Vertical Wind Turbine Thesis

VERTI CAL AXI S WIND TURB TURBII NE GROUP GROUP PROJ ECT REPORT Centre Names: M ech cha anical and Ma M anufac nufactur turiing E ng ngiineering & A uto utom mob obiile an and d Ai A ircr cra aft design Engineering Course Names: M.Sc (Engg) in Machine Design & Rotating Machinery Design

Project Team RMD Mr.Chandramouli H.R. Mr.Mohan patnaik Mr.Lokesh kumar. TII T L E PA T

GE

MD Mr.Abinandan Patil Mr.Raghavendra. Mr.Srinath.S. Mr.Srinath.B.V. Mr.Lavakumar Mr.Narendra

FUL L T I M E 2 20 010 BATCH BAT CH

M.S.Ramaiah School of Advanced Studies th

#470-P Peenya Industrial Area, 4 Phase, Bengaluru-560 058 Tel; 080 4906 5555, website: www.msrsas.org

) P M E P ( E M M A R G O R P

M.S Ramaiah School of Advanced Studies –Postgraduate Engineering and Management Programme

M.S.RAMAIAH SCHOOL OF ADVANCED STUDIES

Certificate

HOD, A&AD Department MSRSAS – Bangalore

A & AD & Department MSRSAS – Bangalore

Director MSRSAS – Bangalore

Vertical Axis Wind Turbine

ii


DE CL A RA T I ON ‘Vertical wind turbine’ The Group project Dissertation is submitted in partial fulfilment of academic requirements for M.Sc (Engg) Degree of Coventry University in Rotating Machinery Design (RMD) and Machinery design (MD). This dissertation is a result of investigation of the project team. All sections of the text and results, which has been obtained from other sources, are fully referenced. We understand that cheating and plagiarism constitute a breach of University regulations and will be dealt with accordingly.

Group 1: Rotating Machinery Design Sl. No

Name of the Student

Reg Number

1

H.R.Chandramouli

BSB09010001

2

Mohan patnaik

BSB0910003

3

Lokesh kumar

BSB0910002

Group 2: Machinery Design Sl. No

Name of the Student

Reg Number

1

Abhinandan Patil

BSB09010001

2

Raghavendra

BSB0910006

3

K.Srinath

BAB0910003

4

P.V. Srinath

BAB0910004

5

Narendra

BAB0910005

6

Lavakumar

BAB0910002

Date: 30-05-2011


iii


A CK NOWL EDGE M E N T We would like to express our sincere thanks to our academic guide Dr. S.

Narahari,. Head of the Department, Automotive & Aircraft engineering for his relentless patience and guidance throughout every phase of the project. We would like to acknowledge Dr. Deshpande, faculty of Automotive & Aircraft engineering Department for his valuable guidance throughout the project and as well the procurement of parts for the project. Their support for exploring, identifying the subject matter and technical assistance during problem solving have helped in the successful completion of this project Our sincere gratitude to Dr. S. Narahari, Course manager, Rotating machinery design, and Dr. N.S.Mahesh, Head of the Department of Mechanical & manufacturing Engineering and Course manager, Machine Design, MSRSAS, for giving an opportunity to work on this project. He gave us all the useful information and solutions to overcome the problems we faced. His guidance has been of immense help throughout the project. We would like to thank the Director of MSRSAS, Dr. S.R. Shankapal for providing us with all the required facilities and supporting us in the project undertaken. We would like to thank Prof. Q.H. Nagpurwallah and Dr.M.D.Deshpande for their useful inputs which helped us tremendously. We are also thankful to the staff of MSRSAS for their help during the course of the project.


iv


A BS T RA C T Vertical Axis Wind Turbines are machines that convert the wind energy into mechanical energy, which can be diverted to generate electricity. This project is to develop an aerodynamic simulation model that can be used to understand the dynamics and structural mechanics of the whole system as well as generating electricity. In this regard, a turbine consists of important components of which the generator is one of them.

