Review Paper on Wind Turbine

Transcription

1 International Journal of Researh (IJR) Available at Review Paper on Wind Turbine Harish Kumar Patel 1 ; Vipinkumar patel 2 ; Ashwani Sahu 3 & Kusum Sahu 4 1 Leturer & Head of Department of Mehanial Engineering, Government Polytehni Jashpur (Chhattisgarh), harish.patelhydra@gmail.om 2 Leturer, Government Polytehni Jashpur (Chhattisgarh), -bipin1804@gmail.om 3 Student of Government Polytehni Jashpur (Chhattisgarh), -oolsuraj.sahu104@gmail.om 4 Student of Government Polytehni Jashpur (Chhattisgarh), -kusumsahu357@gmail.om ABSTRACT This paper presents advantageous onept of the present day situation, energy is a foremost neessity for human life. A wind turbine is a gadget whih onverts the kineti energy of wind into mehanial energy. This mehanial energy an be used for many fields (suh as grinding grain or pumping water) or for driving a generator that onverts the mehanialenergy into eletriity that is supplied to the power grid users here we study of wind energy through the wind turbine mehanism. There is a must to ultivate non-onventional bases for power generation due to the purpose that our onventional soures of power are attainment sarer by the day. This paper highlights on the knowledge that the kineti energy reeiving wasted while blades move an be used to produe power by using a speial Windmills, wind pumps and sails to propel ships. Wind power as an alternative to fossil fuels, is plentiful, renewable, widely distributed, lean, produes no greenhouse gas emissions during operation, and uses little. This engendered power an be used for general purpose uses like street lights, traffi signals et. For obtaining the eletriity through the wind turbine mehanism a prototype model is developed and studied. Finding from this researh work is disussed in this paper. Key words:-wind Turbine 1.INTRODUCTION If the effetiveness of a wind turbine is improved, then more power an be generated due to thispower weredue the need for expensive power generators that ause atmospheri pollution. This would also dereasethe ost of power for the people. Power an be generated and stored by a wind turbine with no pollution. If the effiieny of the ordinary wind turbine is improved and widespread, the ommon people an ut bak on their power osts immeasurably. Ever sine the Seventh Century people have been develop the wind turbine to generate eletriity to make their lives easier. The whole onept of windmills is first originated in Persia. In the beginning people used the wind blades to irrigate farm land, rush grain and milling. This is probably where the word windmill ame from. Sine the extremely use of windmills in Europe England and Frane during the Twelfth Century, some plae suh as the Netherlands have prospered from reating vast wind farms. It is belief that windmills were not very reliable or energy effiient. Only half the sail rotation was utilized.early 200 B.C. China used windmills to transport water and make grain they were usually slow and had a low tip speed ratio but were useful for transport. Sine its reation, man has regularly tried to develop the windmill. As a result, over the years, the number of blades on windmills has derease. Most modern windmills have 4-6 blades while past windmills have had 8~12blades. Old modern of windmill was operate by hand, while present windmills an be automatially turned into the wind. The sail design and materials used to reate them have also developed over the years. There are various types of windmills, suh as: the tower mill, Durries, sail windmill, sok mill, multiblade, water pump, spring mill, savonius, yloturbine, and the lassi four-arm windmill. All of the above windmills have their advantages. Some Available online: P a g e 542

