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DEVELOPMENT OF A FLOATING TYPE WATER

WHEEL FOR PICO HYDRO SYSTEMS

FINAL REPORT

Submitted to the DEPARTMENT OF MECHANICAL AND MANUFACTURING ENGINEERING

OF THE FACULTY OF ENGINEERING

In partial fulfillment of the requirements for the

Degree of Bachelor of Science of Engineering

By DIKKUMBURAGE N.S. . …………………………

(RU/E/2005/20)

PEIRIS A.P.T.S. …………………………..

(RU/E/2005/59)

PRABHASHANA H.P.D. …………………………..

(RU/E/2005/61)

Approved:

Dr. N. Hettiarachchi, Major Advisor (Academic)

Mr. Rohitha Ananda, Co Advisor (Practical Action) Mr. Gihan Sanjeew, Co Advisor (Practical Action)

DEPARTMENT OF MECHANICAL AND MANUFACTURING

FACULTY OF ENGINEERING UNIVERSITY OF RUHUNA

HAPUGALA GALLE

SRI LANKA

JUNE 2009

i

ACKNOWLEDGEMENT

Development of floating type water wheel for a Pico hydro system was a challenging but

interesting task. Throughout this brilliant social service we gathered vast knowledge and

experiences with the guidance and assistance from everyone who involved with this project.

We would like to take this opportunity to express our deepest gratitude to the following

people who helped us to complete this project with success.

First of all, we would like to thank Dr AMN. Alagiyawanna. the Dean of the Faculty of

Engineering and University of Ruhuna for giving us the opportunity to do this project.

Next our sincere thanks go to the Project coordinator. Dr. Nandita Hettiarachchi, for giving

us permission to carry out this project and also for his kind guidance throughout the whole

project.

Our heart-felt gratitude is offered to our co-advisers. Mr Rohitha Anada and Mr.Gihan

Sanjeew from Practical Action for their guidance and assistance which were always help for

us. Also they facilitated completely to this project in financially.

Dr. Sumith Baduge Head of the Department of Mechanical & Manufacturing Engineering is

reminded with appreciation for his guidance developing the theory for fluid dynamic

analysis.

We would like to thank all the staff of all the laboratories of the Department of Mechanical &

Manufacturing Engineering for their assistance in fabricating and developing our product

and preparation of our final reports.

ii

ABSTRACT

Pico hydro power generation by flowing water is the most economical trend to supply

electricity for rural areas. The impotency of floating type water wheel the zero head concept

.There is no effect to the generating power from the changing of water level. Even in dry zone

this product is applicable.

As Mechanical Engineering Undergraduates we were aiming to improve the overall working

efficiency while developing a new system or modification of the present system and transfer

the technology to the community. In this project report we discuss about the theoretical

background, designing steps, manufacturing, testing, and developing of floating type water

wheel. Practical experiences obtaining while carrying out this project also mentioned in this

report. This will be a understandable and valuable source for maximize the expectations of

the rural communality who suffer severe energy lacking.

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TABLE OF CONTENT

ACKNOWLEDGEMENT.............................................................................................................i

ABSTRACT.................................................................................................................................ii

TABLE OF CONTENT..............................................................................................................iii

LIST OF FIGURES..................................................................................................................vii

LIST OF TABLES......................................................................................................................ix

LIST OF GRAPHS....................................................................................................................xii

1. INTRODUCTION............................................................................................................. 1

1.1 WHY ARE THE PICO HYDRO SYSTEMS IMPORTANT........................................ 1

1.2 OVERVIEW OF WATER WHEEL .......................................................................... 1

1.3 OBJECTIVES OF THE STUDY ................................................................................. 4

1.4 SCOPE OF THE STUDY ............................................................................................ 4

2. LITERTURE REVIEW ..................................................................................................... 5

2.1 HISTORY OF WATER WHEELS .............................................................................. 5

2.2 TECHNOLOGY RELATED TO FLOATING TYPE WATER WHEEL ..................... 7

2.3 MODERN FEATURES OF FLOATING TYPE WATER WHEEL ............................. 7

2.4 PROBLEMS ENCOUNTERING AND OVERCOME ................................................. 9

3. THEORETICAL BACKGROUND OF THE WATER WHEEL ...................................... 11

3.1 NOMENCLATURE .................................................................................................. 11

3.2 THEORETICAL APPROACH .................................................................................. 12

3.3 DIMENSIONS OF THE MODEL ............................................................................. 14

3.4 ASSUMPTIONS ON THEORETICAL ANALYSIS ................................................. 15

3.5 THEORETICAL CALCULATION ........................................................................... 15

3.5.1 AVERAGE VELOCITY OF WATER FLOW .................................................... 17

3.5.2 CALCULATION OF FORCES .......................................................................... 18

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3.6 THEORETICAL RESULTS ...................................................................................... 21

3.7 DESIGN OF BREAKING LOAD TEST APPARATUS ............................................ 21

3.7.1 POWER TRANSMISSION BY A V- BELT ....................................................... 22

4. PREFOMENCE TESTING OF WATER WHEEL – 1st SERIES OF TESTING .............. 24

4.1 PERFORMANCE TESTING OF SIX BLADE STRAIGHT TYPE WATER WHEEL

........................................................................................................................................ 26

4.2 PERFORMANCE TESTING OF TWELVE BLADE STRAIGHT TYPE WATER

WHEEL .................................................................................................................... 29

4.3 PERFORMANCE TESTING OF SIX BLADE INCLINED TYPE WATER WHEEL 32

4.4 PERFORMANCE TESTING OF TWELVE BLADE INCLINED TYPE WATER

WHEEL .................................................................................................................... 35

4.5 PERFORMANCE TESTING OF TWELVE BLADE CURVED TYPE WATER

WHEEL .................................................................................................................... 38

4.6 COMMENTS ............................................................................................................ 41

4.7 DISCUSSION ........................................................................................................... 42

5. THEORETICAL DESIGN OF FLOATING TYPE WATER WHEEL ............................ 45

5.1 DESIGN PROCEDURE ............................................................................................ 45

5.1.1 DIMENSIONING OF WATER WHEELS MODELS ......................................... 45

5.2 THEORETICAL CALCULATIONS FOR WATER WHEEL MODELS ................... 46

5.2.1 AVERAGE VELOCITY OF WATER FLOW .................................................... 49

5.2.2 CALCULATION OF FORCES .......................................................................... 49

5.3 CONCLUSION ON THEORETICAL ANALYSIS ................................................... 54

6. MECHANICAL DESIGN OF FLOATING TYPE WATER WHEEL ............................. 55

6.1 DESIGN CALCULATIONS FOR SHAFT ................................................................ 55

6.1.1 VERTICAL FORCES CALCULATION ............................................................ 56

6.1.2 HORIZONTAL FORCE CALCULATION ......................................................... 57

6.2 BEARING CALCULATIONS FOR SHAFTS ........................................................... 62

6.3 DESIGN OF BLADE HOLDING RIM ..................................................................... 63

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6.4 DESIGN OF BLADES .............................................................................................. 63

6.5 DESIGN OF FLOTING STRUCTURE ..................................................................... 64

6.5.1 CALCULATIONS FOR FLOATING STRUCTURE .......................................... 64

7. MANUFACTURING TECHNIQUES FOR FLOATING STRUCTURE AND WATER

WHEEL .......................................................................................................................... 66

7.1 MANUFACTURING OF BLADES .......................................................................... 66

7.2 MANUFACTURING OF BLADE HOLDING WHEELS ......................................... 67

7.3 MANUFACTURING OF BEARING HOLDER ........................................................ 67

7.4 MANUFACTURING OF FLOATING STRUCTURE ............................................... 68

8. PERFORMANCE TESTING OF NEWLY DESIGNED MODELS ................................ 69

8.1 PERFORMANCE TESTING OF MODEL 1 ............................................................. 69





8.6 DISCUSSION ON RESULTS ................................................................................... 94

8.6.1 THE COMPARISON BETWEEN THEORETICAL AND PRACTICAL VALUES

OF OUTPUT POWER FOR EACH MODEL ...................................................... 94

8.6.2 EFFECT ON CHANGE IN PARAMETERS OF WATER WHEEL ................... 95

9. DEVELOPMENT OF END PRODUCT.......................................................................... 97

9.1 DEVELOPMENT OF WATER WHEEL................................................................... 97

9.2 DEVELOPMENT OF STRUCTURE ........................................................................ 97

9.3 DEVELOPMENT OF POWER TRANSMISSION METHOD .................................. 98

10. IMPLEMENT OF NEWLY DESIGNED FLOATING TYPE WATER WHEEL........... 99

10.1 ELECTRICAL PART OF THE WATER WHEEL .................................................. 99

10.2 EFFECTIVENESS OF THE FLOATING TYPE WATER WHEEL ...................... 101

11. CONCLUSION AND RECOMMENDATION ............................................................ 103

vi

12. REFERENCES............................................................................................................ 106

APPENDICES .................................................................................................................. 107

A 1 ................................................................................................................................ 107

A 2 ................................................................................................................................ 109

vii

LIST OF FIGURES

Figure 2.1: Ancient Water Wheel .......................................................................................... 5

Figure 2.2: Undershot water wheel ........................................................................................ 7

Figure 2.3: Mangal waterwheel ............................................................................................. 9

Figure 3.1 Forces On Water Wheel Blade ........................................................................... 12

Figure.3.2 Tested Model of Water Wheel ............................................................................ 15

Figure 3.3: Forces on Belt Drive ......................................................................................... 22

Figure 4.1: Testing Apparatus ............................................................................................. 24

Figure 4.2: Straight Type Blade ........................................................................................... 25

Figure 4.3: Inclined Blade at Angle 20° ............................................................................... 25

Figure 4.4: Curve Type Blades ............................................................................................ 25

Figure 6.1: Layout diagram of Input shaft ........................................................................... 56

Figure 6.2: Vertical Load diagram of shaft .......................................................................... 57

Figure 6.3: Horizontal Load diagram of shaft ...................................................................... 58

Figure 6.4: bending moment diagram of shaft..................................................................... 58

Figure 6.5: Vertical bending moment diagram of shaft ........................................................ 60

Figure 6.6: Horizontal bending moment diagram of shaft .................................................... 60

Figure 6.7: Resultant bending moment diagram of shaft ...................................................... 61

Figure 6.8: Designed model of floating type water wheel .................................................... 65

Figure 7.1: Different types of Blades ................................................................................... 66

Figure 7.2: Blade Holding Wheels ....................................................................................... 67

Figure 7.3: Bearing Holder .................................................................................................. 67

Figure 7.4: Floating Structure .............................................................................................. 68

Figure 7.5: Assembled floating type water wheel ................................................................ 68

Figure 9.1: Edge covered curve blade .................................................................................. 97

Figure 9.2: Supporting structure .... ............................................................................................. 97

Figure 9.3: water flow guiding method ................................................................................ 97

viii

Figure 9.4: Power transmission apparatus ............................................................................ 98

Figure 10.1: Setting at water................................................................................................ 100

Figure 10.2: Electrical testing.. .......................................................................................... 100

Figure A 2.1: Cross section of V-Belt ................................................................................ 109

Figure A 2.2: Cross section of V-grooved pulley ............................................................... 110

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LIST OF TABLES

Table No.1.1: Types of Water wheels .................................................................................... 2

