savonius wind turbine design and validation-an ......axis wind turbine is the best option for the...

http://www.iaeme.com/IJMET/index.asp 18 [email protected]

International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 9, September 2017, pp. 18–25, Article ID: IJMET_08_09_002

Available online at http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=9

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication Scopus Indexed

SAVONIUS WIND TURBINE DESIGN AND

VALIDATION-AN MANUFACTURING

APPROACH

M. Sunil Kumar

Assistant Professor Department of Mechanical Engineering,

Institute of Aeronautical Engineering, Dundigal, Hyderabad, India

VVSH Prasad

Professor Department of Mechanical Engineering,


C. Labesh Kumar

Assistant Professor Department of Mechanical Engineering,


Dr. K Ashok Reddy

Professor Department of Mechanical Engineering MLR Institute of Technology,

Hyderabad, India

ABSTRACT In recent era, research and development activities in the field of renewable energy,

especially wind and solar have been considerably increased, due to the worldwide

energy crisis and high global emission. The horizontal axis wind turbine cannot be

used for house hold purpose. So, Savonius vertical axis wind turbine can be better

option as it operate in low wind condition also. The choice for this model is to show

case its efficiency in varying wind conditions as compared to the traditional horizontal

axis wind turbine and contribute to its steady growing popularity for the purpose of

mass utilization in the near future as a reliable source of power generation. The paper

aims at designing and analysis of savonius wind turbine which can be used to

generate electricity from wind energy. Therefore, objective is to increase efficiency at

low maintenance price without affecting the whole unit.

Keywords: Renewable energy, VAWT, Savonius, Dynamo, Household

Cite this Article: M. Sunil Kumar, VVSH Prasad, C. Labesh Kumar and Dr. K Ashok

Reddy, Savonius Wind Turbine Design and Validation- an Manufacturing Approach,

International Journal of Mechanical Engineering and Technology 8(9), 2017,

pp. 18–25.

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=9

Savonius Wind Turbine Design and Validation- an Manufacturing Approach


1. INTRODUCTION

Savonius wind turbines are a type of vertical-axis wind turbine (VAWT), used for converting

the force of the wind into torque on a rotating shaft. The turbine consists of a number of

aerofoils, usually—but not always—vertically mounted on a rotating shaft or framework,

either ground stationed or tethered in airborne systems. Savonius turbines are one of the

simplest turbines. Aerodynamically, they are drag- type devices, consisting of two or three

scoops. Looking down on the rotor from above, a two-scoop machine would look like an "S"

shape in cross section. Because of the curvature, the scoops experience less drag when

moving against the wind than when moving with the wind.

The differential drag causes the Savonius turbine to spin. Because they are drag-type

devices, Savonius turbines extract much less of the wind's power than other similarly-sized

lift-type turbines. Much of the swept area of a Savonius rotor may be near the ground, if it has

a small mount without an extended post, making the overall energy extraction less effective

due to the lower wind speeds found at lower heights. Savonius turbines are used whenever

cost or reliability is much more important than efficiency. For example, most anemometers

are Savonius turbines, because efficiency is completely irrelevant for that application.

Much larger Savonius turbines have been used to generate electric power on deep-water

buoys, which need small amounts of power and get very little maintenance. Design is

simplified because, unlike with Horizontal Axis Wind Turbines (HAWTs), no pointing

mechanism is required to allow for shifting wind direction and the turbine is self-starting.

Savonius and other vertical-axis machines are good at pumping water and other high torque,

low rpm applications and are not usually connected to electric power grids. They can

sometimes have long helical scoops, to give smooth torque. The most ubiquitous application

of the Savonius wind turbine is the Flattener Ventilator which is commonly seen on the roofs

of vans and buses and is used as a cooling device. Small Savonius wind turbines are

sometimes seen used as advertising signs where the rotation helps to draw attention to the

item advertised. They sometimes feature a simple two-frame animation.