2 International Journal of Researh (IJR) Available at windmills, like the sail windmill, are slow moving have a low speed ratio and are not very energy effiient ompare to the ylo-turbine. There have been many developments in the field of windmill over the years. Windmills have been apable of air breaks, to ontrol speed in strong winds. Some vertial axis windmills have even been use with hinged blades to avoid the stresses at high wind speeds. Some windmills, like the ylo-turbine, have been apable with a vane that senses wind diretion and auses the rotor to rotate into the wind. Wind turbine generators have been apable with gearboxes to ontrol [shaft] speeds. Wind turbines have also been apable with generators whih onvert shaft power into eletrial power. But above all of these improvements in the field of windmill, the most important improvement to the windmill was made in 1745 when the fantail was invented. The fantail automatially rotates the sails into the wind. 2. LITERATURE SURVEY The knowledge of availability of required omponents and their working is essential for implementation of the projet. This hapter provides information about the wind mill theory and types whih is important for designing of windmill. Wind turbine aerodynamis must be designed for optimal output to exploit the wind energy. This problem remains both hallenging and ruial. Muh researhes been onduted on Savonius rotors with two semi-ylindrial blades and S-shaped rotors with various flow parameters. Islam et al. [8] researh of aerodynami fores ating on a stationary S-shaped rotor and attempted to predit its dynami performane. They measured the pressure distribution over the surfaes of the blades and found that flow separates over the front and bak surfaes, and the point of separation depends on the rotor angle. They also found that the net torque beomes maximum at a rotor angle of α = 45 and negative while the rotor angleis between α = 135 and α = 165. Diaz et al. [3] analyzed the pull and lift oeffiients of a Savonius wind turbine to quantify the aerodynami performane of the rotor. They found that maximum effiieny, in terms of power oeffiient, ours at a tip-speed ratio of λ = 1, and the drag oeffiient dereases sharply when the tipspeed ratio inreases or dereases from this value. They also found that the most important region of Savonius rotor operation ours at a tip-speed ratio around λ = 1, wherethe lift oeffiient remains as a onstant 0.5. Sawada et al. [15] studied the mehanism of rotation of a Savonius rotor with two semi ylindrial blades and found that a rotor with gap ratio of 0.21 produes positive stati torque at all angles. They also found that lift fore ontributes signifiantly to dynami torque while therotor angle is between α = 240 and α = 330. Aldoss and Obedient [1] used the disrete vortex method to analyze the performane oftwo Savonius rotors running side-by-side at different separations. They ompared their omputational results on torque and power oeffiients with their experimental results for verifiation. Fujisawa and Goth [4] studied the aerodynamidesign and performane of a Savonius rotor by alulating the pressure distributions on the blade surfaes at various rotor angles and tip-speed ratios. They found that the loaddelivered on the rotating rotor differs remarkably from those on the motionless rotor, espeially on the onvex side of the advaning blade, where a low pressure region is formed by the moving-wall effet of the blade. Torque and power performane, evaluated by integrating the load, were in lose agreement with diret torque measurements. Rahman et al. [11-13] experimentally studied aerodynami harateristis, suh as the torque and drag oeffiients, of a three-bladed Savonius rotor model by measuring the pressuredifferene between the onvex and onave surfaes of eah semiylindrial blade of the stationary rotor at different rotor angles and the variation of the separation point with theinrease of rotor angle. They used the stati oeffiients for dynami predition and omparedthe findings in terms of power oeffiient for different tip-speed ratios with experimental resultsfor the twobladed Savonius rotor. Although the starting torque for Savonius rotors is high, it is not uniform at all rotorangles. The torque Available online: P a g e 543

3 International Journal of Researh (IJR) Available at harateristis of an ordinary Savonius rotor have two problems. First, theyvary signifiantly at different rotor angles, ausing the rotor to vibrate and onsequently derease its durability. Seond, the torque at the rotor angle ranging from 135 to 165 and from 315 to345 is negative or very small, whih hinders its use as a starter [6]. To derease this torque variation and advane starting features, a new type of Savonius rotor was designed and fabriated by Hayshi et al. [7]. It had three stages, with a 120 buket phase shift between adjaent stages. With this design, wind-tunnel tests showed that both stati and dynami torquevariations in one revolution were muh smoother ompared to an average one-stage rotor, whihgreatly improved the starting harateristis. They also alulate the torque harateristis of therotors with guide vanes and found that, on the average the guide vanes improved the torque oeffiient in the low tip-speed ratio but dereased it in the high tip-speed ratio. They onluded that two- and three-stage onventional Savonius rotors ould overome the problem of negative torque. However, the maximum power oeffiient dereases for this kind of design with morestages.to derease the variation of stati torque in onventional Savonius rotors with rotor angle ranging from 0 to 360, Kamoji and Kedare[9] tested a helial rotor with a twist of 90. They onduted experiments in an open-jet wind tunnel at gap ratios of 0.0, 0.05, and 0.08 to study theeffet of the overlap ratio and the Reynolds numbers on its performane to evaluate the statitorque, the dynami torque, and the power oeffiients. They ompared its performane with andwithout a shaft between the different overlap ratios and end plate. A helial rotor without a shaftwas also ompared with the performane of the onventional Savonius rotor. They found that allhelial rotors have a positive power oeffiient of stati torque for all rotor angles, but the rotorswith a shaft had a lower power oeffiient than those without. The power oeffiient of the rotorwithout a shaft with a zero overlap ratio was marginally less than the onventional Savoniusrotor. The rotor appeared to be sensitive to the Reynolds number, but this finding must be onfirmed by rigorous experiments.mwilliam and Johnson [10] investigated various Savonius wind turbine models to observe the vortex formation and the effet of the sale of downstream wake using partile image veloimetery (PIV) in a lose loop wind tunnel. In that experiment, they used standard Savonius design (diameter = mm) with two semiirular blades overlapping. The design off these blades inlude deep blade design (diameter = mm), shallow blade design (diameter = 28.04mm), outside J blade design (diameter = mm) and inside J blade design (diameter =31.18 mm). They exeuted the experiment at a onstant 3 m/s wind veloity. They observed thatvortex shedding from the following blade was ommon to all five designs they tested, whih had an effet on the sale of the downstream wake of the rotor. They found that the forward urved blade was the ritial area for external flow and the overlap ratio of Savonius wind turbine blades allows flow from the top blade to enter the bottom blade that redues the negative pressure region behind the blades. Saha et al. [14] fabriated a two-stage Savonius wind turbine by inserting valves on the onave side of the blades. They ompared its performane with a onventional Savoniuswind turbine and found that with valves on a three-bladed turbine, the power oeffiient was higher ompared to a two-bladed turbine for both semi-irular and twisted blades. Without valves, airstrikes the blades and rotates them in a negative diretion. They also varied the number of stages in a Savonius wind turbine and found that the power oeffiient inrease from a one-stage design to a two-stage design but derease from a twostage design to a three-stage design due to inreased inertia. They tested twisted blades of one, two, and three-stages and found that threestagedesigns had a better power oeffiient and the twisted-blade design showed better performane. Gupta et al. [5] ompared a three-buket Savonius wind turbine with a three-buket Savonius Darrieus wind turbine. They found that the power oeffiient of the ombined turbines dereases as the overlap ratio inreases. The maximum power oeffiient of 51% was foundwhere there was no overlap. They laimed that the ombined rotor without overlap, whihshowed 51% effiieny, was the highest effiieny of a Savonius wind turbine at any overlapondition under these test onditions. Available online: P a g e 544

