Savonius Wind Turbine

DON BOSCO TECHNICAL COLLEGE

Mechanical Engineering Department

Mandaluyong City

“Design of a Savoinius Wind turbine that produces 10 KW of Power”

Design Proposal

In partial fulfillment of the requirements in Fluid Machinery

SUBMITTED BY:

El King M. Posadas IV-ME

Sean Tutaan

SUBMITTED TO:

Engr. Ernesto M. Ponce P.M.E. M.B.A

TABLE OF CONTENTSAPPROVAL SHEETCHAPTERS

PAGEAcknowledgement ……………………………………………….. 1Background of the Study……………………………………………….. 2Actual design ………………………………………………….. 5Data of the Design………………………………………………….. 6Data sheet…………………………………………………………….. 6Formulation…………………………………………………. 7Assumption…………………………………………………. 12Design drawn…………………………………………………….. 13Calculation…………………………………………………………. 15Summarization…………………………………………………………... 20Design draw in the field……………………………………………………… 21Recommendation…………………………………………………. 22Conclusion…………………………………………… 22Reference……………………………………………………………….. 23

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Acknowledgement:

First of all I would acknowledge our Professor Engr. Ernesto L. Ponce P.M.E, M.B.A. for helping me to complete and give me ideas for designing this project and thanking him for being a good teacher and a good example for us. He is the one who pushes us to our limit to make impossible things and giving us deeper understanding on our lessons. I would like to thank also my parents for giving me advices and willingly supporting me trough my hard times. I would like to thank also my colleagues for giving comments and advices on my design. Of course I would thank God for giving me inspiration and strength in life even in my worst days and hardships. If it is not for him I cannot do this design.

CHAPTER I

INTRODUCTION

Background of the Study

Power energy is one of the biggest consumption of people whether it comes from nuclear, solar, mechanical, hydro, wind, thermal, sound, kinetic, geothermal and so forth. These entire things are consumed by each one of us.

Likewise, hydro power is something that we need to focus on since it is free and available to anyone. As a result, this explains why generating energy through hydro power has become one of the cheapest methods. Hydro Power also signifies a renewable source of energy. In no way could you ever run out of hydro power. It is capable of generating considerably high amounts of extractable power, which is higher than the quantity used by humans currently from all combined sources available.

There are many ways in which transforming water into energy can be beneficial, as water is used for a variety of purposes and activities.

We shall now explore a range of hydro energy factors, including how water can be fun and how to use this water to your own advantage.

hydro energy has existed since life on our planet began; it is currently used in recreation and industry.

water turbine is a device that converts kinetic energy from the water into mechanical energy. If the mechanical energy is used to produce electricity, the device may be called a water generator or water charger. If the mechanical energy is used to drive machinery, such as for grinding grain or pumping water, the device is called a tidal mill or water pump. Developed for over a millennium, today's wind turbines are manufactured in a range of vertical and horizontal axis types.

water turbines are useful for many people. It is not just environmental friendly and it generates power for us. We just need to know how to use our resources well.

A tide mill is a water mill driven by tidal rise and fall. A dam with a sluice is created across a suitable tidal inlet, or a section of riverestuary is made into a reservoir. As the tide comes in, it enters the mill pond through a one way gate, and this gate closes automatically when

the tide begins to fall. When the tide is low enough, the stored water can be released to turn a water wheel.

Tide mills are usually situated in river estuaries, away from the effects of waves but close enough to the sea to have a reasonable tidal range. These mills have existed since the Middle Ages, and some may go back to the Roman period.

A modern version of a tide mill is the electricity generating tidal barrage.

Newer types of tidal power often propose a dam across a large river estuary. Although it represents a source of renewable energy, each proposal tends to come under local opposition because of its likely impact on coastal habitats. One proposal, which came to fruition in 1966, is the Rance barrage which generates 250MW. Unlike historical tide mills which could only operate on an ebb tide, the Rance barrage can generate electricity on both flows of the tide or it can be used for pumped storage depending on demand. A less intrusive design is for a 1MW free standing turbine, constructed in 2007 at Strangford Lough Narrows - also close to an old tide mill.