Table No. 3.1: Nomenclature............................................................................................... 11

Table No. 3.2: α and m Values ........................................................................................... 16

Table No. 3.3: m and S Values ............................................................................................ 17

Table No. 3.4: Values For m, Vam, Vt, Vr, γ and ε Parameters ............................................. 18

Table No. 3.5: Values For P, R, F, Fu, M and Nu Parameters .............................................. 19

Table No. 3.6: m and ω Values ............................................................................................ 20

Table No. 3.7: Theoretical Results for 6 Blade Straight Type Water Wheel ......................... 21

Table No.4.1: Observation Values for Six Blade Straight Type Water Wheel ...................... 26

Table No.4.2: RPM Vs Power for Six Blade Straight Type Water Wheel ............................ 27

Table No.4.3: Observation Values for Twelve Blade Straight Type Water Wheel................ 29

Table No.4.4: RPM Vs Power for Twelve Blade Straight Type Water Wheel ...................... 30

Table No.4.5: Observation Values for Six Blade Inclined Type Water Wheel...................... 32

Table No.4.6: RPM Vs Power for Six Blade Inclined Type Water Wheel ............................ 33

Table No.4.7: Observation Values For Twelve Blade Inclined Type Water Wheel .............. 35

Table No.4.8: RPM Vs Power For Twelve Blade Inclined Type Water Wheel ..................... 36

Table No.4.9: Observation Values for Twelve Blade Curved Type Water Wheel ................ 38

Table No.4.10: RPM Vs Power for Twelve Blade Curved Type Water Wheel ..................... 39

Table No.4.11: Theoretical and Testing Results of Average Power and R.P.M of Water

Wheel ......................................................................................................... 42

Table No.4.12: Compare Of Testing Results for Water Wheels ........................................... 43

Table No. 5.1: α and m Values for M-1 .............................................................................. 48

Table No. 5.2: m and S Values for M-1 ............................................................................... 48

Table No. 5.3: Values For m, Vam, Vt, Vr, γ and ε Parameters for M-1 ................................ 49

Table No. 5.4: Values For P, R, F, Fu, M and Nu Parameters for M-1 ................................. 51

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Table No. 5.5: m and ω Values for M-1 ............................................................................... 52

Table No. 5.6: Specification Summery of Models ............................................................... 53

Table No. 5.7: Output Summery of Models ......................................................................... 53

Table No. 5.8: Output Summery of Models ......................................................................... 54

Table No.8.1: Observation Values for Model 1 ................................................................... 69

Table No.8.2: RPM Vs Power for Model 1 .......................................................................... 70

Table No.8.3: RPM Vs Efficiency for Model 1 .................................................................... 72







Table No.8.10: Observation Values for Model 4.................................................................. 84

Table No.8.11: RPM Vs Power for Model 4 ........................................................................ 85

Table No.8.12: RPM Vs Efficiency for Model 4 .................................................................. 87

Table No.8.13: Observation Values for Model 5.................................................................. 89

Table No.8.14: RPM Vs Power for Model 5 ........................................................................ 90

Table No.8.15: RPM Vs Efficiency for Model 5 .................................................................. 92

Table No.8.16: Theoretical and practical values of output power for each model ................. 94

Table No.8.17: Experimental Values for M -4 and M-5 (Width) .......................................... 95

Table No.8.18: Experimental Values for M -1 and M-3 (Curve) .......................................... 95

Table No.8.19: Experimental Values for M -2 and M-5 (Diameter) ..................................... 96

Table No.8.20: Experimental Values for M -1 and M-4 (Depth) .......................................... 96

Table No.10.1: The connected power generator specifications ............................................. 99

Table No.11.1: Comparison between Pico Hydro Vs Other energy sources (May-2009) .... 103

xi

Table No.11.2: Implement floating type water wheel model .............................................. 104

Table No.11.3: Cost analysis for floating type water wheel for Pico Hydro units (RUFW-12-

20x40) (May-2009)....................................................................................... 104

Table No. A 1.1: Flat Plate, Drag And Lift Coefficients. ................................................... 107

Table No: A 2.1: Dimensions of standard V-belts according to IS: 2494-1974................... 109

Table No: A 2.2: Dimensions of standard V- grooved pulleys according to IS: 2494-1974 110

xii

LIST OF GRAPHS

Graph No.4.1: Power Vs RPM for 6 blade straight type water wheel .................................. 28

Graph No. 4.2: Power Vs RPM for 12 blade straight type water wheel ................................ 31

Graph No. 4.3: Power Vs RPM for 6 blade inclined type water wheel ................................ 34

Graph No. 4.4: Power Vs RPM for 12 blade inclined type water wheel ............................... 37

Graph No. 4.5: Power Vs RPM for 12 blade curved type water wheel ................................ 40

Graph No. 8.1: Power Vs RPM for the model 01(M-1) ....................................................... 71

Graph No. 8.2: Efficincy Vs RPM for the model 01(M-1) ................................................... 73

Graph No. 8.3: Power Vs RPM for the model 02(M-2) ........................................................ 76

Graph No.8.4: Efficincy Vs RPM for the model 02(M-2) .................................................... 78

Graph No.8.5: Power Vs RPM for the model 03(M-3) ......................................................... 81

Graph No.8.6: Efficincy Vs RPM for the model 03(M-3) .................................................... 83


Graph No.8.8: Efficincy Vs RPM for the model 04(M-4) ................................................... 88


Graph No.8.10: Efficincy Vs RPM for the model 05(M-5) .................................................. 93

Graph No.A1.1: Drag and Lift Coefficients for Different α..................................................108

Project Report Development of Floating Type Water Wheel For Pico Hydro System

Department of Mechanical & Manufacturing Engineering 1

1. INTRODUCTION

In hydro power systems, energy of water is using for power machinery or generate electricity.

Hydropower is a renewable energy resource. The energy of this water cycle, which is driven

by the sun, can be tapped to produce electricity or for mechanical tasks.

When flowing water is captured and turned into electricity, it is called hydroelectric power or

hydropower. There are several types of hydroelectric facilities; they are all powered by the

kinetic energy of flowing water as it moves downstream. Turbines and generators convert the

energy into electricity, which is then fed into the electrical grid to be used in homes,

businesses, and by industry. Considering Sri Lankan situation hydro power takes place 8% of

total Energy generation and basically they obtain from large hydropower schemes. (Source:

Energy Conservation Fund- 2003)

1.1 WHY ARE THE PICO HYDRO SYSTEMS IMPORTANT?

Pico hydro power system is used to obtain electrical power which is lower than one kilowatt.

Compared with other Hydro power systems it is simple in construction, simple in

maintenance, can generate power 24 hours and low cost. Pico hydro systems are most

sustainable for rural villages of Sri Lanka. Because most of the hydro power sources are

located in rural villages.

This project had ultimately target to developing of floating type water wheel for hydro

system. Its special feature is that there is no head to give kinetic energy to the turbine.

1.2 OVERVIEW OF WATER WHEEL

A water wheel is a machine for converting the energy of flowing or falling water into more

useful forms of power, in the past water wheels were used to mill flour in mills, also it was

used in foundry work and machining. A water wheel consists of a large wooden or metal

wheel, with a number of blades or buckets arranged on the outside rim forming the driving

surface. Most commonly, the wheel is mounted vertically on a horizontal axle, but some of

wheel is mounted horizontally on a vertical shaft.

There are several types of water wheels are existed in water wheel applications. The major

types of water wheels are discussed briefly in Table No.1.1



Table No.1.1: Types of Water wheels

Water Wheel Description

Horizontal wheel (Norse mill) The wheel is mounted inside the (mill)

building below the working floor.

A jet of water is directed on to the paddles of

the water wheel, causing them to turn.

This is a simple system, usually used simply

spindle.

Undershot wheel

A vertically-mounted water wheel that is

rotated by water striking paddles or blades at

the bottom of the wheel is

This is generally the least efficient, oldest type

of wheel

cheaper and simpler to build,

Less powerful and can only be used where the

flow rate is sufficient to provide torque.

Undershot wheels gain no advantage from

head. They are most suited to shallow

streams in flat country.

Undershot wheels are also well suited to

installation on floating platforms.

Overshot wheel

A vertically-mounted water wheel that is

rotated by falling water striking paddles,

blades or buckets near the top of the wheel.

A typical overshot wheel has the water

channeled to the wheel at the top and slightly

to one side in the direction of rotation. The

water collects in the buckets on that side of

the wheel, making it heavier than the other

"empty" side. The weight turns the wheel,



can use all of the water flow for power (unless

there is a leak)

does not require rapid flow.

gain a double advantage from gravity.

Overshot wheels demand exact engineering

and significant head, which usually means

significant investment in constructing a dam,

millpond and waterways.

Backshot wheel

A variety of overshot wheel where the water

is introduced just behind the summit of the

wheel.

To function until the water in the wheel pit

rises well above the height of the axle, when

any other overshot wheel will be stopped or

even destroyed.

Suitable for streams that experience extreme

seasonal variations in flow, and reduce the

need for complex sluice and tail race

configurations.

Gain power from the water's current past the

bottom of the wheel, and not just the weight

of the water falling in the wheel's buckets.

In this project ultimate target was to develop a floating type water wheel model. A floating

waterwheel is basically a waterwheel with its support structure built on top of a floatable

object. The structure as a whole is anchored with anchor cables to prevent it from moving

downstream.



1.3 OBJECTIVES OF THE STUDY

Considering Sri Lankan situation of Pico hydro systems, floating type water wheel is a less

popular method. This method is suitable to obtain small amount power of average of 10W –

100W. This can be implemented to individual power consumptions (individual house required

power). Floating type water wheel method can be implemented to „no head‟ situations. It is a

principal advantage of using of this method. Then it can be used in all parts of the country with

need only flowing of water at desired flow rate. One of this project objective is introducing this

method to the Dry zone of Sri Lanka. Geographical condition of this zone, it consists of shallow

streams in flat surfaces.

The end product must be low cost and economical

The end result must be easy to manufacture.

The technology should be simple and easy to understand.

Fabrication of product must be done in locally and should use local resources.

Gain knowledge of engineering designs

Involve in economical and feasibility analysis of manufacturing process, sites selection,

Material selection

Gain both theoretical and practical knowledge on generators and power transmission.

1.4 SCOPE OF THE STUDY

At the moment there are few models which are used for water pumping. Study these

machines and develop few machines which can be used for low head applications. Undershot

water wheel with floating mechanism was the general scope of the project. Electrical

analysis, Generator selection and coupling other mechanical fabrications and development

methods also studied.



2. LITERTURE REVIEW

2.1 HISTORY OF WATER WHEELS

Waterwheels date back up to 3000 years ago and are in all probability the very first device

that man has used to do something useful for him with water power. Waterwheels were used

to grind wheat, and later on to pump water and generate electricity. Traditional waterwheels

have been established in all over the world. Mesopotamia, India, Greco-Roman, China,

Islamic culture and Medieval Europe have created water wheels to fulfill their requirements.

Generally a traditional wheel is about 4 meters in diameter and 2 meters wide. The support

structure for the waterwheel is situated on the embankment of the canal. Scoops situated

along the outer regions of the wheel. These scoops are filled with water when they are

submerged, and emptied into a catchment's area near the top of the wheel. This is typically

how a traditional waterwheel pumps water. From the rotational speed of the wheel and the

number of scoops, one can calculate how much water this wheel is pumping. This wheel

pumps around 2000 liters of water per hour.