4 International Journal of Researh (IJR) Available at Altan et al. [2] did some experimental studies to improve the performane of thesavonius wind turbine using urtain. They plaed urtain arrangement in front of the rotor in away that is apable of preventing the negative torque that affets the onvex blade surfae of thesavonius wind turbine. Figure2: Curtain positioning of Altan et al. experiment [3] They performed the experiment with urtain and without urtain. They found that optimum urtain angle was α = 45 and ß = 45 where they ahieved the highest poweroeffiient. The numerial value for the power oeffiient was 38% greater than the designwithout urtain. Other urtains also showed that the power oeffiient an be improved by 16% ompared to the design without urtains. 3. WORKING OF WINDMILL Fig- 3 The working of wind mill is very simple as the air omes in the struture, the working blades rotates whih is onneted to main rotor shaft by the supporting arms, the main rotor is oupled to a generator from where we an get the output. The power in the wind turbine an be extrated by allowing it to blow past moving wings that exert torque on a rotor. The amount of power transferred is diretly relative to the mass of the air, the area swept out by the rotor and the ube of the wind speed in wind turbine. The air that travels through the swept area of a wind turbine varies with the wind speed and air density. As an example, on a ool 15 C (59 F) day at sea level, air density is about 1.22 kilograms per ubi meter (it gets less dense with higher humidity). An 8 m/s breeze blowing through a 100 meter diameter rotor would move about 76,000 kilograms of air per seond through the swept area. In wind turbine the kineti energy ofa given mass varies with the square of its veloity. Beause the mass flow wind inreases linearly with the wind speed, the wind energy present to a wind turbine inreases as the ube of the wind speed. The power of the example breeze above through the example rotor would be about 2.5 MW. As the wind turbine extrats energy from the air flow, the air is slowed down, whih auses it to reah out and diverts it around the wind turbine to some extent. At ground level wind veloity is low as ompared to higher level, thus H.A.W.T are installed at higher level plaes. To ontradit this onept, our projet works on the priniple of installing vertial axis savonius wind turbines at ground level itself where wind veloities are atually low but by mounting the wind turbine on moving loomotive, higher wind veloities an be ahieved at ground level whih makes the wind turbine to work in dynami onditions instead of being stationary. Thus the wind turbine is mounted on a loomotive and at various loomotive speeds gradually inreasing wind veloities are obtained. Wind veloity inreases on inrease in loomotive speed. Using these wind Available online: P a g e 545