The Darrieus turbine is popular for tidal current power generation in Japan. It is simple in structure with straight wings rotating around a vertical axis, so that it has no directionality against the motion of tidal flow which changes its direction twice a day. However, there is one defect in the Darrieus turbine; its small starting torque. Once it stops, a Darrieus turbine is hard to re-start until a fairly fast current is exerted on it. To improve the starting torque of the Darrieus turbine used for tidal power generation, a hybrid turbine, composed of a Darrieus turbine and a savonius rotor is proposed. Hydrodynamic characteristics of a semi-circular section used for the Savonius bucket were measured in a wind tunnel. The torque of a two bucket Savonius rotor was measured in a circulating water channel, where four different configurations of the bucket were compared. A combined Darrieus and Savonius Turbine was tested in the circulating water channel, where the effect of the attaching angle between Darrieus wing and Savonius rotor was studied. Finally, power generation experiments using a 48 pole electric generator were conducted in a towing tank and the power coefficients were compared with the results of experiments obtained in the circulating water channel.

Actual design:

Parameters that should be considered upon the application of the Savonius wind turbine.

1. The location – this is essential to the design this factor will affect the design. The

wind velocity of the location is needed for the efficiency of the turbine. The Savonius

wind turbine needs a lot of space and has a good wind velocity for maximum

efficiency.

2. The size of the design – the size of the design is important because of the power

needed in this case I need to produce 10KW of turbine power so the area of the

design will be in a big scale design.

3. Weather conditions - the design should also consider the atmospheric conditions.

The design is in a big scale so the design should withstand all the weather

conditions.

4. Cost of materials used in the design – the cost is essential to the design. The

design should be less cheap but efficient for the investors that will raise the funds

for the project.

DATA OF THE DESIGN

I have been asked to design a Savonius wind turbine that will produce 10,000 Watts

of turbine power. It has a maximum height of 40 meters.

DATA SHEET

1. Given output of 10,000 Watts or 10KW.

2. Wind velocity of 4m/s

3. Standard height of 40 meters

Given in the data sheet above, I must consider the following

1.1 Base on my research, a windmill can attain those figures, a much more efficient 3

bladed is the most prefer modern design of windmill nowadays; it can produce a

much more efficient energy. But in my condition which I will create a savonius

wind turbine, a drag type wind turbine, first I must consider the scale of my wind

turbine.

1.2 The wind turbine can produce 10,000 Watts using the air velocity of 4m/s. The

wind turbine should comply to the standard velocity of air.

1.3 Standard height of 40 meters to the ground level. It is the minimum height that

should be followed because of the wind velocity above is greater than the air

velocity in lower grounds.

Needed Information to complete the design and formulations:

In the data of the design I enumerate those parameters that are being given to possibly make my design but now I will extent it further for the data needed or information need for me to complete my design.

1. First I need to know the concepts and equations and principles used to compute for my wind turbine.

2. First we must analyze the forces hitting the blades by analyzing drag forces of wind to the blades.

FD=CDAp (Vρ o2/2)

Where; FD= Drag forceCD=Coefficient of dragAp=Projected area

= Density of airρVo= Initial velocity of the wind

In this table we can determine the coefficient of drag where the wind passes on different kinds of shapes of blades.

3. The tip speed ratio along with the coefficient of the rotor

As you can see in the chart, the Savonius windmill has the maximum coefficient of .15 and tip speed ratio of .8, well this chart is being derived as an empirical, which is the cause of experience of those experts dealing with turbine.