In this team work, we have designed the Vertical axis wind turbine which is solely based on Savonius type with appropriate blade profile. The design of the blade is based on the basis of conceptual design which is aerodynamically drag-type devices, consisting of two blades acts as vanes and partly like an airfoil when they are edge-on into the wind, creating a small lift effect and thus enhancing efficiency.The blades are fixed and mounted to the main shaft with the help of bushings and fabricated to the frame. Frame is welded to the hub which supports all the main rotating components. Hub also houses bearings at the bottom and another at the top of the main shaft. Rim is fixed to the outer shaft with the bearing for smooth rotation. The rim is connected to a pulley with bearing fitted on the pulley shaft, which in turn rotate dynamo for generating the electricity. This concept is geometrically modelled in CATIA.

Working model of Vertical wind turbine been tested for functionality with different wind speeds. In order to increase the torque of the turbine with respect to the wind speed, a smaller pulley is provided with a bearing support and also it is connected to the dynamo which is directly mounted onto the shaft on the pulley. This type of Vertical axis turbine is more suitable for house hold or domestic generation of electricity.


v


LIST OF CO NTE NTS TI TL E PAGE .....................................................................................................................i DECLARATION.............................................................................................................. ii DECLARATION............................................................................................................. iii ACK NOWL EDGE MENT ...............................................................................................iv ABSTRACT .......................................................................................................................v L IST OF CONT ENTS.....................................................................................................vi L IST OF FIGURES....................................................................................................... vii L ist of tables.......................................................................................................................1 Chapter 1...........................................................................................................................2 1.

Introduction...................................................................................................................2 [1]

1.2 SAVONIUS TURBIBNE .............................................................................2 [1] 1.2.1 Description of the Savonius Rotors .........................................................................3 1.2.2 Blade Design & Manufacturing outline

[4]

...................................................................4

1.2.3 Basic Blade Designs ....................................................................................................4 1.2.4 Blade Nomenclature ....................................................................................................5 1.2.5 Blade Specifications

[1]

................................................................................................5

1.2.6 Blade Material & Manufacturing.................................................................................6 1.2.7 Blade Profile processing ..............................................................................................6 1.2.8 Blade mounting on the shaft ........................................................................................7 1.3. Vertical Axis Wind Turbine Assembly .........................................................................7 1.3.1 Orthographic Views .....................................................................................................8 1.3.2 Belt design ...................................................................................................................8 1.3.3 Blade: ..........................................................................................................................9 1.4 Methodologies-Design & Drawing.................................................................................9 1.5 Manufacturing & Fabrication process ..........................................................................14 1.6 Design Errors. ...............................................................................................................17 1.7. Improvement identified................................................................................................17 1.8. Estimated Cost of the project .......................................................................................17

Conclusion .......................................................................................................................18 Future Scope....................................................................................................................19 References........................................................................................................................20


vi


L IST OF FIGURES Fig.1. 1 Savonius wind turbine ...........................................................................................3 Fig.1. 2 Wind flow on the Blade profile .............................................................................3 Fig.1. 3 Basic Blade designs. ..............................................................................................5 Fig.1. 4 Basic Nomenclature...............................................................................................5 Fig.1. 5 Isometric view of blade .........................................................................................6 Fig.1. 6 Blade profiles.........................................................................................................7 Fig.1. 7 Blade mounting positioning on the shaft ...............................................................7 Fig.1. 8 Assembly of Vertical Axis Wind Turbine .............................................................8 Fig.1. 9 Orthographic views of Vertical axis wind turbine.................................................8 Fig.1. 10 Blade profile ........................................................................................................9 Fig.1. 11 Assembly drawings of Lock nut, Bearing & inner shaft ...................................10 Fig.1. 12 Assembly drawing of Hub with the frame.........................................................10 Fig.1. 13 Assembly drawing Hub, lock nut, shaft housing...............................................11 Fig.1. 14 Belt mounting between rim and the pulley........................................................11 Fig.1. 15 Assembly of Hub, Bearing, Rim, lock nut and the pulley with plate support ...12 Fig.1. 16 Blade mounting..................................................................................................12 Fig.1. 17 Hub Assembly ...................................................................................................13 Fig.1. 18 Shaft housing assembly .....................................................................................13 Fig.1. 19 Assembly of bearing with the shaft ...................................................................14 Fig.1. 20 Overall manufacturing drawings .......................................................................14 Fig.1. 21 Blade and Pulley mounting................................................................................17


vii

M.S Ramaiah School of Advanced Studies –Postgraduate Engineering And Management Programme (PEMP)