2. METHODOLOGY

During design of Savonius vertical axis wind turbine a few factors are consider for design and

based on this for input data whole design calculations were carried out. The following factors

are considered during design.

d – diameter of blade [m]

D –diameter wing spread of rotor [m]

e – pipe spacing [m]

h – height of blades [m]

v – wind speed [m/s]

F – diameter of end plates [m]

Cp - Betz coefficient

a- sweep area of the rotor blade [mm2]

n- speed of rotor [rpm]

�- radius of the rotor [mm]

�- angular velocity [rad/sec]

λ - tip-speed ratio.

��-the torque at the rotor shaft [Nm]

ρ- air density[kg/m3]

M. Sunil Kumar, VVSH Prasad, C. Labesh Kumar and Dr. K Ashok Reddy


��- power of the rotor [w]

FORMULAE & CALCULATIONS

Assume diameter of blade d = 30mm

(Reference: F. Sigernes, University Centre in Svalbard (UNIS), Norway)

Then, e =d/3 =30/3= 10mm

D=5e =5*10 = 50mm

f = 1.2D = 1.2*50 = 60mm

h= 1mm

The maximum power of the rotor is estimated according to Betz’s law

��= 1/2 �∙� ∙ �3∙ �

=0.36∙ ℎ∙ ∙�3. [W]

Where, ρ=1.2 kg/m3 is the air density,

�=ℎ∙ the sweep area of the rotor blade and Cp=0.593 the Betz coefficient.

However, there are aerodynamic and mechanical losses in the order of 50%. Our rotor

shaft power equation then becomes

��=0.18∙ ℎ∙ ∙�3. [W]

= 0.18*1*50*6*6*6

=12.95 w

The rotational speed is defined as �= (60/2π×�) [rpm]

Where, =�∙�/� is the angular velocity in units of radians per second,

=1*6/25

=36.04 rad/s

Here �=/2 the radius of the rotor

=50/2

= 25mm and

λ = 1 the tip-speed ratio

Then n = (60/2π×�)

= (60/2π * 30.04)

= 344rpm

Furthermore, the torque at the rotor shaft is given as = �/�. [Nm]

=12.95/36.04

=0.36 Nm

The height of the rotor is h=1m. The wind start speed v =6 m/s.

CALCULATION OBTAINED

d 30[cm]

e 10.0[cm]

D 0.500 [m]

r 0.2500 [m]

ω 36.04[rad./s]

n 344[rpm]

�� 12.95 [W]



τs 0.36[Nm]

h 1[m]

v 6[m/s]

Figure 1 Basic Sketch of Savonius Wind Rotor

Figure 2 Assembly drawing of Disc, Shafts and Blades

3. SPECIFICATIONS

DISC DIMENSIONS

Thickness 2.5 mm

Diameter 60mm

BLADE DIMENSIONS

Height 1 meters

Diameter 30 mm

Thickness 1 mm



SHAFT DIMENSIONS

Diameter 25.5mm

Length 1.6meters

BEARING DIMENSIONS

Diameter 25.1mm

Type ball bearing

GEARS DIMENSIONS

Gear diameter 210mm

Thickness 25mm

4. CFD ANAYSIS

Figure 3 Design Modular

Figure 4 Set up

Figure 5 Mesh



5. RESULTS AND DISCUSSIONS

Figure 6 fluid flow

Figure 7 Momentum and Mass

Figure 8 Turbulence

Figure 9 Pressure



Figure 10 Velocity

Figure 11 Temperature

Discussions drawn from above results At least 10% power of the consumption can be

fulfil by this set up. Multi stage generator is the double generation concept with the same size

rotor. Gear arrangement can increase the number of rpm in case of low wind speed. This

turbine is generally suitable for 8 to 10m of height above ground level. Because at ground

level velocity of air is very less. Combination of alternator with gear arrangement can be used

to increase output but unnecessarily it will increase the cost of machine. The all-weather point

of view the material use should be non-corrosive. The alternate option for turbine blade

material is reinforced glass fiber because of its more elastic nature but it is costlier than

Aluminium alloy. The cost of the machine should be as minimum as possible. So that it will

be economical for everyone to purchase.