4. Computing for the Tangential velocity

TSR= VB/Vw

Where; TSR= TIP SPEED RATIOVB = Tangential velocityVw=Velocity of the wind

5. Computing for the revolution per minute

N = (Vb/2 r) 60π

Where;

Vb = Tangential forcer = radius of the blade to the shaft

6. Computing for angular velocity

Giving the equation

= 2 N/60 ω π

Where;

= ω angular velocity

N= revolution per minute

7. Computing for the torque

FD1(r)-FD2(r) = T

Where;

FD1 = Drag force on the Semicircular section 1FD2 = Drag force on the Semicircular section 2r = radius from the center of the turbine to the tip of blades

8. Computing the Power of the turbine

PT = T ω

Where;

PT = Power of the turbine

T = Torque

= angular velocityω

9. Computing for the Power of the Wind

Pw=1/2 AVρ 13

Where;

Pw = Power of the wind

= Density of the airρ

V1 = Initial velocity of the wind

AT = Area total of the blades

10. Computing for the shaft diameter and selecting of material

D = (32(N)/ )(√3/4(T/Sπ y)2)1/3

Where;

N = Design factor

T = Torque

Sy = Yield point

=

First, we must determine the properties of steel shaft.

From figure A4-2,

Now we get the

1. Sy2. Percent Elongation more than 5% is ductile enough

Other relevant assumptions w/ complete design justification:

1. Diameter of the blades

The diameter of the blades is essential to the design. I analyze it well and realize that the diameter and size of the blade is directly proportional to the power output. The material that will be use for the blade is Fiber reinforced plastic. The thickness of the blade is .5 inch.

2. Diameter of the shaft

The diameter of the shaft is analyzed and base from my understanding reading and researching that the shaft need to be ductile because of fluctuating loads or dynamic loads.

3. Generator

The generator will be a permanent generator magnet for vertical turbines. The generator will be connected along with a gear box to the bottom of the shaft of the turbine. The generator that will be use is a 3kw generator. So I will be making 4 savonius wind turbine so I can reach the 10kw requirement.

DESIGN DRAWN

1. The diameter of the blades. Each blade is a semi circular.

Forces acting upon the blades

2. The total height of the turbine and the total height of the blades. Representation of shaft and the bearing. The generator will be connected using a sprocket above 1 meter the below bearing.

3. Three Dimensional drawing of the Savonius wind turbine

CALCULATION AND SUMMARIZATION

1. GIVEN: V = 4m/sA= (20m)(8)= 160m2

= 1.23 kg/mρ 3

TSR= .8

2. Computing for the Drag force

FD=CDAp (Vρ o2/2)

Where; CD is analyzed on the table of types of drag force on the bladeFD1= 2.3(4x20)(1.23)(8)FD1= 1810.56 N

FD2= 1.2(4x20)(1.23)(8)FD2= 944.92 N

FD total = FD1 - FD2

FD total = 865.92 N

3. Computing for the Torque

Using summation of Moment at the center of the Blades

FD1(r)-FD2(r) = T

1810.56(3.50) - 944.92(3.50) = T

T = 3030.72 N-m4. Computing for the tangential velocity

TSR= VB/Vw

.8= VB/4VB = 3.2 m/s

5. Computing for the revolution of the blades per minute

N = (Vb/2 r) 60πN = (3.2/2 (3.5))(60)πN = 8.73 rpm

6. Computing for the Power of the Turbine

PT = T ω

Where;

= 2 N/60 ω π

PT= T(2 N/60)π

PT= 3030.72(2 (8.73)/60)π

PT= 2770.69 Watts

7. Computing for the Power of the Wind

Pw=1/2 AVρ 13

Pw= ½((1.23)(20x8)(4)3

Pw=6297.6 Watts

8. Computing for the Shaft diameter

D = (32(N)/ )(√3/4(T/Sπ y)2)1/3

Where;

From table A4-2, We use AISI 1144 900F

N = 2.5 for the design factor

Sy=86,000

D= (32(2.5)/ )(√3/4(26824.09/86000)π 2)1/3

D= .418 m

9. For the bearing for the shaft we will choose from the table below

In our computation of the shaft is 418mm so we will use the 400mm diameter of bearing in the shaft available in the table.