L ist of tables Table 1. 1 ....................................................................................................................................... 5 Table 1. 2 Parts of VAWT............................................................................................................. 8 Table 1. 3 ..................................................................................................................................... 15 Table 1. 4 ..................................................................................................................................... 16


1


Chapter 1 1. Introduction Vertical Axis Wind turbines are dimensioned for a nominal running point, i.e. for a given wind velocity. In order to obtain higher efficiency, two or three-bladed fast running wind turbines are preferred. Vertical axis wind turbine (VAWT), such as the Savonius rotor, can extract more energy than fast running wind machines. This idea seems to be in contradiction to the general literature in the field: the Savonius rotors have an aerodynamic behaviour where the characteristics of a drag device dominate, which clearly induces a low efficiency. In fact, using the same intercepted front width of wind L and the same value

σ

of the maximal mechanical

stress on the blades, the delivered power of a Savonius rotor is superior to the one of any fastrunning horizontal axis wind turbine. Savonius rotor can theoretically produce energy at low wind velocities because of its high starting torque and a low angular velocity; it can deliver electricity under high wind velocities, when fast running wind turbines must generally be stopped.

1.2 SAVONIUS TURBIBNE

[1]

A Savonius wind turbine is an example of a drag-based design. Invented by the Finnish engineer S. J. Savonius in 1922, it can be made with different types of blades or scoops, e.g., buckets, paddles, sails, or oil drums. Looking down on the rotor from above, a two-scoop machine would look like an “S” shape in cross section. Savonius wind turbines can and are used in generating the electricity in the strongest winds without being damaged, they are very quiet, and they are relatively easy to make. Savonius turbines do not scale well to kW sizes; however they are useful for small scale domestic electricity generation - especially in locations with strong turbulent winds. The smaller the turbine blades (from the axis to the tip of the blade), the faster the rotation and the less torque force developed. This loss in torque then can be recovered if the blades are made “taller” in the vertical dimension. Because the design is simpler than other types of wind turbines, it finds application in low maintenance situations. Design is simplified because no pointing mechanism is required to allow for shifting wind direction, unlike horizontal axis turbines.


2


1.2.1 Description of the Savonius Rotors [1]

Fig.1. 1 Savonius wind turbine [3]

This is the most efficient Savonius design. It not only has the advantage of air being deflected twice like the design above, but also that the vanes act partly like an airfoil when they are edge-on into the wind, creating a small lift effect and thus enhancing efficiency.

Aerodynamical behaviour- Flow characteristics

Fig.1. 2 Wind flow on the Blade profile [2]

When a wind site is chosen to install wind machines in order to produce electricity, it is expected to extract the maximum possible energy from the wind. Wind speed and power are mostly forecasted using linearised models which do not count very well for the topographic effects. In order to interpolate data, measurements at low heights are used. The forecast is therefore of low accuracy. ¾

Aim

•

To model and explore the Vertical Wind Turbine of a Savonius rotor (S-rotor) wind turbine adapted for household/domestic electricity generation

¾

Objectives

•

Evaluate the best blade offset by field testing using a small prototype model.

•

Produce a turbine capable of generating 10% of the household’s electricity.

•

Build a fully functioning 100 Watt household turbine.

•

To show that using the Savonius turbine for household generation is a viable option.


3


¾

Project scope

¾

The wind turbine set up is used to visualize the flow of wind energy which converts wind in to mechanical energy, which can be diverted to generate electricity.

¾

With the help of this set up homeowners generate their own clean power, thereby reducing Carbon Dioxide emissions.

¾

Using this set up, it easy to contain the generator and other electrical parts at the ground level.

1.2.2 Blade Design & Manufacturing outline [4] ¾

Conceptual Design of Rotating Blades

¾

CAD model (using CATIA V5)

¾

Blade material Selection

¾

Manufacturing Process for the Blade

¾

Blade Mounting

•

Rotor Blades The Savonius rotor concept never became popular, until recently, probably because of

its low efficiency. However, it has the following advantages over the other conventional wind turbines: •

Low maintenance cost.

•

Simple and cheap construction;

•

Acceptance of wind from any direction thus eliminating the need for reorientation;

•

High starting torque;

•

Relatively low operating speed (rpm )

•

Factors involved in construction of Savonius Blades.

¾

The size of the end plates, to which are mounted the buckets, should be about 5% larger than the diameter of the rotor.

