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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
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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.
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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
8.2 PERFORMANCE TESTING OF MODEL 2 ............................................................. 74
8.3 PERFORMANCE TESTING OF MODEL 3 ............................................................. 79
8.4 PERFORMANCE TESTING OF MODEL 4 ............................................................. 84
8.5 PERFORMANCE TESTING OF MODEL 5 ............................................................. 89
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
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12. REFERENCES............................................................................................................ 106
APPENDICES .................................................................................................................. 107
A 1 ................................................................................................................................ 107
A 2 ................................................................................................................................ 109
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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
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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.8.4: Observation Values for Model 2 ................................................................... 74
Table No.8.5: RPM Vs Power for Model 2 .......................................................................... 75
Table No.8.6: RPM Vs Efficiency for Model 2 .................................................................... 77
Table No.8.7: Observation Values for Model 3 ................................................................... 79
Table No.8.8: RPM Vs Power for Model 3 .......................................................................... 80
Table No.8.9: RPM Vs Efficiency for Model 3 .................................................................... 82
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
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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
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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.8.7: Power Vs RPM for the model 04(M-4) ......................................................... 86
Graph No.8.8: Efficincy Vs RPM for the model 04(M-4) ................................................... 88
Graph No.8.9: Power Vs RPM for the model 05(M-5) ......................................................... 91
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
Project Report Development of Floating Type Water Wheel For Pico Hydro System
Department of Mechanical & Manufacturing Engineering 2
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,
Project Report Development of Floating Type Water Wheel For Pico Hydro System
Department of Mechanical & Manufacturing Engineering 3
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.
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Department of Mechanical & Manufacturing Engineering 4
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.
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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.
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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.
Project Report Development of Floating Type Water Wheel For Pico Hydro System
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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
Project Report Development of Floating Type Water Wheel For Pico Hydro System
Department of Mechanical & Manufacturing Engineering 8
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
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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.
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The project will follow experimental basis development because the theoretical developments
have been not matched perfectly in previous cases.
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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
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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
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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)
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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
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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)
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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
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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)
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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
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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
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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
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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)
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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
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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.
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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.
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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
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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
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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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4.2 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
Flow Speed of water = 0.62 ms-1
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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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4.3 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
Flow Speed of water = 0.58 ms-1
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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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4.4 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
Flow Speed of water = 0.605 ms-1
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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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4.5 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
Flow Speed of water = 0.54 ms-1
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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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4.6 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.
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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.
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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
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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.
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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
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Curve Model 2 (C-2)
Width of blade = 40 cm
Length of blade = 20 cm
Mathematical equation of curve => Y= -59.059X2+35.35.6X-52534
Curve Model 3 (C-3)
Width of blade = 40 cm
Length of blade = 28 cm
Mathematical equation of curve => Y= -13.069X2+782.64X-11693
Curve Model 4 (C-4)
Width of blade = 60 cm
Length of blade = 28 cm
Mathematical equation of curve => Y= -13.069X2+782.64X-11693
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.
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According to chapter 3, from Eq.3.1 to Eq.3.13
Model-1 specification:
Blade = C-1
Blade width (L) = 40 cm
Length of blade = 20 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
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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
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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
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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
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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 %
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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
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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.
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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.
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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
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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.
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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
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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
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Considering Bending Moment at Distance x;
M = R2*x
If distance x is 500mm
M = 134.641 * 0.5
= 67.3205 Nm
If distance x is 600mm
M = (134.641*0.6)-(333.54*0.1)
= 47.4306 Nm
If distance x is 1000mm
M = (134.641*1)-(333.54*0.5)-(45.126*0.4)
= -50.1794 Nm
If distance x is 1200mm
M = (134.641*1.2)-(333.54*0.7)-(45.126*0.6)
+ (494.92*0.2)
= -0.0004 Nm
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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
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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
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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
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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.
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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
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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
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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
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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
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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
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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
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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
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Gra
ph N
o.
8.1
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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
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Gra
ph N
o.
8.2
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8.2 PERFORMANCE TESTING OF MODEL 2
OBSERVATIONS:
Table No.8.4: Observation Values for Model 2
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
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RESULTS:
Table No.8.5: RPM Vs Power for Model 2
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
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Table No.8.6: RPM Vs Efficiency for Model 2
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
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8.3 PERFORMANCE TESTING OF MODEL 3
OBSERVATIONS:
Table No.8.7: Observation Values for Model 3
Tight Side Tension (T1) /
(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
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RESULTS:
Table No.8.8: RPM Vs Power for Model 3
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
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Table No.8.9: RPM Vs Efficiency for Model 3
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
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8.4 PERFORMANCE TESTING OF MODEL 4
OBSERVATIONS:
Table No.8.10: Observation Values for Model 4
Tight Side Tension (T1) /
(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
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RESULTS:
Table No.8.11: RPM Vs Power for Model 4
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
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Table No.8.12: RPM Vs Efficiency for Model 4
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
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8.5 PERFORMANCE TESTING OF MODEL 5
OBSERVATIONS:
Table No.8.13: Observation Values for Model 5
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
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RESULTS:
Table No.8.14: RPM Vs Power for Model 5
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
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Table No.8.15: RPM Vs Efficiency for Model 5
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
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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
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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
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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.
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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
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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
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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.
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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
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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
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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
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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.
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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.
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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.
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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
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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
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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
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A 1
.1
The
Gra
ph o
f D
rag a
nd L
ift
Coef
fici
ents
for
Dif
fere
nt
α
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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
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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 -
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MANUFACTURING DRAWINGS
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NOTES