10. The generator will be use is a vertical permanent Generator that can store 3kw

The gear ratio will be 1:6 in order to comply to the rpm needed in the specification of the generator.

SUMMARIZATION

1. Total Drag force = FD total = 865.92 N

2. Torque = T = 3030.72 N-m3. Tangential velocity = VB = 3.2 m/s4. Revolution = N = 8.73 rpm5. Power of the Turbine = PT= 2770.69 Watts6. Power of the wind = Pw=6297.6 Watts

7. Shaft Diameter =D = .418 m

8. Area of the blades = 160m2

9. Total drag force = FD total = 865.92 N10. Yield point of the shaft = Sy=86,000

11. Generator = 3Kw,55 rpm,175kg12. Shaft material = AISI 1144 900F13. Material for the blade = Fiber reinforced plastic14. Height of the blades = 20 m

15. Diameter of the Blade = 7 m

16. Thickness of the blade is = .5 in

DESIGN DRAW ON THE FIELD

Each turbine produces 2770.69 x 4 =11,082.76 Watts

RECOMMENDATION

From the results and researching about this turbine I may recommend that this kind of turbine needs a place that has a wind velocity of 4m/s or higher. This turbine is a drag type so it needs a high wind velocity. To maximize the power output we may need to make a large savonius turbine. We may increase the height or enlarge the diameter. I may recommend that the materials that will be used needs to be strong because it is a drag type it catches power of wind to rotate.

CONCLUSION

In my experience designing the turbine, I have concluded that the savonius turbine needs a lot of space because it needs to be a large one to produce a greater power. I have concluded that the blades are semi circular with different drag coefficient in each side. The savonius turbine is a high torque it means that it can rotate easily the gears. The generator is a permanent. The turbine needs two bearings. The savonius blade velocity is slower than the wind. I have concluded that it needs a strong supports so it may not cause danger.

GLOSSARY

1. Drag Force -  refers to forces which act on a solid object in the direction of the relative fluid flow velocity

2. Torque - is the tendency of a force to rotate an object about an axis,3. Tangential velocity - When the rigid object rotates around in a circle, the linear

velocity at a point r meters away from the center of the circle (with the vector being tangent to the circle) is the tangential velocity.

4.  Turbine - is a rotary engine that extracts energy from a fluid flow and converts it into useful work.

5. Generator - an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge (usually carried by electrons) to flow through an external electrical circuit.

6. Semi-circle -   is a two-dimensional geometric shape that forms half of a circle.7. Diameter - a diameter of a circle is any straight line segment that passes through the

center of the circle and whose endpoints are on the circle.8. Elongation -  is the transformation of a body from a reference configuration to

a current configuration9. Density - material is defined as its mass per unit volume.10. Wind energy- is one of the most cost effective of all types of renewable energy. It

does not create pollution or waste and the fuel, wind, is not used faster than it is produced.

11. Efficient - wind turbines, which convert the mechanical energy of the wind into usable electrical energy, requires extensive use of physics

12. VAWT -  are a type of wind turbine where the main rotor shaft is set vertically and the main components are located at the base of the turbine\

13. Angular velocity -is defined as the rate of change of angular displacement and is a vector quantity (more precisely, a pseudovector) which specifies the angular speed of an object and the axis about which the object is rotating.

14. Tip Speed ratio - for wind turbines is the ratio between the rotational speed of the tip of a blade and the actual velocity of the wind.

15. Coefficient of Drag - is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment such as air or water.

16. Gear - is a rotating machine part having cut teeth, or cogs, which mesh with another toothed part in order to transmit torque.

17. Bearing - is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement.

References:

1. Crowe, Elger, Robertson. Engineering Fluidmechanics. Wiley eight Edition

2. S. L. Dixon and C.A. Hall, Fluid Mechanics and Thermodynamics of Turbomachinery,

Sixth Edition.

3. Mott Robert L. Machine Elements Design “A Practical Approach”, LPE Fourth Edition