthing propulsors, contra-rotating propellers,

overlapping propellers, tandem propellers, controllable pitch propellers, and

cycloidal propellers. Each propeller has its own characteristics that are suitable for

certain applications.

Stanway (2006) has used a ducted contra-rotating type of propellers on his

ROV. Contrarotating propellers provide higher efficiency and thrust compared with

single propeller because the load is supported by both propellers which therefore

enable them to have higher efficiency even in low rotational speeds. Besides,

counter-rotating effect of both propellers has the advantage of cancel out the losses

due to the tangential velocities in the wake (Stanway and Stefanov-Wagner, 2006).

However, contrarotating propeller produces some mechanical loss and a potential

failure point (Stanway and Stefanov-Wagner, 2006).