Figure 2.1: Ancient Water Wheel

The early history of the watermill in India is obscure. Ancient Indian dating back to the 4th

century BC has used turning wheels and machine with wheel-pots attached. Irrigation water

for crops was provided by using water raising wheels, some driven by the force of the current

in the river from which the water was being raised.



The Romans used both fixed and floating water wheels and introduced water power to other

parts of the Empire. The Romans were known to use waterwheels extensively in mining

projects, they were reverse overshot water-wheels designed for dewatering mines.

Chinese water wheels almost certainly have a separate origin, as early ones there were

invariably horizontal waterwheels. By at least the 1st century AD, the Chinese of the Eastern

Han Dynasty began to use waterwheels to crush grain in mills and to power the piston-

bellows in forging iron ore into cast iron.

Cistercian monasteries, in particular, made extensive use of water wheels to power watermills

of many kinds. An early example of a very large waterwheel is the still extant wheel at the

early 13th century Real Monasterio de Nuestra Senora de Rueda, Grist mills (for corn) were

undoubtedly the most common, but there were also sawmills, fulling mills and mills to fulfill

many other labor-intensive tasks. The water wheel remained competitive with the steam

engine well into the Industrial Revolution.

The main difficulty of water wheels was their inseparability from water. This meant that mills

often needed to be located far from population centers and away from natural resources.

Water mills were still in commercial use well into the twentieth century, however.

Overshot and pitchback waterwheels are suitable where there is a small stream with a height

difference of more than 2 meters, often in association with a small reservoir. Breastshot and

undershot wheels can be used on rivers or high volume flows with large reservoirs.

The most powerful waterwheel built in the United Kingdom was the 100 hp Quarry Bank

Mill Waterwheel near Manchester. A high breastshot design, it was retired in 1904 and

replaced with several turbines. It has now been restored and is a museum open to the public.

The biggest working waterwheel in mainland Britain has a diameter of 15.4 m and was built

by the De Winton Company of Caernarfon. It is located within the Dinorwic workshops of

the National Slate Museum in Llanberis, North Wales.



2.2 TECHNOLOGY RELATED TO FLOATING TYPE WATER WHEEL

The project will be developing a floating type water wheel for Pico hydro systems. It can be

used for very low head applications such as irrigation canals. According to the historical

information there were no evidences about floating type water wheels but few similarities can

be identified undershot waterwheels.

Figure 2.2: Undershot water wheel

A vertically-mounted water wheel that is rotated by water striking paddles or blades at the

bottom of the wheel is said to be undershot. This is generally the least efficient, oldest type of

wheel. It has the advantage of being cheaper and simpler to build, but is less powerful and

can only be used where the flow rate is sufficient to provide torque.

Undershot wheels gain no advantage from head. They are most suited to shallow streams in

flat country. Undershot wheels are also well suited to installation on floating platforms.

This type of undershot wheel use with floating method will be the aim because the changing

the level of cannel will change the power generation. In floating type one blade on the wheel

will immersed in the water at the most efficient and effective level.

2.3 MODERN FEATURES OF FLOATING TYPE WATER WHEEL

Due to above impotency of floating type water wheel should be developed. Currently it has

several features that distinguish from the traditional water wheels.

1. It is floatable. Upon installation, the waterwheels are placed at the specific depth

where they will operate at maximum capability. This can easily be accomplished by

adding or removing some of the floatable material. When the water level increases or

decreases, the floating waterwheels increase or decrease with the water level, and the



waterwheels remain at the specific depth. Thus the floating waterwheels will always

operate at maximum capability.

2. It has built-in flumes. Each floating waterwheel has a built-in flume. The flume has

three sections each consists of a bottom plate and two side plates. In the first section

the side plates are converging (like a funnel). The second section is a channel (side

plates parallel to each other), and in the third section, the side plates are diverging

(like a reversed funnel). The purpose of the flume is to increase the flow rate in the

channel section, which is where the lower blades of the waterwheel are situated. The

increased flow rate in the channel has a significant increase in efficiency of the

waterwheel.

3. It does not allow water to bypass. The floating waterwheel spans across the width of a

river or stream, which means that all the water across the width is forced to flow

through the flumes of the connected floating waterwheels.

These types of waterwheels have high efficiency at part loads / variable flows and can

operate at very low heads, smaller than 1 meter. Combined with direct drive permanent

magnet alternators they offer a viable alternative for low head hydroelectric power

generation. Modern antiquated variety of the old waterwheel is the Mangal waterwheel which

was a work done by a farmer. The design of “Mangal waterwheel” has the following features.

Type: Under shot-wheel

Wheel Outer Diameter: 4 m

Wheel Width: 1.2 m

Maximum speed: 13 rpm

No. of Blades: 24 Out of these 24, 18 small and 6 bigger blades are there.

Available Head: 1.5 m

Flow rate required for the wheel: 1800 liters/ second

Power 4kw

Cost $4600



Material used for manufacture: cast iron angles, cast Iron sheets

Figure 2.3: Mangal waterwheel

2.4 PROBLEMS ENCOUNTERING AND OVERCOME

Developing the floating water wheels it has to be identified the shortcomings of the

traditional water wheels

1. Traditional waterwheels were not very efficient. They did not pump a lot of water, nor

did they generate large amounts of electricity.

2. Traditional waterwheels were also restricted to where they can be used. They were

usually put in small rivers or streams where the support structure of the waterwheel

can be placed on the embankment. It was just too expensive to build a support

structure for a waterwheel in the middle of a big river

3. Traditional waterwheels have an inherent problem and that is that their capabilities

are dependent on the water level. A waterwheel functions at its maximum capability

when the lower blades are at a specific depth under the water. When the water level

increases or decreases slightly, the waterwheel may still operate, but not at its

maximum capability. However, when the water level increases or decreases

significantly, the waterwheel may no longer operate at all.

Floating type water wheels are not popular in Sri Lanka. The development of water wheel

must be economical. To manufacturing water wheels, rural technology will be the most

suitable method.



The project will follow experimental basis development because the theoretical developments

have been not matched perfectly in previous cases.



3. THEORETICAL BACKGROUND OF THE WATER WHEEL

The methodology for a water wheel is based on theory of a flat plate placed in a fluid flow.

The consideration, as calculus hypothesis, that only one blade of the water wheel is in the

water at a time. For water wheel dimensioning, the input values were the water speed and the

needed power and the output values were the diameter and the width of the wheel, the blade

depth and the drowning ratio. After the calculus, a model with 0.60 m diameter, 0.10m depth

of blade and 0.20 m width was used to realize theory. The water wheel can be equipped with

different type of blades (straight blades - radial or inclined at 20 degree or curved blades).

The water wheel model was tested on a hydraulic channel with rectangular section at constant

flow speed for each model and drowning ratio of 80%. The tests show a better behavior of the

water wheel equipped with curved blades comparing to the water wheels equipped with

inclined or radial straight blades and the influence of the flow velocity on water wheel

efficiency.

3.1 NOMENCLATURE

Table No. 3.1: Nomenclature

Parameter Units Description

D M water wheel diameter

L M water wheel width

B M Depth of water wheel

vam m/s upstream flow velocity

k

-

extraction coefficient

α Deg incidence angle

CR - drag coefficient

CP - lift coefficient



θ [deg] angle between zero active

and full active position of

the blade

g m/s2 gravity

ρ kg/m3 density

v m/s velocity

Subscripts and Superscripts

r relative direction

t tangential direction

3.2 THEORETICAL APPROACH

For the water wheel theoretical analysis, the theory of the flat plate placed in a fluid flow.

The basic hypothesis that it is that there is only one active blade at a time. i.e. water wheel

consist of six straight type blades. In these conditions the velocities and the forces on the

water wheel blade are presented in Figure No. 3.1.

Figure 3.1 Forces On Water Wheel Blade



Figure 3.1 shows the relative and tangential velocities and the forces generated by the water

on the blade. Following Conjunctive relations between geometric and energetic

characteristics theory is based on fluid characteristics on flat plate placed in a fluid flow.

1. The submerged surface of the blade

S=L x (D/2) x (1-cosθ/sinα) (Eq.3.1)

2. The advanced (lift) force

P=Cp x (ρ/2) x vr 2 x S (Eq.3.2)

3. The dragged force

R= CR x (ρ/2) x vr 2 x S (Eq.3.3)

4. The Consequence force

F= √(P2+R

2) (Eq.3.4)

5. The useful force and its angle

Fu= F x cosε (Eq.3.5)

ε= arctan (CR/ CP) – (α-γ) (Eq.3.6)

Where γ is the relative velocity angle.

6. The useful couple

M =Fu x (D/4) x (1+Cosθ/Sinα) (Eq.3.7)

Where θ is the angle between the zero action position and the maximum load position of the

blade.

7. The instantaneous power and the average power of the water wheel

Nu= M x ω= Fu x vt (Eq.3.8)

Nmed =Ki Σ(Nu/n) (Eq.3.9)



where n is the number of the calculus points between the zero action position and the

maximum load position of the blade and ki is a coefficient of influence that take into account

the blade from the backward of the active blade. For undershot water wheel type Ki is 1.6.

8. Maximal power of the flow

Nmax = (ρ/2) x Smax x vam3 (Eq.3.10)

Where Smax = L. h is the maximum submerged surface of the blade and h is the drowning

ratio.

9. Hydraulic efficiency of the water wheel

η= Nmed/ Nmax (Eq.3.11)

10. Angular speed

ω= 4vt/[D(1+ Cosθ/Sinα)] (Eq.3.12)

11. Rotational speed

nmed= (30/πn) x Σ ωj (Eq.3.13)

The values of drag (CR) and lift (CP) coefficients for the flat plate placed in a fluid flow, was

considered according to appendix A 1.

3.3 DIMENSIONS OF THE MODEL

To realize and testing of performance of above theoretical stuff of water wheel designing,

design and fabricate a water wheel with following dimensions.

Outer diameter of water wheel 0.60 m

Width of water wheel 0.20 m

Blade depth of water wheel 0.10 m



Figure.3.2 Solid Works Model of a Water Wheel

3.4 ASSUMPTIONS ON THEORETICAL ANALYSIS

1. Only one blade of the water wheel is in the water at the time.

2. Flow of water is steady, uncompressible and laminar.

3. There is no energy loss due to friction and other circumstances.

4. Velocity of flow obtains as an average value of velocity profile of water flow.

5. Consider six number of calculus points for the analysis.

3.5 THEORETICAL CALCULATION

According to (Eq.3.1) to (Eq.3.13) equations,

By geometrical relationship in the Fig No.3.1

θ = cos-1

[{(0.5 x D) – (B x h)}/ (0.5 x D)] (Eq.3.14)

α = (90 – θ ) + θ x (m / m+1) (Eq.3.15)

Where m is no. calculus points.

(13) Given that θ = cos-1[{(0.5 x 0.60) – (0.10 x 0.80)}/ (0.5 x 0.60)]

= 42.83 degrees

(14) Given that for first calculus point (m= 1)



α = (90 – θ ) + θ x (m / m+1)

= (90 – 42.83) + (1/7)

= 53.29 degrees

Similarly for all calculus points, i.e. 1≤m ≤ 6

Table No. 3.2: α and m Values

m α (Deg.)