¾

The central shaft should be mounted to the end plates only, and not through the buckets.

¾

An aspect ratio of about 2 is desirable from the economic point of view.

¾

Use only two buckets, as a higher number reduces the efficiency.

¾

The use of augmentation devices such as concentrators or diffusers or combination of the two result in increased power coefficient

1.2.3 Basic Blade Designs Vertical Axis Wind Turbine

4


Fig.1. 3 Basic Blade designs.[4] ¾

A -It is very strong due to the central shaft, but slightly less efficient than the other two. However, the extra strength allows the rotor to be supported at one end only.

¾

B- This design is also very simple, and can also be made easily from metal drums or pipe sections. The design is slightly more efficient than the one above as some of the air is deflected by the second vane as it exits the first one.

¾

C--This is the most efficient Savonius design. It not only has the advantage of air being deflected twice like the design above, but also that the vanes act partly like an airfoil when they are edge-on into the wind, creating a small lift effect and thus enhancing efficiency. [5]

1.2.4 Blade Nomenclature

Fig.1. 4 Basic Nomenclature [4]

1.2.5 Blade Specifications [1] Table 1. 1

Sl.No. Swept Area (m2) 1

1m x 0.8m

Wind Speed(m/s) 5.5 m/s

Air Density(kg/m3)

Blade height

Blade diameter (2 nos)

1.23

1m

0.8m

¾

Power output (P) = ½ ρAu3 =1.742pAu3/T* = Watts (W)

¾

By considering the ambient conditions.

¾

Power wind = 0.647Au3 W


5


¾

Where A = area of the turbine, u = wind speed in m/s.

¾

At standard conditions, the power in .8m2 of wind with a wind speed of 5.5 m/s is,

0.647 x 1m x 0.8m x (5.5)3 =86.11 Watts 100 W (approximated power available)[3]

Fig.1. 5 Isometric view of blade[5]

1.2.6 Blade Material & Manufacturing •

Material Properties requirements: [1]

¾

Light weight

¾

Corrosion resistant

¾

Good compressive strength

¾

Machinability

•

Blade material- Aluminum sheet

¾

Thickness of the sheet is 2.5 mm chosen to avoid flattering due to wind speed.

¾

Lightweight and tough hardened aluminum sheet has been used for turbine blade.

1.2.7 Blade Profile processing


6


Fig.1. 6 Blade profiles [4]

Thickness of the aluminium sheet is 2.5 mm, is bent in the form of an arc which is based on the conceptual design of the blade profile.

1.2.8 Blade mounting on the shaft

Fig.1. 7 Blade mounting positioning on the shaft

Sufficient gap has been provided between the two blades during the mounting on the shaft in order to increase the drag force by wind speed. Then the blade is fitted on the shaft with the help of bushings.

1.3. Vertical Axis Wind Turbine Assembly


7


Table 1. 2 Parts of VAWT

Fig.1. 8 Assembly of Vertical Axis Wind T urbine

1.3.1 Orthographic Views

Fig.1. 9 Orthographic views of Vertical axis wind turbine

1.3.2 Belt design Vertical Axis Wind Turbine

8


•

Design for the Length of the Belt 

Length of the belt (L):



Length of the flat belt (open) = π/2*(D+d) + (D-d)2/(4*c) + 2*c



Diameter of Rim = 620 mm; diameter of pulley = 100 mm;



Centre to centre distance = 410 mm



∴Length of the belt = 2110 mm



Considering initial tension of 2% ,length of the belt gets

reduced to 2115-

(0.02*2110) = 2068 mm;  

∴Length of the belt = 2068 mm;

Velocity ratio between the Rim & the Pulley 

Without slip:



Diameter of rim= DA ; Diameter of pulley= D B



NB = (DA/DB)* NA = (620/100)*60 = 372 rpm;



NB = 372 rpm;



With 2% slip:

  

NB / NA = (100-s)/100 * (DA/DB); Velocity ratio = NB / NA = NB = 365 rpm;

1.3.3 Blade:

Fig.1. 10 Blade profile

1.4 Methodologies-Design & Drawing Vertical Axis Wind Turbine

9


Step 1. Bearing Cover

Structure design

Bearing Outer Shaft

•

Possibilities for support. • Shaft with one bearing support at the bottom • C frame with a top and bottom support • Shaft with 2 bearing at top and bottom and another hallow shaft rotating over the bearings

Bearing Spacer HUB 75.0 25.0

A 750.0

Lock Nut Inner Shaft

Fig.1. 11 Assembly drawings of L ock nut, Bearing & inner shaft

Step 2.

