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Design of vertical axis wind turbine for harnessing optimum power
 

Design of vertical axis wind turbine for harnessing optimum power

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    Design of vertical axis wind turbine for harnessing optimum power Design of vertical axis wind turbine for harnessing optimum power Document Transcript

    • INTERNATIONALMechanical Engineering and Technology (IJMET), ISSN 0976 – International Journal of JOURNAL OF MECHANICAL ENGINEERING 6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME AND TECHNOLOGY (IJMET)ISSN 0976 – 6340 (Print)ISSN 0976 – 6359 (Online) IJMETVolume 4, Issue 2, March - April (2013), pp. 172-177© IAEME: www.iaeme.com/ijmet.aspJournal Impact Factor (2013): 5.7731 (Calculated by GISI) ©IAEMEwww.jifactor.com DESIGN OF VERTICAL AXIS WIND TURBINE FOR HARNESSING OPTIMUM POWER 1. M.Z.I.Sajid 2. Dr. K. Hema Chandra Reddy 3. Dr.E.L. Nagesh 1 Quba College of Engineering & Technology, Nellore, Andhra Pradesh (India) 2 Registrar, JNTUA Anantapur. Andhra Pradesh (India) 3 Principal Netaji Institute of Engg. & Tech. Hyderabad, Andhra Pradesh (India) ABSTRACT Construction of vertical axis wind turbine has been carried out and experiments were conducted on models simulating slope or wind reducer in a slow speed wind tunnel. The wind energy depends on wind velocity. For a 300 slope wind reducer wind velocities were recorded at various heights. Simultaneously, measurements of the velocities were made at equal heights on plain surface. A micro-mini vane anemometer was used for wind power measurements. Details of the experimental results and theoretical explanation are presented. The results show that wind speed increases with reducer starting with 1.35 times at the top of the reducer. The maximum increase is noticeable at about 300 slopes. Therefore a typical wind mill constructed about 10 feet height, 300 slope and 10 feet length since the power is increased by 3.38 times. KEY WORDS: Concave shaped slope wind reducer, Efficiency, Sloping structure, Vertical axis windmill and Wind power. 1. INTRODUCTION The wind energy depends on wind velocity. Wind velocities at different heights were expressed in terms of the corresponding available velocities at equal heights with and without reducer turbines. The results show that wind speed increases with reducer, starting with 1.35 times at the top of the reducer. The maximum increase is noticeable at about 300 slopes. Therefore it is constructed a typical wind mill about 10 feet height, 300 slope and 10 feet length. Wind energy shall serve as foundation stone and a driving force for the immediate 172
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEMEapplication of a world energy system driven by renewable energies to supplement fossil andnuclear sources. In the Annual 11th World Wind Energy Conference 2012 "CommunityPower – Citizens’ Power" held in Bonn, Germany, 2012. The conference covered all aspectsof wind utilization, related policies, manufacturing, development, operation as well aseconomic and social issues, with a special focus on how to involve citizens in renewableenergy and mobilize them as active beneficiaries. India is the fifth largest primary energyconsumer and fourth largest petroleum consumer after USA, China, and Japan. Despite theglobal economic crisis, India’s economy is expected to grow at 6 to 8 % per year. There is anextreme dependence on fossil fuels like oil, coal and natural gas with considerable risks andenvironmental issues.2. THEORETICAL ANANLYSIS In general, the value of wind speed mentioned in meteorological data is at a heightabout 12.2 meters and this is taken into consideration while calculating the possible windpower that may be tapped. To know the real gain in field, wind speed has to be found withrespect to the above value. The calculated values are plotted along with a wind profile over aplain turbine. From the graph it can be seen that the maximum gain is about 1.5 and hence thepower (1.5)3 = 3.38. To find an answer for frequent directional changes in wind, further experiments werecarried out a curved (concave shaped) 300 model and symmetrical triangular 300 model. In thecurved model wind velocities were measured at the