1 53.29

2 59.40

3 65.52

4 71.64

5 77.76

6 83.88

For first calculus point,

The submerged surface of the blade, S = L x (D/2) x [1-(cosθ/sinα)]

= 0.20 m x (0.60 m /2) x (1-cos(42.83)/sin(53.29))

= 0.005112 m2



Similarly for other calculus points, 1≤m ≤ 6

Table No. 3.3: m and S Values

m S (m2)

1 0.005112

2 0.008884

3 0.011655

4 0.013641

5 0.014977

6 0.015748

3.5.1 AVERAGE VELOCITY OF WATER FLOW

The average velocity of water flows, Vam (velocity profile) as 0.605 ms-1

. This velocity value

obtains from the testing site at Belihul-Oya.

From Geometry of Fig No. 3.1,

Vr = √( Vam2 – 2 x Vam x Vt x sin α + Vt

2) (Eq.3.16)

Vt = (Vam x sin α) x 0.5 x [1+( cosθ/sinα)] (Eq.3.17)

tan γ = (Vt x cosα) / (Vam - Vt x sin α) (Eq.3.18)



For all calculus points, i.e. 1≤m ≤ 6

Table No. 3.4: Values For m, Vam, Vt, Vr, γ and ε Parameters

3.5.2 CALCULATION OF FORCES

Consider only first calculus point, i.e. m = 1

The advanced (lift) force, P = Cp x (ρ/2) x vr 2

x S

= 2.19 x (1000/2) x 0.716631 x 0.005112

= 2.874469 N

The dragged force, R = CR x (ρ/2) x vr 2

x S

= 1.4 x (1000/2) x 0.716631 x 0.005112

= 1.83756 N

The Consequence force, F = √ (P2+R

2)

= √ (2.874469 2+1.83756

2)

= 3.411627 N

m Vam(m/s) Vt(m/s) Vr(m/s) γ (Deg.) ε (Deg.)

1 0.605 0.4643251 0.716631 50.01660484 29.32050865

2 0.605 0.4822204 0.658933 52.26816894 34.28714033

3 0.605 0.4971486 0.59304 53.47952693 39.90872901

4 0.605 0.5089396 0.519943 52.73286269 42.57879986

5 0.605 0.517459 0.44087 47.84567264 41.45912569

6 0.605 0.5226099 0.357368 33.12684928 29.78358823



The useful force and its angle, Fu = F x cosε

= 3.411627 x cos 29.32050865

= 2.974578 N

The useful couple, M =Fu x (D/4) x (1+Cosθ/Sinα)

= 2.974578 x (0.60/4) x (1+Cos42.83/Sin53.29)

= 0.854362 Nm

The instantaneous power, Nu = Fu x vt (= M x ω)

= 2.974578 x 0.4643251

= 1.381171 W

For all calculus points, i.e. 1≤m ≤ 6.

Table No. 3.5: Values For P, R, F, Fu, M and Nu Parameters

m P(N) R(N) F(N) Fu (N) M(Nm) Nu (W)

1 2.874469 1.83756 3.411627 2.974578 0.854362 1.381171

2 3.278687 2.89296 4.372529 3.612691 1.003571 1.742114

3 2.21355 2.828425 3.591628 2.755021 0.746229 1.369655

4 1.622576 2.987015 3.399267 2.503041 0.665553 1.273897

5 0.887853 2.63445 2.780037 2.083439 0.547023 1.078094

6 0.321791 1.930746 1.957378 1.698823 0.442765 0.887822

Σ Nu

7.732752



The average power of the water wheel, Nmed =Ki Σ(Nu/m)

= 1.6 x Σ(Nu/m)

= (1.6/6) x (7.732752)

= 2.062067 W

Maximal power of the flow:, Nmax = (1000/2) x 0.2 x 0.8 x 0.6053

= 40.96 W

Hydraulic efficiency of the water wheel, η = Nmed/ Nmax

= 2.062067/ 40.96

= 5.034343871%

Angular speed, ω = 4vt/[D(1+ Cosθ/Sinα)]

= (4 x 0.4643251) / [0.60 x (1+ Cos 42.83 /Sin

53.29)]

= 1.616611959 rad/ s

For all calculus points, i.e. 1≤m ≤ 6,

Table No. 3.6: m and ω Values

m Angular velocity, ω (rad/s)

1 1.616611959

2 1.735913855

3 1.835435143

4 1.914041783

5 1.97083806

6 2.005176783

Σ ωj 11.07801758



Rotational speed, nmed = (30/πm) x Σ ωj

= (30/π x 6) x (11.07801758)

= 17.63121258 rpm

3.6 THEORETICAL RESULTS

Analysis that is only for six blade straight type water wheel with outer diameter 0.60 m,

width 0.20 m and depth of blade 0.10 m.

Table No. 3.7: Theoretical Results for 6 Blade Straight Type Water Wheel

Parameter Result

The useful couple, M 0.854362 Nm

The average power of the water wheel, Nmed 2.062067 W

Maximal power of the flow:, Nmax 40.96 W

Hydraulic efficiency of the water wheel, η 5.034343871%

Rotational speed, nmed 17.63121258 rpm

3.7 DESIGN OF BREAKING LOAD TEST APPARATUS

In performance testing a small “leather strip” were used to break load test. Assumed that;

1. Can be apply V- belt theory to design power transmission mechanism.

2. According to analysis, maximum power of water wheel is 40.96 W.

3. Maximum rotational speed of water wheel (RPM) is 50 RPM (considering speed up

of 12 blade cases)



3.7.1 POWER TRANSMISSION BY A V- BELT

Figure No. 3.3: Forces on Belt Drive

Power Transmitted by a belt drive

Power Transmitted, P = (T1-T2) x V (Eq.3.19)

Where: - T1= Tension in the tight side in N

T2= Tension in the Slack Side in N

V= Velocity of the belt in ms-1

r = Radius of the pulley

V= r x ω = r x r.p.m.x 2π/60 (Eq.3.20)

Torque exerted on driving pulley (τ)

τ = (T1-T2) x r (Eq.3.21)

The ratio of Driving Tension for V-belt

2.3 log (T1/T2) = μθ cosecβ (Eq.3.22)

Where: μ:- Coefficient of the friction between the belt and sides of the groove.

Drive Pulley

Tight Side (Tension: T1) Slack Side (Tension: T2)

Direction of

Rotation



θ:- Angle of contact in radians.

β:- Groove angle

Assume that total power developed by the turbine is transmitted by the belt.

Select Type A belt (According to Appendix A 2)

Diameter of the drive pulley is 180 mm

For a belt drive from equation No Eq.3.19, Eq.3.20, and Eq.3.21

P= (T1-T2) r ω

40.96 W = (T1-T2)*0.09*50*2π/60

(T1-T2) = 86.92N (Eq.3.23)

Assume: μ= 0.3.

θ= 1800= π rad

From Appendix A 2

2β= 320 hence β= 16

0

2.3 log (T1/T2) = μθ cosecβ

2.3 log (T1/T2) = 0.3 x π cosec160

T1/T2 = 30.66

T1 = 30.66T2 (Eq.3.24)

T1 = 89.851 N

T2 = 2.931 N

According to T1 and T2 values maximum breaking load tension is 89.851 N (9.159 kg). It is

proved that tight side tension can be measured by 25 kg spring balance.



4. PREFOMENCE TESTING OF WATER WHEEL – 1st SERIES OF

TESTING

As the first step of the testing of power output of water wheel there was a suitable site in

Belihul-Oya. Then the place was arranged to do the experiment.

Figure 4.1: Testing Apparatus

25kg spring balance was used to measure the tight side tension (T1) and bucket was attached

to the slag side of the rope. Then by adding sand to the bucket tension of the slag side (T2)

was changed. At that time reading of the spring balance was obtained and the rotational speed

of the water wheel was taken by digital tachometer. The weight of the sand was obtained by

electronic balance. There are assumptions those have given below when the continuing this

testing.

1. Friction coefficient between the rope and the pulley remain unchanged during the

testing.

2. Water flow rate trough the water wheel remain unchanged during the testing

3. Self weight of the spring balance and bucket was negligible

4. Drowning ratio of blades was constant.

5. Drive shaft was proper aligned and there was no loss due to improper alignment.

6. During the testing, blades was not sagging or hogging due to impact force of water.

7. Using rope was not given any strain due to tension

8. Spring balance, electronic balance and Digital Tachometers were in proper calibrated

conditions.

9. Contact angle of the belt is 1800 and it remains constant during the testing.



Testing procedure continued to three types of blades and two different numbers of blades (6

and 12)

Figure 4.2: Straight Type Blade

Figure 4.4: Curve Type Blades

Those blades were drawn in the water about 80% and assumed the flow speed was constant

when the each part of the testing.

Figure 4.3: Inclined Blade at Angle 20°

200



4.1 PERFORMANCE TESTING OF SIX BLADE STRAIGHT TYPE WATER

WHEEL

DATA:

Diameter of the Pulley = 18 cm

OBSERVATIONS:

Table No.4.1: Observation Values for Six Blade Straight Type Water Wheel

Flow Speed of water = 0.605 ms-1

SPECIMEN CALCULATIONS:

Consider the first set of data from Table No.4.1

From Equation No.(19)

P = (T1- T2) x r x RPM x (2π/60) W

P = (0.5- 0.075) kg x 9.81 ms-2

x9 x 10-2

m x 18.42 x (2π/60) rad/s

P = 0.7238 W

Tight Side

Tension (T1) /(Kg)

Slack Side Tension

(T2) / (Kg) RPM

0.5 0.075 18.42

1 0.141 16.92

1.5 0.33 15.94

2 0.191 11.32

2.5 0.534 10.31

3 0.672 3.54

3.5 0.692 2.24



RESULTS:

Table No.4.2: RPM Vs Power for Six Blade Straight Type Water Wheel

RPM Power(W)

21.03 0

18.42 0.7238

16.92 1.343797

15.94 1.724306

11.32 1.893325

10.31 1.874055

3.54 0.76195

2.24 0.581548



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4.1



4.2 PERFORMANCE TESTING OF TWELVE BLADE STRAIGHT TYPE

WATER WHEEL

OBSERVATIONS:

Table No.4.3: Observation Values for Twelve Blade Straight Type Water Wheel

Tight Side

(T1) (Kg)

Slack Side (T2)

(Kg) RPM Power(W)

45.92 0

1 0.21 42.9 3.133463

1.5 0.308 41.67 4.592402

2 0.54 40.7 5.493984

2.5 0.632 37.14 6.414442

3 0.928 33.34 6.386979

3.5 1.058 27.94 6.308298

4 1.078 27.17 7.340235

4.5 1.364 18.85 5.46547

5 1.592 0 0


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3.1



RESULTS:

Table No.4.4: RPM Vs Power for Twelve Blade Straight Type Water Wheel

RPM Power(W)

45.92 0

42.9 3.133463

41.67 4.592402

40.7 5.493984

37.14 6.414442

33.34 6.386979

27.94 6.308298

27.17 7.340235

18.85 5.46547



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4.2



4.3 PERFORMANCE TESTING OF SIX BLADE INCLINED TYPE WATER

WHEEL

OBSERVATIONS:

Table No.4.5: Observation Values for Six Blade Inclined Type

Water Wheel

Tight Side (T1)