Structure design HUB 0.02A

75.0 25.0

A

Base:

750.0

Is a square frame of L angle or box structure of 750 Sq. Frame to Hub Welding

A hub is welded to the frame at the centre, with a perpendicularity of 0.02mm, The hub will have a bore to suit the inner shaft diameter, this is a transition fit with a clearance of 0.1 mm.

Fig.1. 12 Assembly drawing of Hub with the frame

Step 3.


10


Structure design

HU B 75.0 25.0

A 750.0

Lock Nut Inner Shaft

Inner Shaft

Outer Shaft

Is a Hallow pipe, in the bottom the shaft is turned to 3 steps, 1 to suit the bearing ID 2 to suit the hub IB 3 there is a threaded portion in the end for a lock nut to lock in position.

Is a Hallow pipe, with two bearing seating's on top and bottom this is the only support for the shaft, and it revolves freely on the inner shaft

Fig.1. 13 Assembly drawing Hub, lock nut, shaft housing

Step 4. Mounting of the belt between Rim & the pulley

Belt Drive

Outer shaft to cycle rim welding

Lager Pulley is welded to the outer shat with a concentricity of 0.05mm Then smaller pulley is mounted on the mounting plate, Shims are used for the adjustment of the centre height and tensioning. A flat belt is used for connection

Larger Pulley Belt Shim Smaller Pulley Mounting Plate 0.0 2A

75.0 25.0

A 750.0

Fig.1. 14 Belt mounting between rim and the pulley

Step 5. Assembly of shaft, with Rim, Bearing & lock nut Vertical Axis Wind Turbine

11


Bearing Cover Bearing Outer Shaft

Larger Pulley Belt Bearing

Shim Smaller Pulley

Spacer 0 . 9

Mounting P late

HUB 0.02A

75.0 25.0

L-Plate Lock Nut Frame A

750.0

Inner Shaft

Fig.1. 15 Assembly of Hub, Bearing, Rim, lock nut and the pulley with plate support

Step 6 : Blade mounting

Typ 12

0 . 0 5

Ø6

Ø12

0 . 5 2 2

0 . 0 5

M6

Ø12

0 . 5 2 2

0 . 5 2 2

0 . 5 2 2

0 . 5 2 2

Fig.1. 16 Blade mounting


12


Step 7: Assembly of hub A 2 0 . 0

0.00 0.02

Ø24.00

0.02 A

0 . 0 5

The top face must have a perpendicularity of 0.02 with respect to the bore.

Ø28.00

0 . 0 0 2

Hub: Material is mild steel, The bore of 24 has a close tolerance of - 0.02,

0 . 0 5

There is relief in between to reduce the are of contact,

A 0.00 0.02

Ø24.00

Ø65.00

The top bore must be concentric to the bottom bore by 0.02mm Fig.1. 17 Hub Assembly

Step 8: Assembly of shaft housing with the main shaft A 2 0 . 0

Ø25.00

Manufacturing drawings

0.02 A

To suit Bearing ID 25

0 . 9

Ø28.00

0 . 9

Material is mild steel, The overall OD is maintained as 28 mm Bottom there are threads to suit lock nut a nd is maintained as M24 X 1.5 There is a dia of 24 to suit the hub and there is a tolerance of 0.02 Then there is bearing seating to suit bearing ID of 25 mm, the perpendicularity has to be maintained Towards the other end there is a bearing seating for 25mm the concentricity w.r.t to other bearing seating and perpendicularity has to be maintained

Ø25.00

A A

Inside shaft:

1300

2 0 . 0

0 . 5 2 2

0 -0.02

Ø24.00

0 . 5 2

Ø16.00 M24.00X1.5

6 To suit with lock nut Fig.1. 18 Shaft housing assembly


13


Step 1: Table 1. 3

Parts

Hub

Lathe

Milling

Machine

Machine

Turning

Drilling/

Welding

Assembly

Tapping

to

Drilling,

the required

Reaming.

size.

Lock Nut

Turning

to Milling

the requir ed

of

slots.