5 International Journal of Researh (IJR) Available at veloities higher amount of mehanial power is generated whih eventually goes on to generate more eletrial power. 4.SCOPE FOR IMPROVEMENT Design of wind turbine an be studied and modified further for getting more than aurate power requirements. Effets of different materials of blades on speed of wind turbine is to be studied. Different shapes of wind turbine blades are needed to be studied to further enhane the power output. Use of Guide asing, guide blades and hinged doors an be done to provide diretion to inoming wind on the blades and to protet the wind turbine rotor from any kind of external damage. CONCLUSION In onlusion, a wind turbine is a mehanism that onverts the wind kineti energy into eletriity. The major working omponents of a wind turbine are: the gearbox, the rotor, the generator, protetion system, the ontrol, the tower and the foundation. Wind turbines are lassified into two types of lasses: horizontal axis wind turbine and vertial axis wind turbine. The advantage of a Vertial Axis Wind Turbine is that the wind an ome from any diretion; The disadvantage is the height limitations. The major benefit for a Horizontal Axis Wind Turbine is the high effiieny it has; The diffiulty is the maintenane and restore at high altitude. Aerodynamially, the wind turns the rotor blades of the Horizontal Axis Wind Turbine beause of the pressure gap between the top and the bottom of the airfoil. For the Vertial Axis Wind Turbine, it is the pull that ats on the blades and turns the rotor blades. Today, wind power is eonomially ompetitive ompared to traditional energy beause the ost of wind turbines is getting heaper beause of tehnology development. Wind energy is also a renewable and pollution free energy whih an help us redue the emissions of greenhouse gases. I believe that wind energy an beome an important asset to solve limate hange and global warming issues in the future. REFERENCES [1] Aldoss, T.K. Obeidat, K. M. :Performane analysis of two Savonius rotor Running side by side using the disrete vortex method, wind Engineering, 11, (1987). [2] Altan, B.D., Atilgan, M, Ozdamar, A. : An Experimental study on improvement of a savonius rotor performane with urtaining. Experimental thermal and fluid siene. 32, (2008). [3]Diaz, F, Gavalda, J., Massons, J. : Drag and lift oeffiients of the savonius wind Turbine, Journal of wind engineering. 15, (1991). [4] Fujisawa, N, Gotoh,F. : Experimental study on the aerodynami performsne of a Savoniusrotor, ASME Journal of solar energy engineering, 116, (1994). [5] Gupta, R, Biswas, A, Sharma, K.K. : Comparative study of a three bukets savonius rotor with a ombined three buket savonius three bladed darrieusrotor. Renewableenergy. 33, (2008). [6] Hayashi, T, Li, Y, Hara, Y, Suzuki : Proeedings of European Wind Energy Confereneand Exhibition, Wind tunnel test on a three stage out phase savonius rotor, London, England. (2004). [7] Hayashi, T, Li, Y, Hara, Y. : Wind tunnel tests on a different phase three stage savoniusrotor. JSME international journal, 48,9-16. (2005). [8] Islam, A.K.M.S., Islam, M.Q., Razzaque, M. M., & Ashraf, R : Stati torque and Drag Charateristis of an S-shaped Savonius Rotor and predition of Dynami Charateristis, Wind Engineering, 19. (1995). [9] Kamoji, M. A. Kedare, S.B. : Proeedings of 5 th AIAA International energy Conversion Engineering Available online: P a g e 546

6 International Journal of Researh (IJR) Available at Conferene. Wind tunnel tests on a single stage helialsavonius rotor. (2007). [10] MWilliam, M, Johnson, D.A. : Veloity measurement of flow around modelvertial axis wind turbines. International Journal of Green Energy. 5, (2008). [11] Rahman, M., Islam, M. Q., Islam, A.K.M.S. : Proeeding of the third international onferene on fluid mehanis and heat transfer. Predition of dynami harateristis of a three bladed Savonius rotor.(1999). [12] Rahman, M. :Torque and drag harateristis of a three bladed Savonius rotor, M. S. Thesis, Meh. Eng. Dept.,Bangladesh University of Eng.And Teh., Bangladesh. (1999). [13]Rahman, M., Islam, M. Q., Islam, A.K.M.S. :Proeeding of the 2 nd int.seminar on renewable energy for poverty alleviation, IEB, Bangladesh,Aerodynami harateristis of a three bladed Savonius rotor.(1999). [14] Saha, U. K., Thotla, S., Maity, D. :Optimum design onfiguration of Savoniusrotor through wind tunnel experiment.journal of windengineering and industrial aerodynamis. 96, (2008). [15] Sawada, T., Nahamura, M., Kamada, S. :Blade fore measurement and flow visualization of Savonius rotors, Bulletin of JSME, 29, (1986). Available online: P a g e 547