6. FABRICATED SAVONIUS WIND TURBINE



7. CONCLUSION

Such type of wind turbine is more important for small scale work as well as industrial work in

less cost and more efficiency. The machine capacity can be increased according to the need.

By its design the defects can be easily overcome. Simpler design not only reduces the defects

but also contributes for generation of power. It should be noted that these turbines can also be

used for commercial purposes by adding more blades to the turbine. The objective of the

study is to increase the efficiency of the turbine. These portable turbines can also be used for

irrigational unit and also to generate electricity for small scale industry. There are number of

sources for generation of power but in the recent years wind energy shown its potential as the

clean source of energy and contributing to the high energy demands of the world. Vertical

axis wind turbine is the best option for the area which is under load sheading. The output from

the turbine is use to charge a heavy duty battery. This can be beneficial than inverter back up.

REFERENCES

[1] Moutsoglou A, Weng Y. Performance tests of a Benesh wind turbine rotor and a Savonius

rotor. Journal of Wind Engineering 1995; 19: 349-362

[2] Kroms, Wind Power Stations Working in Connection with Existing Power Systems. 1954,

A.S.E.Bull. p. 135-144.

[3] Hütter, U., the Development of The Wind Power Installations for Electrical Power

Generation in Germany. 1973, NASA Technical Translation: Washington DC.

[4] Small-scale wind energy, in Policy insights and practical guidance (CTC738), F.a.R.A.

Department for Environment, Editor. 2008, Carbon Trust and Met Office.

[5] Abhilasha Rathod, Nalin Raut, Sai Patil, Kajol Kamble, Shailendra Shisode, Aerodynamic

Analysis of Morphing Blade for Horizontal Axis Wind Turbine. International Journal of

Mechanical Engineering and Technology, 8(1), 2017, pp. 37–44

[6] Gayathri.S.Nair and Krishnakumari.T, Comparison of Crowbar Control and Novel

Control Methods for Dfig Wind Turbine to Enhance Lvrt Capability under Various Faults,

INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING & TECHNOLOGY

(IJEET), Volume 5, Issue 12, December (2014), pp. 14-20

[7] M. Natesan, Dr. S. Jeyanthi and U. Sivasathya, A Review on Design of Augmented Wind

Turbine Blade for Low Wind Speed Urban Area, International Journal of Mechanical

Engineering and Technology (IJMET) Volume 8, Issue 7, July 2017, pp. 685-691

[8] Martin Best, A.B., Pete Clark, Dan Hollis, Doug Middleton, Gabriel Rooney, Dave

Thomson and Clive Wilson, Small-scale Wind Energy – Technical Report, in Urban Wind

Energy Research Project Part 1 – A Review of Existing Knowledge. 2008.

[9] Hau, E., Wind Turbines. 2nd ed. Fundamentals, Technologies, Application, Economics.

2006, Berlin: Springer.

[10] Bruce E. Boatner, E.R.D., Eagle, ID (US) 83616, Vertical Axis Wind Turbine with

Articulating Rotor. 2010: United States. p. 32.

[11] Joushua Yen, Noor Ahmed. University of New South Wales (NSW) Sydney, Australia.

Sciencedirect (Procedia engineering 49 (2012) 99-106).Improving safety and performance

of small-scale vertical axis wind turbines.

[12] Murat Islam .A MS candidate, School of Aerospace, Mechanical and civil Engineering.

University of Manchaster, England. Design and development of micro wind turbine.

[13] G.D.Rai, Renewable energy sources, book.

[14] Blackwell BB, Sheldahl R, Feltz LV. Wind Tunnel Performance Data for Two and Three

Bucket Savonius Rotor. Journal of Energy 1978; 2:160-164.

[15] Le Gourieres D. Wind Power Plants Theory and Design; Pergamon Press Ltd, 1982.

savonius wind turbine design and validation-an ......axis wind turbine is the best option for the...

Documents