extreme ends and the middle, the increasewas found to be almost sane (about 1.5 times) at about half of the height. The triangularmodel gave an increase in wind speed of about 1.4 times at half of the height. These resultsshow that in coastal areas where wind direction changes in the day and night, symmetrical300 wind reducer can be utilized. In areas where frequent changes in wind direction occur,curved wind reducer will be useful. In further experiments a 300 slope model with partialslant portion gave an increase in wind speed of about 1.3 times. The latter experimentalresults may be useful to increase wind speed at the existing windmill sites. Slope ( θ) Vs Wind Velocity (m/s) 8 6 4 2 0 0 10 20 30 40 50 Fig.1 Slope Vs Velocity 173
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME Velocity (m/s) Vs Wind Power (Watts) 500 400 300 200 100 0 5 5.8 6.1 6.5 7.5 7.3 7.2 7.1 6.8 Fig.2. Velocity Vs Wind power Wind Speed Vs Height of The Escarpment 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0 0.2 0.4 0.6 0.8 1 1.2 Fig.3. Wind Speed at Different Heights over the Reducer. In choosing Glass reinforced plastic for the sloping structure the following advantageswere taken into consideration. Glass reinforced plastic is abundantly available in anydeveloping countries. In a bid to find a cheap material to make sloping structures Glassreinforced plastics has been chosen. Glass reinforced plastic wind reducer will help to givesmoothness prevents it from rain and also corrosion resistance. Some studies by researchersreveal, Glass reinforced plastic have been tested and found to have half of the yield strengthof mild steel. It was found that reinforced plastic slab can be designed like steel reinforcedconcrete taking permissible tensile strength and bond strength as 24,000 KN/m2 and 350 KN/m2 respectively. Glass reinforced plastics have been used for windmill blades in Thailand. 174
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME3. PRACTICAL AND ECONOMIC FEASIBILITY To see the effect of 300 slopes on wind speed, experiments were carried out by placingslopes of different roughness before a model windmill and increase in wind speed has beenfound to be substantial. Though full scale field tests are yet to be conducted, the results ofBowen and Lindley show that there is good agreement between full scale field measurementsand wind tunnel. Bowen and Lindley conducted field tests on a 13 m high and 260 slopingescarpment. Hence, it is felt that variation in increase in wind speed as was found on asloping model in wind tunnel.4. THEORETICAL EXPLANATION OF FLOW OVER WIND REDUCER To predict the change in wind distribution connected with changes in surfacetopography, a method has to be evolved which will help in the design of structures. Usuallythe existing codes of practice suggest rules for modifying the design wind profile above hills,but some measurements have shown such hills, but some measurements have shown suchempirical formula are unreliable. Hence, the need for simple theoretical solutions toboundary-layer flows over surface obstacles. A theory which explains the general features ofthe effect of a two dimensional surface hump on a turbulent boundary by Jackson and Hunt.In further studies Jackson modified the above theories to be applicable to carious escarpmentshapes. According to Jackson, as the vorticity in the outer part of the boundary layer is small,one can expect the disturbance to the flow there to be approximately irrational. This impliesperturbation caused by a change in surface topography has exactly the same distribution asthe perturbation to a uniform, in viscid flow caused by the same surface shape. Then thesurface can be found using ordinary irrotational theory. Near the surface, changes in viscousand Reynolds stresses are also to be taken into account. It can be shown that the thickness ofthe layer in which stress changes are important is much less than that of the boundary layer,so that close to the boundary layer in which stress changes are important is much less thanthat of the boundary layer, so the problem of an inner boundary layer being driven by aninner boundary layer being driven by an externally generated pressure gradient. Methods todeal with the above problem are available. There is fairly good agreement at height (between19 and 22m) and at other heights some variation is noticeable. A satisfactory explanation forthe variation in theoretical and experimental results is difficult for the simple reason thatsome factors were left out in the calculations of experimental results for lack of sophisticatedinstruments. Nevertheless the theory gives a broad picture of the prediction technique of windover wind reducer. There is still scope prediction Fig.4. Dimensions of Cone (Reducer) Fig.5. Cone (Reducer) 175