(Kg)

Slack Side (T2)

(Kg) RPM

0.5 0.072 32.42

1 0.138 30.07

1.5 0.126 13.87

2 0.186 11.82

2.5 0.53 10.31

3 0.672 3.57

3.5 0.356 1.52




RESULTS:

Table No.4.6: RPM Vs Power for Six Blade Inclined Type Water Wheel

RPM Power(W)

35.87 0

32.42 1.282912

30.07 2.396519

13.87 1.76199

11.82 1.982416

10.31 1.877868

3.57 0.768407

1.52 0.441841



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4.3



4.4 PERFORMANCE TESTING OF TWELVE BLADE INCLINED TYPE

WATER WHEEL

OBSERVATIONS:

Table No.4.7: Observation Values For Twelve Blade Inclined Type Water Wheel

Tight Side (T1)

(Kg)

Slack Side (T2)

(Kg) RPM

1 0.12 34.77

1.5 0.18 32.22

2 0.372 30.11

2.5 0.486 27.9

3 0.684 26.7

3.5 0.844 24.81

4 1.056 20.65

4.5 1.202 21.26

5 1.368 18.59

5.5 1.53 16.87

6 1.704 15.24

6.5 1.842 14.14


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3.3



RESULTS:

Table No.4.8: RPM Vs Power For Twelve Blade Inclined Type Water Wheel

RPM Power(W)

38.89 0

34.77 2.828964

32.22 3.932236

30.11 4.532161

27.9 5.195218

26.7 5.717286

24.81 6.092492

20.65 5.620798

21.26 6.482672

18.59 6.242598

16.87 6.192211

15.24 6.053261

14.14 6.089604



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4.4



4.5 PERFORMANCE TESTING OF TWELVE BLADE CURVED TYPE

WATER WHEEL

OBSERVATIONS:

Table No.4.9: Observation Values for Twelve Blade Curved Type Water Wheel

Tight Side (T1)/

(Kg)

Slack Side (T2)

/(Kg) RPM

1 0.29 32.33

1.5 0.454 31.33

2 0.718 29.3

2.5 0.846 28.8

3 1.06 26.2

3.5 1.212 25.11

4 1.378 25.25

4.5 1.546 24.19

5 1.768 21.28

5.5 1.902 21.32


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RESULTS:

Table No.4.10: RPM Vs Power for Twelve Blade Curved Type Water Wheel

RPM Power(W)

34.63 0

32.33 2.122287

31.33 3.029927

29.3 3.472928

28.8 4.404211

26.2 4.699408

25.11 5.311814

25.25 6.121167

24.19 6.606729

21.28 6.358916

21.32 7.092323



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4.5



4.6 COMMENTS

1. During testing it was difficult to keep the water flow speed at a constant value. It was

difficult to compare the test results directly. For an example 12 blade straight type was given

maximum value of power of 7.367W at 29.06 r.p.m. At that moment flow velocity was

0.62m/s also 12 blades inclined and curve type were given maximum power and relevant

r.p.m. values 6.357W at 19.93 r.p.m. and 7.034W at 18.08r.p.m.There relevant flow

velocities were 0.605m/s and 0.54m/s. It is clearly show that curve type water wheel was

given relatively high power with comparing other two cases in low water flow velocity. Also

inclined type was given relatively high power with comparing straight type case in low water

flow velocity.

2. Friction coefficient between pulley and the rope may change due to generated heat due to

friction between pulley and the rope.

3. There may be errors occurred in slack side when the sand taken off from bucket.

4. It was difficult to get r.p.m. values because the water wheel drive shaft coupled with pulley

was not proper aligned. Average values for r.p.m were considered.

5. It was difficult to changed the drowning ratio and obtain constant value.

6. There may be error due to self weights of spring balance and buckets were neglected.

7. The maximum power and relative r.p.m were obtained. from power vs r.p.m. curve for

relevant water wheel. The power vs r.p.m. curve is important characteristic of any type of

water wheel when comparing each other.

8. The average water flow velocity was derived from surface flow velocity .In real situations

it is suitable to consider velocity profile of water flow and respect water flow velocities.



4.7 DISCUSSION

1. The theoretical analysis was based on 6 blades straight type water wheel. It is suitable to

analyze both theoretical and performance testing values to realize availability of theoretical

stuff.

Table No.4.11: Theoretical and Testing Results of Average Power and R.P.M of Water

Wheel

Average power (W)

R.P.M.

Theoretical analyze 2.062 17.631

Experimental analyze 1.952 11.2

There is about 5.33% deviation between theoretical and experimental values of power. There

is 36.48% deviation between theoretical and experimental values of R.P.M. These small

deviations may occur due to errors during testing. It can be prove that theoretical stuff for 6

blades straight type water wheel can be used to design purposes of it. When consider more

than 6 blades, it is need to apply an efficiency factor.



2. Comparing testing values (highest power value on curve) of above various type of water

wheel

Table No.4.12: Compare Of Testing Results for Water Wheels

From the experimental results prove that 12 blades water wheels have higher average power

compare with 6 blades water wheels. It is approximately 2.5-3 times factor. The results are

difficult to compare directly due to variation of flow velocity. These results clearly show if

number of blades are increasing its output power also increasing.

3. Straight type is lowest efficiency water wheel. Relative to low flow velocity 12 blades

curve type water wheel give some amount of higher power. It is prove that curve type blades

give higher efficiency than other two types of blades.

4. For these models most efficiency points R.P.M. varying between 20r.p.m. to 35 r.p.m. The

generator should be tackled with these low speeds. (Gearing or power transmission may be

caused to loss water wheel power. There may be probability to stop the water wheel at

loading position of generator).

Straight Inclined Curved

6 12 6 12 12

Flow

velocity(m/s) 0.605 0.62 0.58 0.605 0.54

Average

power(W) 1.952 7.362 2.415 6.357 7.034

R.P.M. 11.20 29.06 19.23 19.06 18.08



5. During the testing it is difficult to change drowning ratio but increasing drowning ratio up

to 100% will increase the power output. If it above 100% also it is decreasing output power.

Practically to this phenomena and it shows 100% drowning ratio is best point for the Water

wheels.

6. Theoretical analysis show that depth of blades and width of blades are increasing, also

efficiency of water wheel is increasing.



5. THEORETICAL DESIGN OF FLOATING TYPE WATER WHEEL

According to the first series of testing of water wheel results, it concluded that curved type

blades give high performance of mechanical power with comparing other types, straight and

inclined types. It concluded that inclined type of blades give improved performance of power

rather than straight (radial) type. Based on that results and other obtained results such as

power improvement factor; six blades to twelve blades transforming, the next model was

prepared for the testing and prototype.

5.1 DESIGN PROCEDURE

At this series of testing, The relationships between diameter of water wheel, width of blades,

depth of drowning of blades and type of curves were considered.

1. Changing Diameters of water wheel:

To obtain relationship of diameter of water wheel, The inner diameter was changed which is

the diameter of blades bolted wheel. For this requirement, two rims were used (Small: Motor

bike rim and Large: Bicycle rim) with different diameters.

2. Changing width of blades:

Two different widths for blades were considered and other factors were constant.

3. Changing drowning depth of blades:

Two different depths for blades were considered and other factors were constant.

4. Changing type of curve:

Two different curved blades were considered and other factors were constant.

5.1.1 DIMENSIONING OF WATER WHEELS MODELS

Curve Model 1 (C-1)

Width of blade = 40 cm

Length of blade = 20 cm

Mathematical equation of curve => Y= -32.006X2+1904.4X-28306



Curve Model 2 (C-2)



Mathematical equation of curve => Y= -59.059X2+35.35.6X-52534

Curve Model 3 (C-3)




Curve Model 4 (C-4)




Rims

Diameter of Small rim, R-1 = 50 cm

Diameter of Large rim, R-2 = 66.5 cm

Mathematical equations were derived by using MATLAB 7.0® software.

5.2 THEORETICAL CALCULATIONS FOR WATER WHEEL MODELS

Power and rotational speeds calculations are based on previously discussed theoretical

approach for water wheel and test results. Design calculations for six blades were conducted

and it analyzed to twelve blades and for inclined curve blades.



According to chapter 3, from Eq.3.1 to Eq.3.13

Model-1 specification:

Blade = C-1

Blade width (L) = 40 cm


Effective depth of blade (B) = 14 cm

Inner diameter of water wheel, R-1 (D1) = 50 cm

Effective Diameter of water wheel (D) = (50+14x2) cm

= 78 cm

Let drowning ratio is 0.9

(13) Given that θ = cos-1[{(0.5 x 0.78) – (0.14 x 0.90)}/ (0.5 x 0.78)]

= 47.4 degrees

(14) Given that for first calculus point (m= 1)

α = (90 – θ ) + θ x (m / m+1)

= (90 – 47.4) + (1/7)

= 49.37 degrees



Similarly for all calculus points, i.e. 1≤m ≤ 6

Table No. 5.1: α and m Values for M-1

m α (Deg.)

1 49.37

2 56.15

3 62.92

4 69.69

5 76.46

6 83.23

For first calculus point,

The submerged surface of the blade, S = L x (D/2) x [1-(cosθ/sinα)]

= 0.40 m x (0.78 m /2) x (1-cos(47.4)/sin(49.37))

= 0.016866 m2

Similarly for other calculus points, 1≤m ≤ 6

Table No. 5.2: m and S Values for M-1

m S (m2)

1 0.016866

2 0.028841

3 0.037394

4 0.043397

5 0.04738

6 0.049658



5.2.1 AVERAGE VELOCITY OF WATER FLOW

The average velocity of water flow, Vam (velocity profile) as 0.6 ms-1

.

From Eq.3.16 ,Eq.3.17 and Eq.3.18

For all calculus points, i.e. 1≤m ≤ 6 values for Vr, Vt, ε and γ parameters were obtained.

Table No. 5.3: Values For m, Vam, Vt, Vr, γ and ε Parameters for M-1

5.2.2 CALCULATION OF FORCES

Consider only first calculus point, i.e. m = 1

The advanced (lift) force, P = Cp x (ρ/2) x vr 2

x S

= 1.1x (1000/2) x 0.9734212 x 0.016866

= 8.789927 N

The dragged force, R = CR x (ρ/2) x vr 2

x S

= 1.3 x (1000/2) x 0.9734212 x 0.016866

= 8.789927 N

m Vam(m/s) Vt(m/s) Vr(m/s) γ (Deg.) ε (Deg.)