Dimension.

Bushes

Turning

Welding of bushes for blade mounting

Hub to Frame

Welding of Hub to the frame.

Pulley, I-Plates For Dynamo

Turning for Milling for Drilling for making pulley


I-plates.

pulley,Iplates.

15


Step 2: Table 1. 4 Parts

L athe

Milling

Welding

Assembly

Machine Hub

Positioning of the hub

Frame

Supporting

ribs

to frame

Bushes

Setting

bushes

for

Blade

mounting

Shaft to Frame

Shaft

mounting

to the Hub and Frame

Lock nut to shaft

Lock nut to the inner shaft.


16


1.6 Design Errors. There was a design error in the belt drive system that was identified at the assembly stage, there was no bearing support provided at the smaller pulley connected to the dynamo(highlighted in red), and the smaller pulley was directly mounted onto the dynamo shaft, due to the belt forces the shaft of the dynamo was getting bent and the alignment of the smaller puller w.r.t to the larger pulley (cycle rim) could not be achieved and the belt used to get slipped during the operation of the turbine,

Fig.1. 21 Bladeand Pulley mounting

1.7. Improvement identified The pulley has to be supported with a bearing support and the shaft of the dynamo is screwed onto the pulley, so that the load acting on the pulley is transferred to the bearing and no load is transferred to the dynamo shaft also the alignment or the parallelism of the smaller pulley with respect to the larger pulley can also be achieved.

1.8. Estimated Cost of the project o

Material cost:

Rs 6500.00

o

Machining Cost:

Rs 6150.00

o

Fabrication Cost:

Rs 7300.00

o

Miscellaneous:

Rs o


550.00

Total =Rs. 20,500

17


Conclusion The development of Vertical Axis Wind Turbine gave us experience in the design, fabrication and field testing. Savonius turbines are one of the simplest turbines. Aerodynamically, they are drag-type devices, whit such large devices it is quite feasible to have adequate control systems for starting and controlling the system. In India, however, the mean wind speeds are generally so low that it is unlikely that wind power can be economically converted to electric power for grid augmentation. The most practical use for wind power is likely to be direct water pumping for drinking water and minor irrigation purposes. The water pumping application generally implies high starting torque and low control costs. Hence it appears at least from general survey that Savonius turbines arc not likely to be of much use in the Indian context.


18


Future Scope The first generation household turbine which has been manufactured appears to be rather large and heavy for the purpose of fixing it to the roof or chimney of a domestic property. However, this design would be suitable for commercial buildings. With some modifications to the frame, this type of windmill could feasibly be used with the home in mind. Many good features of this design were seen, namely: reliability; it is easy to manufacture; has no yaw mechanism; is of a low cost; and has self starting availability. Furthermore the build process has highlighted several improvements which are to be implemented by the author in the development of the next generation of household turbine. These enhancements are listed below. ¾

Produce a more compact/lighter wind turbine for easy transportation.

¾

Use a telescopic metal frame for reduced weight and size.

¾

Use a permanent magnet generator or produce a custom made generator.

¾

Improve the aesthetic appeal by using clear blades.

¾

Small Savonius wind turbines can be used as advertising signs where the rotation helps to draw attention to the item advertised. They sometimes feature a simple two-frame animation.

¾

Connect the wind turbine directly to the mains within the home.

¾

Use an inverter to adjust the 12 volt DC to mains supply (240 volt AC) thus opening up more household applications.

¾

Increase the gear ratio so that the turbine has the potential to spin faster.

¾

Add a braking mechanism to stop the rotor in gale force winds . [2]


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Ref er ences [Referring a Book] [1] Joachim Peinke, Peter Schaumannand Stephan Barth (Eds.) Wind Energy Institute of Physics, 26111 Oldenburg, University of Hannover, Institute for Steel Construction. Appelstrasse 30167 Hannover [Referring a Journal paper] [2] Dr. Gary L. Johnson, Wind Energy Systems November by 21, 2001

[Referring a Thesis] [3] P.N. SHANKAR, Development of vertical axis wind turbines, National Aeronautical Laboratory, Bangalore 560 017 [Referring a website] [4] Unknown- http://wind.nrel.gov/public/library/11045.pdf Retrieved on 25-05-2011 [Software] [5] www.catia.com


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Vertical Wind Turbine Thesis

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