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://iaeme.com/Home/issue/IJMET?Volume=8&Issue=9 ISSN Print: 0976-6340 and ISSN Online: 0976-6359

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SAVONIUS 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, Institute of Aeronautical Engineering, Dundigal, Hyderabad, India

C. Labesh Kumar Assistant Professor Department of Mechanical Engineering, Institute of Aeronautical Engineering, Dundigal, Hyderabad, India

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 , especially wind and solar have been considerably increased, due to the worldwide energy crisis and high global emission. The horizontal axis 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 and Validation- an Manufacturing Approach, International Journal of Mechanical Engineering and Technology 8(9), 2017, pp. 18–25. http://iaeme.com/Home/issue/IJMET?Volume=8&Issue=9

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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] 푟- radius of the rotor [mm] 휔- angular velocity [rad/sec] λ - tip-speed ratio. 휏푠-the torque at the rotor shaft [Nm] ρ- air density[kg/m3]

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휌푠- 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

휌푠= 1/2 휌∙퐴 ∙ 푣3∙ 퐶푝 =0.36∙ ℎ∙ 퐷∙푣3. [W] Where, ρ=1.2 kg/m3 is the air density, 퐴=ℎ∙퐷 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

휌푠=0.18∙ ℎ∙ 퐷∙푣3. [W] = 0.18*1*50*6*6*6 =12.95 w The rotational speed is defined as 푛= (60/2π×휔) [rpm] Where, =휆∙푣/푟 is the angular velocity in units of radians per second, =1*6/25 =36.04 rad/s Here 푟=퐷/2 the radius of the rotor =50/2 = 25mm and λ = 1 the tip-speed ratio Then n = (60/2π×휔) = (60/2π * 30.04) = 344rpm Furthermore, the torque at the rotor shaft is given as =푃푠/휔. [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]

휌푠 12.95 [W]

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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

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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

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5. RESULTS AND DISCUSSIONS

Figure 6 fluid flow

Figure 7 Momentum and Mass

Figure 8 Turbulence

Figure 9 Pressure

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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

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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

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