1 0.60 0.4307716 0.973421 45.76885436 46.1579245

2 0.60 0.4522133 0.881709 48.29959659 48.28694119

3 0.60 0.4701798 0.730366 49.72561703 50.38325197

4 0.60 0.4844205 0.529031 49.09283049 49.55033034

5 0.60 0.4947367 0.294738 44.2261493 44.44342752

6 0.60 0.5009846 0.099823 29.95052253 29.41566774



The Consequence force, F = √ (P2+R

2)

= √ (8.7899272+8.789927

2)

= 13.60791 N

The useful force and its angle, Fu = F x cosε

= 13.60791 x cos 46.1579245

= 9.425835 N

The useful couple, M =Fu x (D/4) x (1+Cosθ/Sinα)

= 9.425835 x (0.78/4) x (1+ cos(47.4)/sin(49.37))

= 3.477351 Nm

The instantaneous power, Nu = Fu x vt (= M x ω)

= 9.425835 x 0.4307716

= 4.060382 W



For all calculus points, i.e. 1≤m ≤ 6

Table No. 5.4: Values For P, R, F, Fu, M and Nu Parameters for M-1

m P(N) R(N) F(N) Fu (N) M(Nm) Nu (W)

1 8.789927 10.38809 13.60791 9.425835 3.477351 4.060382

2 11.21056 16.70373 20.11694 13.38582 4.7379 6.053248

3 8.178368 16.45647 18.37665 11.71785 4.022241 5.509499

4 3.947386 10.93122 11.62211 7.540191 2.531643 3.652623

5 0.926089 3.910153 4.018325 2.868852 0.948943 1.419326

6 0.061853 0.482454 0.486403 0.423695 0.138941 0.212265

Σ Nu

20.90734

The average power of the water wheel, Nmed =Ki Σ(Nu/m)

= 1.6 x Σ(Nu/m)

= (1.6/6) x (20.90734)

= 5.575292 W

Maximal power of the flow:, Nmax = (1000/2) x 0.4 x 0.9 x 0.603

= 38.88 W

Hydraulic efficiency of the water wheel, η = Nmed/ Nmax

= 5.575292 / 38.88

= 14.33974192 %



Angular speed, ω = 4vt/[D(1+ Cosθ/Sinα)]

= (4 x 0.4307716) / [0.78 x

(1+cos(47.4)/sin(49.37)]

= 1.16766525 rad/ s

For all calculus points, i.e. 1≤m ≤ 6,

Table No. 5.5: m and ω Values for M-1

m Angular velocity, ω (rad/s)

1 1.16766525

2 1.277622634

3 1.369758477

4 1.442787577

5 1.495691251

6 1.527731549

Σ ωj 8.281256737

Rotational speed, nmed = (30/πm) x Σ ωj

= (30/π x 6) x (8.281256737)

= 13.18002945 rpm



Dimensions of testing models have been showed in Table No. 5.6.

Table No. 5.6: Specification Summery of Models

Model

No.

Curve

type

Blade width

(L) (cm)

Length

of blade

(cm)

Effective depth

of blade (B)

(cm)

Inner

diameter of

water wheel,

(RIM) (cm)

Effective

Diameter of

water wheel

(D) (cm)

M-1 C-1 40 20 14 50 78

M-2 C-4 60 28 11 66.5 88.5

M-3 C-2 40 20 16 50 82

M-4 C-3 40 28 11 50 72

M-5 C-4 60 28 11 50 72

For Model M-2 to M-.5 were analyzed similarly. Assumed that average flow velocity at

blades centre of buoyancy is 0.6 ms-1

and water wheel has six blades.

Table No. 5.7: Output Summery of Models

Model No. Average Power,

Nmed (W)

Maximum

Power, Nmax (W)

Rotation Speed,

RPM

Hydraulic

Efficiency, %

M-1 5.575292 38.88 13.18002945 14.33974192

M-2 17.62107 58.32 12.03422653 30.21445302

M-3 12.25286 38.88 12.40772887 31.51456112

M-4 1.963807 38.88 14.5281845 5.050943098

M-5 2.947916 58.32 14.5281845 5.054724844

For twelve blade case power improvement factor can be get as 2.5-3 by according to the first

series test results analysis. For justification as power improvement factor 2.5 was taken.



Rotation speed differs slightly in the case of twelve blades. It is ultimately focused output

power amount from the water wheel. Modified average power values for models are given

Table No. 5.8.

Table No. 5.8: Output Summery of Models

Model No. Estimated average power (W)

M-1 13.94

M-2 44.05

M-3 30.63

M-4 4.91

M-5 7.37

5.3 CONCLUSION ON THEORETICAL ANALYSIS

1. Changing Diameters of water wheel:

Comparing M-1 and M-2 models, their difference is only effective diameter. Small diameter

model (M-1) gives higher power than lager diameter model

2. Changing width of blades:

Comparing M-4 and M-5 models, their difference is only blade width. Large width (M-5)

model gives higher power than small width model

3. Changing drowning depth of blades:

Comparing M-1 and M-4 models, Large effective depth model (M-1) gives higher power than

small effective depth model.

4. Changing type of curve:

Comparing M-1 and M-3 models, M-3 gives high power rather than other model.M-3‟s curve

type gives extra effective depth to the water wheel.



6. MECHANICAL DESIGN OF FLOATING TYPE WATER WHEEL

6.1 DESIGN CALCULATIONS FOR SHAFT

The shaft is used for power transmitted from water wheel to the power generator. It bears

water wheel above from desired level and connects with floating type structure through two

bearings. According to the design shaft is critical component and it must be exist without

excessive bending and shearing. There are both bending and twisting moment exists during

the operation. Shaft must be design with considering bending and twisting moment

application.

SHAFT DESIGN DATA:

Shaft material = 40 C 8 carbon steel

Maximum rotation speed, ω = 30 rpm

Maximum Power Transmitted, P = 60 W

Yield strength, σ = 320 Mpa

Maximum allowable strength, τ = 42Mpa

Diameter of the drive pulley = 180mm

Weight of the drive pulley, w = 2.5 kg

Weight of the shaft = 4.6 kg



Figure 6.1: Layout diagram of Input shaft

6.1.1 VERTICAL FORCES CALCULATION

According to chapter 03 3.7.1 section tensions of pulleys power transmission cord can be

calculated as;

Tension in the tight side, T1 =219.22 N

Tension in the slack side, T2 =7.15N

Total vertical load acting on the pulley,

WT = T1+ T2+w

= 219.22+7.15+24.525

= 250.895 N

Total weight of the water wheel = 34 kg

Maximum weight model is M-5.

Assume that weight of the water wheel acting on center of the water wheel axis.



Total vertical load acting on the water wheel = 333.54 N

Shaft weight acting on 600mm from R2 acting point

6.1.2 HORIZONTAL FORCE CALCULATION

Water flow‟s impact forces on turbine blade act horizontal direction at center of blade. Shaft

produces reaction force to impact force. Its direction is opposite direction to water flow.

Water flow‟s impact forces = Mass flow rate x Acceleration

= (Area (A) x Velocity (ρ) x Density (ρ)) x

Instantaneous Velocity change (V-0)

= A x ρ x V2

Area (A) is defined as one blade‟s area immersed at time.

Considering M-5 model‟s one blade‟s area = 60 x 28 cm2

= 1680 cm2 (0.168 m

2)

Water flow‟s impact forces = 0.168 x 1000 x 0.62

= 60.48 N

Figure 6.2: Vertical Load diagram of shaft



Figure 6.3: Horizontal Load diagram of shaft

Considering equilibrium and taking moments,

R1 + R2 = (333.54+250.895+45.126 )N

R1 = 494.92 N

R2 = 134.641 N

R3 + R4 = 60.48 N

R3 = 30.24 N

R4 = 30.24 N

Considering x Distance from R1 force;

Figure 6.4: bending moment diagram of shaft

x

R2

R



Considering Bending Moment at Distance x;

M = R2*x

If distance x is 500mm

M = 134.641 * 0.5

= 67.3205 Nm


M = (134.641*0.6)-(333.54*0.1)

= 47.4306 Nm


M = (134.641*1)-(333.54*0.5)-(45.126*0.4)

= -50.1794 Nm


M = (134.641*1.2)-(333.54*0.7)-(45.126*0.6)

+ (494.92*0.2)

= -0.0004 Nm



Figure 6.5: Vertical bending moment diagram of shaft

Figure 6.6: Horizontal bending moment diagram of shaft

C B

15.12 Nm

mmmmmmmm

mmmmmm

Nmm

D



Figure 6.7: Resultant bending moment diagram of shaft

Resultant bending moment = {(HBM) 2+ (VBM)

2}

1/2

= 68.99 Nm

Torque transmitted by the shaft given from the relation,

T= Tmax =P*60/2 ΠN

= 60*60/(2Π*30)

=19.098Nm

Te = (M2 + T

2)1/2

according to maximum shear stress theory

Maximum bending moment at 500 mm from B end.

M = 68.99Nm

T = 19.098Nm

Te = 71.58 Nm

Te = (Π/16). τ.d3



The shaft made by 40 C 8 carbon steel

τ = 42Mpa

Te < (Π/16). τ.d3

D > 20.55 mm

According to the standard sizes of shafts and considering key way and bearings, shafts

diameter was selected as 1” (25.4 mm).

6.2 BEARING CALCULATIONS FOR SHAFTS

Reactions on the bearings are calculated under input shaft calculations.

RC = (R12+R3

2)1/2

RC = (494.92 2+30.24

2)

1/2

RC = 495.84 N

RB = (R22+R4

2)1/2

RB = (134.6412+30.24

2)1/2

RB = 137.99 N

Applying

Lh = (1000000/60*n)*[C/P]k

For deep groove ball bearings

Lh - Life of the bearings in operating hours

C - Basic dynamic load ratings in Newton (N)

P - Equivalent dynamic load on the bearings (N)

K - An exponent which is 3 for ball bearings

n - Speed in r.p.m



Assumed that all the ball bearings have a life of minimum 10000 operating hours.

From equation

Lh = (1000000/60*n)*[C/P]k

100000 = (1000000/60*30)*[C/60]3

C = 338.773N

From the bearing tables and according to the standard size of shaft was selected the following

deep groove ball bearing with bore 25mm and outside diameter 52mm.

P205 with C = 338.773 N

P205 Y type bearings with self alingment were selected for proper alingment of shaft.

6.3 DESIGN OF BLADE HOLDING RIM

It is requred proper circle for holding blades. If neither it may cause high enery loss and

excessive wearing of bearings. For this requriments and limits Motor bike rims and bicycle

rims were used for obtain proper circular shape. These components withstand to high impact

forces and resistive corrosion.( These rims are coated with Nickal and chromium mixture).

They are available in local marcket in different sizes.

6.4 DESIGN OF BLADES

Blades are very important component of the design. It shoud be reliable with high impact

forces and envionmental changes such as flooding situation. Its deform charecteristics during

the operation should be minimum to minimize powewr loss. Weight of the blades should be

minimized. It should keep its curve shape for long time.Gauge 19 (0.5mm thikness) steel

plate with anti-corroded film were selected.



6.5 DESIGN OF FLOTING STRUCTURE

Floating structure should be light weighted and strong enough to bear dead load and impact

forces. it should be exist in wet enviroment with minimizing corrode.

25 leters painted four barrels with 28cm diameter and 46cm long were used as floating

structure.

6.5.1 CALCULATIONS FOR FLOATING STRUCTURE

Overall weight of the structure should be less than the upthrust from floating structure,

sturucture may float on water.

Most weighted model M-5 water wheel was used for this calculations. Other water wheels

have lesser weight than M-5.

Self weight of the M-5 water wheel = 33 kg

Shaft weight = 4..6 kg

Other accessories of structure‟s weight = 12 kg

Two Couple of welded barrels with welded platform weight = 30 kg

Total self weight = 33+4.6+12+30

=79.6 kg

Upthrust force (weight) from barrels contained air = Volume x Density of water x

Gravitional acceleration

= 0.1 * 1000

=100 kg



This 100 kg express when all barrels totally immersed in water. According to the results

barrels may not completely immersed in water.