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEME Fig.6. Dimensions of Blade Fig.7. Blade Fig.8. Wind Mill Shaft Fig.9. Wind mill assemble5. RESULTS AND DISCUSSIONS The existing design of vertical axis wind turbine has low efficiency the modifiedreducer with aerodynamic profile increased the efficiency to considerably. The calculatedvalues are plotted along with a wind profile over a plain turbine. From the graph it can beseen that the maximum gain is about 1.5 times and hence the power is (1.5)3 = 3.38. 6. CONCLUSION It can be concluded after the completion of this work that these vertical axis windturbines are more suitable for house hold purposes than the horizontal wind turbines and theycan work with a very low wind speed coming from all the directions making them suitable forurban areas. Till now the Savonius turbine is used for low power generation requirements butby putting the reducer in this turbine it could be used for large scale power generations alsobecause of increasing the wind velocity it works more effectively than the classical Savoniuswind turbine in large scale power generations. 176
    • International Journal of Mechanical Engineering and Technology (IJMET), ISSN 0976 –6340(Print), ISSN 0976 – 6359(Online) Volume 4, Issue 2, March - April (2013) © IAEMEREFERENCES[1] Bowen A.J. and D.Lindley, “measurements of the mean wind flow over variousescarpments.[2] Shapes”, Christ church, dec.1974, 211-219. Gupta R, Das R & Sharma K K,“Experimental study of savonius – Darrieus wind machine,” Department of MechanicalEngineering, National Institute of Technology, Silchar, Assam, India[3] Hiroshi Imamura, Daisuke Takezaki, Yutaka Hasegawa, Koji Kikuyama and KouheiKobayashi, “ Numerical analysis of a local angle of attack to HAWT rotor blade in unsteadyflow conditions “, Department of Mechanical Engineering, Nagoya University, Furo-Cho,Chikusa- ku, NAOGYA, 464-8603, Japan[4] Percival M. C, Leung P.S Datta P.K, “ The development of vertical turbine for domesticelectricity generation”, University of Northumbria, School of Engineering, UK.[5] Tsutomu Hayashi 1, Yan Li2, Yutaka and Katsuya Suzuki 3, “Wind Tunnel test on athree stage out phase savonius rotor”, Department of Applied Mathematics and Physics,Faculty Engineering, Tottori University, 4-101 Koyama- cho Minami, Tottori, Japan; 2Graduate school of Engineering, Tottori University; 3 Department of Applied Mathematicsand Physic, Faculty of Engineering ,Tottori University[6] Suresh Babu K, Subba Rju N V, Srinivasa Reddy M, Nageswara Rao D, “The materialsection for typical wind turbine blades using a medium approach and analysis of blades”,MCDM2006, chania, Greece, June 19-23, 2006.[7] Seon-Hwan Cheong (1), Seong-Date Choi (1), Alexander Mag-isa (2), Myoung-Su Choi(2), “ Optimum Design of Helix Angle for Self-starting VAWT’s”, (1) School of MechanicalEngineering, Graduate School, Kumoh National Institute of Technology.[8] Navin Kumar Kohli, “Performance Prediction in HAWT Wind Power Turbine”International Journal of Mechanical Engineering & Technology (IJMET), Volume 2, Issue 2,2011, pp. 14 - 24, ISSN Print: 0976 – 6340, ISSN Online: 0976 – 6359.[9] R.Saravanan and K.K.Padmanabhan, “Design and Techno- Economic Evaluation of SmallWind Turbine Usage in Indian Power Systems”, International Journal of MechanicalEngineering & Technology (IJMET), Volume 3, Issue 1, 2012, pp. 127 - 141, ISSN Print:0976 – 6340, ISSN Online: 0976 – 6359.[10] T.Vishnuvardhan and Dr.B.Durga Prasad, “Finite Element Analysis and ExperimentalInvestigations on Small Size Wind Turbine Blades”, International Journal of MechanicalEngineering & Technology (IJMET), Volume 3, Issue 3, 2012, pp. 493 - 503, ISSN Print:0976 – 6340, ISSN Online: 0976 – 6359. 177