Performance Measurement of a Three-Bladed Combined Darrieus-Savonius Rotor

Yıl 2013, Cilt: 3 Sayı: 4, 885 - 891, 01.12.2013

Kaushal Kumar Sharma Agnimitra Biswas Rajat Gupta

Öz

Combination of Savonius and Darrieus type Vertical Axis Wind Turbine (VAWT) rotors possess many advantages over their individual designs, like low starting torque, high power coefficient, low cut-in wind speed etc.  However, there is still a need to do more research on such combination of rotors for their viability in the built environment where wind speed is low. In this paper, an attempt is made to measure the performance of a three-bladed combined Darrieus-Savonius rotor, with Darrieus mounted on top of Savonius rotor, for overlap variations from 10.8% to 25.8%. Power coefficients (Cp) and torque coefficients (Ct) were calculated in a low range of Tip Speed Ratio for each overlap condition. It is found that Cp increases with the increase of overlap. However, there is an optimum value of overlap for which, Cp is maximum, beyond this, Cp starts decreasing. The similar trend is observed for Ct as well. The maximum Cp of 0.53 is obtained at 0.604 Tip Speed Ratio (TSR) for an optimum 16.8% overlap. The performance of the rotor is also compared with another version of this hybrid design with Savonius mounted on top of Darrieus rotor. The present Darrieus-Savonius rotor can be suitably placed in the built environment where it can harness more power from wind and, at the same time, would self-start in low wind condition prevalent in such environment.

Anahtar Kelimeler

Combined Darrieus-Savonius rotor; overlap; low tip speed ratio; power coefficient; torque coefficient

Kaynakça

• Global wind energy market as of 2006. Press release of Global www.gwec.net/publications/global-wind-report-2 (2010 accessed 9 July 2006). Council (GWEC),
• Global wind energy market as of 2010. Press release of Global Wind Energy Council (GWEC), M.H. Model & characteristics of S-rotor wind mills. Wind Engg. J 1988; 12: 59-75. prototype performance
• Grinspan A.S, Kumar P.S, Mahanta P, Saha U.K, Rao D.V.R and Bhanu, G.V. Design, development & testing of Savonius wind turbine rotor with twisted blades. In: 28th National Conference on Fluid Mechanics and Fluid Power, Chandigarh, India, Dec 13-15 2001, pp 428-431.
• Saha U.K and Rajkumar M.J. On the performance analysis of Savonius rotor with twisted blades. Renewable Energy J 2006; 31(11): 1776-1788.
• Modi V.J and Fernando M.S.U.K. On the performance of the Savonius wind turbine. Solar Engg. J 1989; 11: 71- 76.
• Alexander A.J and Holownia B.P. Wind tunnel tests on a Savonius turbine. Industrial Aerodynamics J 1978; 3: 343-351.
• Saylers A.T. Blade configuration optimization & performance characteristics of a simple Savonius rotor. Institute of Mechanical Engineers J 1985; 199: 185-191.
• Blackwell B.F, Sheldahl R.E and Feltz L.V. Wind tunnel performance data for two & three bucket S-rotors. Energy J 1978; 2: 160-164.
• Biswas A., Gupta R., and Sharma KK. Experimental Investigation of Overlap and Blockage Effects on Three- Bucket Savonius Rotors. Wind Engineering J 2007; 31(5): 363-368.
• Darrieus G.J.M. Turbine having its rotating shaft transverse to the flow of the current. Patent application 1835 018, USA, 1931.
• Ali M.E. Estimation of the Performance of the Darrieus-Savonius combined machine. In: Ecologic Vehicles and Renewable Energies, Monaco, Germany, March 26-29 2009.
• Gavalda J, Massons J and Diaz, F. Experimental study on a self adapting Darrieus- Savonius wind machines. Solar & Wind Technologies J 1990; 7(4): 457-461.
• Gupta R., Das, R. and Sharma, K.K. Experimental study of a Savonius-Darrieus wind machine. In: International Conference on Renewable Energy for Developing Washington DC, 2006. University of Columbia, turbine.
• Blackwell B.F, Sheldahl R.E, Feltz L.V. Wind Tunnel Performance Data for Two- and Three-Bucket Savonius Rotors. Report for Sandia Laboratories. Report no. SAND 76-0131, July 1977.