Figure 6.8: Designed model of floating type water wheel



7. MANUFACTURING TECHNIQUES FOR FLOATING STRUCTURE

AND WATER WHEEL

The development of water wheel mainly focused on rural villagers. Development should be

easy to manufacture and simply design. It should be low cost during manufacturing and

maintenance. It considers used materials in design should be available in local market.

7.1 MANUFACTURING OF BLADES

The design, it required curved inclined type blades. It was manufactured from rolling

machine (For circular bending) and shear cutting machine (For bend 90o bends and C-3). This

procedure was used for obtain different type of curved types in different sizes to testing

purposes.

Suggestion: Rolling and shear cutting operations during the manufacturing of blades spend

higher amount of money. If it can take barrels of given sizes and cutoff blades from them it

will be easy and low cost. These barrels are available in local market.

Figure 7.1: Different types of Blades



7.2 MANUFACTURING OF BLADE HOLDING WHEELS

At first series of testing the blade holding wheels were produced by using flat iron bars.

There was alignment problems and have not precious circular shape. At this stage motor bike

and bicycle rims were used as blade holding wheels. These are available in local market and

can be getting more accuracy. It welded supporting arms to bear hub.

Figure 7.2: Blade Holding Wheels

7.3 MANUFACTURING OF BEARING HOLDER

This component was designed for attach bearing to the floating structure. This bearing holder

consists of two L irons which bolted as L shape. Lengthy L iron bolted vertically to the

floating‟s platform. Other L iron bolted to the lengthy L by bolts and it can be adjusted

vertical direction upwards or downwards.

Figure 7.3: Bearing Holder



7.4 MANUFACTURING OF FLOATING STRUCTURE

Floating structure is made out of from waste barrels. It used four barrels and fixed two barrels

in longitudinal direction and fabricate platform along it. Each platform bolted in to the

bearing holders. Both floaters fixed to the water wheel symmetrically.

Figure 7.4: Floating Structure

Figure 7.5: Assembled floating type water wheel



8. PERFORMANCE TESTING OF NEWLY DESIGNED MODELS

Manufacturing of the second series test models, it was decided to check it in the water flow

channel with control conditions. It was chose most appropriate site in Kuruvita, Parakaduwa

area. As first test series, it performed based on “Brake Load Test” for each models to obtain

relationships between parameters. It is assumed that assumptions in the first series can use for

this step series of test.

DATA:

Average flow velocity of water flow in the channel = 0.6 ms-1

Diameter of pulley = 18 cm

Real situation drowning ratio = 70 %

8.1 PERFORMANCE TESTING OF MODEL 1

OBSERVATIONS:

Table No.8.1: Observation Values for Model 1

Tight Side Tension

(T1) / (Kg)

Slack Side

Tension (T2) /

(Kg)

RPM

1.38 0.48 17.43

2.36 0.97 16.99

3.16 1.45 16.35

4.16 1.94 15.45

5.18 2.42 14.13

6.38 3.4 12.99

9.88 4 10.42

11.06 5.02 9.17

13.01 6.08 8.49

13.94 6.86 7.89

14.82 7.52 7.5



RESULTS:

Table No.8.2: RPM Vs Power for Model 1

RPM Power (W)

17.43 1.450374

16.99 2.183475

16.35 2.584961

15.45 3.171185

14.13 3.605715

12.99 3.579032

10.42 5.664808

9.17 5.120901

8.49 5.439777

7.89 5.164763

7.5 5.062025



Gra

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8.1



Table No.8.3: RPM Vs Efficiency for Model 1

RPM Efficiency (%)

17.61 5.19272

16.42 5.778947

15.73 6.733101

15.24 6.233433

14.12 5.976798

15.1 7.253409

12.99 6.023621

12.83 5.09515

12.17 5.12245

11.02 6.001101

9.4 5.00714

7.29 3.744511



Gra

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8.2




OBSERVATIONS:


Tight Side Tension (T1) /

(Kg)

Slack Side Tension

(T2) / (Kg)

RPM

0.08 0 20.14

4.6 1.58 18.03

6.44 2.18 17.93

7.28 2.96 17.61

9.28 3.92 16.77

11.37 4.91 16.15

12.5 5.87 15.87

14.4 6.93 15.33

14.68 7.49 15.32

15.98 8.51 15.15

18.64 10.35 14.84

23.8 13.01 14.65



RESULTS:


RPM Power (W)

20.14 0.148967

18.03 5.034343

17.93 7.062038

17.61 7.03369

16.77 8.310707

16.15 9.645954

15.87 9.728157

15.33 10.58773

15.32 10.18422

15.15 10.46341

14.84 11.3744

14.65 14.61501



Gra

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8.3




RPM Efficiency (%)

20.14 0.25543

18.03 8.632275

17.93 12.10912

17.61 12.06051

16.77 14.25018

16.15 16.5397

15.87 16.68065

15.33 18.15455

15.32 17.46266

15.15 17.94138

14.84 19.50343

14.65 25.06004



Gra

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8.4




OBSERVATIONS:



(Kg)

Slack Side Tension

(T2) / (Kg)

RPM

0.08 0 26.72

1.02 0.48 24.77

1.48 0.98 24.12

2.16 1.47 23.78

3.54 1.95 23.25

5.64 2.43 22.34

8.64 2.91 22.15

14.38 4.49 20.38

15.84 5.51 19.16

17.74 6.57 18.9

18.9 7.35 17.84

19.92 7.91 17.55

22.65 9.75 16.69



RESULTS:


RPM Power (W)

26.72 0.197636

24.77 1.236687

24.12 1.115032

23.78 1.517054

23.25 3.417907

22.34 6.630226

22.15 11.73461

20.38 18.63548

19.16 18.29936

18.9 19.51889

17.84 19.05096

17.55 19.48769

16.69 19.9061



Gra

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8.5




RPM Efficiency (%)

26.72 0.508324

24.77 3.18078

24.12 2.867881

23.78 3.901888

23.25 8.790913

22.34 17.05305

22.15 30.1816

20.38 47.93076

19.16 47.06626

18.9 50.20291

17.84 48.99939

17.55 50.12265

16.69 51.19882



Gra

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8.6




OBSERVATIONS:



(Kg)

Slack Side Tension (T2) /

(Kg)

RPM

0.24 0 22.34

3.5 1.58 20.06

5.58 2.64 19.33

6.58 3.42 18.17

8.06 4.08 18

9.68 5.06 17.34

11.58 6.03 16.4

13.08 6.99 16.13

14.68 8.01 15.73

15.08 8.57 14.15

18.28 10.41 16.22

22.5 13.07 14.81

21.72 13.31 16.12

22.5 15.15 15.16

23.5 16.11 14.74

24 16.67 14.44



RESULTS:


RPM Power (W)

22.34 0.495718

20.06 3.561003

19.33 5.254354

18.17 5.308626

18 6.623625

17.34 7.40681

16.4 8.415443

16.13 9.082215

15.73 9.700513

14.15 8.516822

16.22 11.80227

14.81 12.9124

16.12 12.53433

15.16 10.30212

14.74 10.07122

14.44 9.786137



Gra

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8.7




RPM Efficiency (%)

22.34 1.274994

20.06 9.158957

19.33 13.51428

18.17 13.65387

18 17.03607

17.34 19.05044

16.4 21.64466

16.13 23.35961

15.73 24.94988

14.15 21.90541

16.22 30.35564

14.81 33.2109

16.12 32.23851

15.16 26.49723

14.74 25.90334

14.44 25.17011



Gra

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8.8




OBSERVATIONS:


Tight Side

Tension (T1) /

(Kg)

Slack Side Tension

(T2) / (Kg)

RPM

0.08 0 10.96

3.36 1.58 7.56

5.12 2.24 5.83

5.89 2.8 3.95

6.58 3.3 4.91

7.28 3.78 4.69

8.18 4.26 3.94

8.98 4.74 4.13

9.45 4.79 3.92

10.5 5.57 3.81



RESULTS:


RPM Power (W)

10.96 0.081066

7.56 1.244176

5.83 1.552391

3.95 1.128485

4.91 1.489003

4.69 1.517683

3.94 1.427981

4.13 1.619034

3.92 1.688932

3.81 1.736649



Gra

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8.9




RPM Efficiency (%)

10.96 0.139003

7.56 2.133361

5.83 2.661851

3.95 1.934988

4.91 2.55316

4.69 2.602337

3.94 2.448527

4.13 2.776122

3.92 2.895974

3.81 2.977793



Gra

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8.1

0



8.6 DISCUSSION ON RESULTS

8.6.1 THE COMPARISON BETWEEN THEORETICAL AND PRACTICAL VALUES

OF OUTPUT POWER FOR EACH MODEL

Experimental power and rotational speed were taken from optimum point of power Vs RPM

graphs.

Table No.8.16: Theoretical and practical values of output power for each model

Model Theoretical power output

( W)

Experimental Power Output

(W)

M -1 13.94 5.265

M -2 44.05 21.12

M- 3 30.63 21.74

M -4 4.91 11.64

M- 5 7.37 1.541

Possible reasons for the deviation between theoretical and experimental values:

Due to the unavoidable circumstances it was difficult to keep the flow rate

constantly. The theoretical power outputs were calculated were based on constant

flow velocity of 0.6ms-1

and drowning ratio 90%. In experimental condition flow

velocity varied between 0.6ms-1

to 1ms-1

, drowning ratios varied between 50% to

100%.

The alignment of shaft and bearing was not accurate the functioning of bearing

was not proper. Nut and Bolt used for attach parts in the water wheel. There was a

probability to loosen nut and bolts. It may be reduced force in water where it used

to developed torque in the water wheel



8.6.2 EFFECT ON CHANGE IN PARAMETERS OF WATER WHEEL

Analysis was based on change in one parameter at the time with other parameters are

constant. Experimental power and rotational speed were taken from optimum point of power

Vs RPM graphs.

CHANGING WIDTH OF BLADES

Table No.8.17: Experimental Values for M -4 and M-5 (Width)

Model Width of blade(cm) Experimental output

power(W)

Experimental

rotational speed

(RPM)

M-4 40 11.64 11.88`

M-5 60 1.541 4.766

M-4 has higher power than M-5.Rotational speeds are change with considerable deviation.

According to the experimental result reducing width of blade caused to increasing of power.

CHANGING TYPE OF CURVE

Table No.8.18: Experimental Values for M -1 and M-3 (Curve)

Model Type of curve Experimental output

power(W)

Experimental

rotational speed

(RPM)

M-1 C-1 5.265 7.806

M-3 C-2 21.74 8.241



Shape of blade curves‟ is critical parameter of the water wheel in sense of output power. C-2

has higher effective depth and effective area than C-1. C-1 has shape of cylindrical parts

shape. C-2 has curve shape with large curvature at side on the immersion of the blade.M-3 is

better than M-1 and M-3 is most appropriate for implementation of floating type water wheel

for Pico hydro system.

CHANGING DIAMETERS OF WATER WHEEL

Table No.8.19: Experimental Values for M -2 and M-5 (Diameter)

Model Diameter(cm) Experimental output

power(W)

Experimental rotational

speed (RPM)

M-2 88.5 21.12 4.351

M-5 72 1.541 4.766

According to the experimental output power M-2 has higher power than M-5. Rotational

speed differs in slightly. It proves theoretical analysis with limited range. It concludes that

increasing of power when diameter increased.

CHANGING DROWNING DEPTH OF BLADES

Table No.8.20: Experimental Values for M -1 and M-4 (Depth)

Model Effective depth of

blade (cm)

Experimental output

power(W)

Experimental

rotational speed (RPM)

M-1 14 5.265 7.806

M-4 11 11.64 11.88

It was shown in experimentally reducing effective depth of blade caused to increase of output

power. Theoretically proves reducing of depth caused to decrease of power. It conflict to use

theoretical analysis for that situation.



9. DEVELOPMENT OF END PRODUCT

9.1 DEVELOPMENT OF WATER WHEEL

Water wheel is driven by impact break power of flow of water. Experiments showed that it

can increase impact break power of water increases the output power water wheel. It is

suitable to cover the left and right side edges of the blade. Fixture method of blade from nut

and bolt was not suitable for running longer period. It is suitable to fix blades by welding

method.

Figure 9.1: Edge covered curve blade

9.2 DEVELOPMENT OF STRUCTURE

Designed Floating structure was not determinate structure .It was transform to the rigid

structure by fixing support bars.

Designed floating barrels are bluff bodies. To reduce impact on water flow from bluff body it

was fixed cone shape metal sheet parts opposite to flowing direction of water.

Figure 9.2: Supporting structure Figure 9.3: water flow guiding method



9.3 DEVELOPMENT OF POWER TRANSMISSION METHOD

The critical problem of water wheel is slow rotational speed. This is a major problem for find

the electrical power generator for low RPM. There is lowest RPM generator has 700 RPM in

available in the Sri Lankan market.

There was 800 RPM generator used for power generation in the newly designed floating type

water wheel. It was used a belt-pulley system for power transmission. First, large pulley

attached to the shaft and connects to the bicycle rims small pulley through a V belt. Then

bicycle tire touch rigidly generators shaft. This power transmission convert rotation speed

1:50 ratio. This method consumes higher loss over 50% total mechanical powers generated

on the water wheel.

Figure 9.4: Power transmission apparatus

Drive

pulley

Driven

pulley

Generator

shaft drive

rim

Generator



10. IMPLEMENT OF NEWLY DESIGNED FLOATING TYPE WATER

WHEEL

10.1 ELECTRICAL PART OF THE WATER WHEEL

Table No.10.1: The connected power generator specifications

Number of poles 6

Maximum power output 100W

RPM at maximum power out put 800

Frequency of output power 50Hz

The water wheel is rotating about 14 revolutions per minute. It has been coupled with

pulleys and belt systems and it increases the rpm up to 800. After attaching the generator to

the floated water wheel, it was got measurement of electrical power output by using “Fluke”

equipment.

From the Graph No.8.5 for Model 03 (M-3)

Mechanical power at 14 RPM = 19.29 W

Electrical Power output = 9.8 W

Losses during the power transmission and generator losses = 19.29 – 9.8

= 9.49 W

The generator used for M-3 without considering “Optimum power point” due to

unavailability of low RPM generators in the Sri Lankan market.



SUGGESTIONS

It is suitable to use low RPM generator for electrical power generation. 100 RPM

generators are available in the global market. It can use in the floating type water

wheel with a suitable power transmission method.

Pulley drives can use maximum speed increasing of 1:3. When it may needs beyond

that speed, it is suitable to use alternative power transmission method.

Power losses during the power transmission should be minimizing.

It is recommended that end users of water wheel must use efficient power consuming

products such as CFL bulbs, LED integrated bulbs, etc.

Electrical power output of M-3 was 9.8 W due to water channels flow velocity. It is difficult

to get direct electrical power from the water wheel to end users. It is recommended to use

battery bank with electrical control unit. According to the general demand curve for electrical

power, maximum power usage in 6.00 PM to 9.00 PM. Battery bank is charged in 24 hours

continuously. Both water wheels‟ power and battery bank power use in the maximum power

demand time in between 6 PM- 9 PM.

Figure 10.1: Setting at water Figure 10.2: Electrical testing



10.2 EFFECTIVENESS OF THE FLOATING TYPE WATER WHEEL

To check effectiveness of the water wheel for electrical power generation, it is essential to

performed energy audit of end user. The energy audit is based on general values of power

consuming for a rural home in Sri Lanka.

Number of persons live in the home = 4

Number of 7W CFL bulbs = 4

Number of hours bulbs lit = 4 hours

Power consumption of B/W TV = 40 W

Number of hours TV On = 2 hours

Power consumption of radio = 10 W

Number of hours radio On = 4 hours

It is important that 7 W CFL bulb is equal to the 40 W Filament bulb power.

ANALYSIS

Daily power consumption for bulbs = 7x4x4

= 112 Wh

. Daily power consumption for TV = 40x2

= 80 Wh

Daily power consumption for radio = 10x4

= 40 Wh

Total Daily Power consumption = 112+80+40

= 232 Wh

Total electrical power generated from the water wheel = 9.8x24

= 235.2 Wh

Power consumption in demand curves peak hours (6 pm to 9 pm) = 7x2x3 + 40x2

= 122 Wh

Power generation in peak hours = 9.8x3

= 29.4 Wh



Required power units from the battery bank = 122 – 29.4

(Insufficient power in peak hours gets from the battery bank) = 92.6 Wh

Maximum power output from a 12 V battery = 31x12 Wh

= 372 Wh

Additional amount of power (92.6Wh) can be get from a charged 12V- 31AH Battery



11. CONCLUSION AND RECOMMENDATION

Table No.11.1: Comparison between Pico Hydro Vs Other energy sources (May-2009)

Energy Source Initial Cost

(Rs.)

Operating Cost

per month

(Rs.)

Operating

Time(hours per

day)

Life Time

(Years)

Water Wheel 35000(20W

unit) - 24 10

Solar Power 85000(100W

unit) - 5 12

Wind Power 150000 200 12 10

Kerosene Oil - 765 4 -

Grid powered

wet battery 80000 900 3 4

While comparing renewable energy sources available for rural areas floating type water

wheel has number of advantages. Due to the 24 hours continuous operating time 20W water

wheel will be equal for 100W solar panel with high initial cost. Water wheel is low cost in

initially when compare with wind power. Operating cost has become also minimum when

compare with non renewable energy sources. It has been proved the water wheel has been

made by using raw materials which available in the local market. That saves the foreign

currency in Sri Lanka.



Table No.11.2: Implement floating type water wheel model

Model Name (Final Product) RUFW-12-20x40

Water flow 16.6 l/s

Blades 20x40 curve type, 12blades

Diameter 0.72 cm

RPM 10

Mechanical Power Out put 20W

The developed floating type water wheel is suitable with given conditions in the Table

No.11.2.

Table No.11.3: Cost analysis for floating type water wheel for Pico Hydro units (RUFW-12-

20x40) (May-2009)

Blades Rs. 3500/=

6 pole generator Rs. 20000/=

Battery bank Rs. 8000/=

Fabrication and raw materials Rs. 4500/=

Total Rs. 35000/=

Floating type water wheel has very low rotational speed due to no head. It has

higher torque comparing other Pico hydro systems. It is recommended that this

type of water wheel can use torque applications such as water pumping

applications. It is used in Pico hydro systems, recommended that use low RPM

electrical power generator. (Available in 100 RPM) It must be used with high

efficiency power transmission method rather than belt drive systems.



Electrical power generator used in water wheel should be well covered for water

proofing.

Appropriate Battery bank must use to store power. Water wheel has low power

output. It is difficult to get direct current from the generator and suitable method is

storing (charging) it in a battery bank.

The water wheel recommended to using in laminar flow site with safe to

instantaneous flooding and other natural disasters.

Floating structure should be able to guide the water flow into the water wheel.



12. REFERENCES

[1]. Dumitru cuciureanu, dan scurtu, doru calarasu, eugen-vlad nastase, THEORETICAL

AND EXPERIMENTAL APPROACH OF UNDERSHOT WATER WHEELS, ISSN 1224-

6077, the international conference on hydraulic machinery and equipments, Timisoara,

Romania, 2008, pp121-124

[2]. Walter Eshenaur , Roger E. A. Arndt, Charles Delisio, Paul N. Garay, Christopher D.

Turner, VITA, 1600 Wilson Boulevard, Suite 500, Arlington, Virginia 22209 USA

”UNDERSTANDING HYDROPOWER”

[3]. Gerald Muller, Christian Wolter, The breastshot water wheel: design and model tests,

Institution of Civil Engineers, 2004

[4]. MULLER G. and KAUPPERT K. Performance characteristics of water wheels. IAHR

Journal of Hydraulic Research (paper 2454, in press).

[5]. www.floatingwaterwheel.co.za

[6]. www.engineeringtoolbox.com/dragcoefficient-d_627.html

[7]. www.atkinsopht.com/row/liftdrag.htm

[8]. www.ice.org

[9] www.lmnoeng.com/Weirs/vweir.htm

[10] www.waterflow.info

http://www.floatingwaterwheel.co.za/

http://www.engineeringtoolbox.com/dragcoefficient-d_627.html

http://www.atkinsopht.com/row/liftdrag.htm

http://www.ice.org/

http://www.lmnoeng.com/Weirs/vweir.htm



APPENDICES

A 1

Table No. A 1.1: Flat Plate, Drag And Lift Coefficients.

Incidence angle α

(degree)

Drag coefficient

CR

Lift coefficient

Cp

30 1.17 2.03

35 1.53 2.24

40 1.89 2.23

45 1.17 1.17

50 1.32 1.10

55 1.45 1.02

60 1.58 0.92

65 1.70 0.79

70 1.80 0.66

75 1.88 0.51

80 1.93 0.35

85 1.96 0.18

90 1.98 0.00



1.17

1.53

1.89

1.17

1.32

1.45

1.58

1.71.8

1.88

1.93

1.96

1.98

2.03

2.24

2.23

1.17

1.11.0

20.9

20.7

90.6

6

0.51

0.35

0.18

000.511.522.5

3035

4045

5055

6065

7075

8085

90

Cr Cp

Gra

ph N

o.

A 1

.1

The

Gra

ph o

f D

rag a

nd L

ift

Coef

fici

ents

for

Dif

fere

nt

α



A 2

Figure A 2.1: Cross section of V-Belt

Table No: A 2.1: Dimensions of standard V-belts according to IS: 2494-1974.

Type of belts Power ranges in

kw

Minimum pitch

diameter of the

pulley(D) mm

Top width(b)

mm

Thickness(t)

mm

A 0.7-3.5 75 13 8

B 2.0-15.0 125 17 11

C 7.5-75.0 200 22 14

D 20.0-150.0 355 32 19

E 30.0-350.0 500 38 23



Figure A 2.2: Cross section of V-grooved pulley

Table No: A 2.2: Dimensions of standard V- grooved pulleys according to IS: 2494-1974

Type of

belt w d a c f e

No.of sheave

grooves (n)

Groove angle

(2β) in degrees

A 11 12 3.3 8.7 10 15 6 32,34,38

B 14 15 4.2 10.8 12.5 19 9 32,34,38

C 19 20 5.7 14.3 17 25.5 14 34,36,38

D 27 28 8.1 19.9 24 37 14 34,36,38

E 32 33 9.6 23.4 29 44.5 20 -



MANUFACTURING DRAWINGS



NOTES

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