Wells turbine has inherent disadvantages in comparison with conventional turbines: relative low efficiency at high flow coefficient and poor starting characteristics. To solve these problems, the authors propose Wells turbine with booster turbine for wave energy conversion, in order to improve the performance in this study. This turbine consists of three parts: a large Wells turbine, a small impulse turbine with fixed guide vanes for oscillating airflow, and a generator. It was conjectured that, by coupling the two axial flow turbines together, pneumatic energy from oscillating airflow is captured by Wells turbine at low flow coefficient and that the impulse turbine gets the energy at high flow coefficient. As the first step of this study on the proposed turbine topology, the performance of turbines under steady flow conditions has been investigated experimentally by model testings. Furthermore, we estimate mean efficiency of the turbine by quasi-steady analysis.
Cite this paper
S. Okuhara, M. Takao, A. Takami and T. Setoguchi, "Wells Turbine for Wave Energy Conversion —Improvement of the Performance by Means of Impulse Turbine for Bi-Directional Flow," Open Journal of Fluid Dynamics
, Vol. 3 No. 2, 2013, pp. 36-41. doi: 10.4236/ojfd.2013.32A006
 R. Bhattacharyya and M. E. McCormick, “Wave Energy Conversion,” Elsevier, Amsterdam, 2003.
 T. Setoguchi and M. Takao, “Current Status of Self-Rectifying Air Turbines for Wave Energy Conversion,” Energy Conversion and Management, Vol. 47, No. 15-16, 2006, pp. 2382-2396.
 S. Raghunathan, “The Wells Air Turbine for Wave Energy Conversion,” Progress in Aerospace Sciences, Vol. 31, No. 4, 1995, pp. 335-386.
 M. Takao, T. Setoguchi, Y. Kinoue, K. Kaneko and S. Nagata, “Improvement of Wells Turbine Performance by Means of End Plate,” Proceedings of the 16th International Offshore and Polar Engineering Conference, San Francisco, 28 May-2 June 2006, pp. 480-484.
 K. Kaneko, T. Setoguchi and M. Inoue, “Performance of Wells Turbine in Oscillating Flow,” Proceedings of the Current Practices and New Technology in Ocean Engineering, Vol. 2, American Society of Mechanical Engineers (ASME), New York, 1986, pp. 447-452.
 T. Setoguchi, K. Kaneko and M. Inoue, “Determine of Optimum Geometry of Wells Turbine Rotor for Wave Power Generator,” Proceedings of 3rd Symposium on Ocean Wave Utilz, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Tokyo, 1991, pp. 141-149. (in Japanese)
 H. Osawa, Y. Washio, T. Ogata, Y. Tsuritani and Y. Nagata, “The Offshore Floating Type Wave Power Device ‘Mighty Whale’ Open Sea Tests: Performance of the Prototype,” Proceedings of 12th International Offshore and Polar Engineering Conference, Kitakyushu, 25-31 May 2002, pp. 595-600.
 Wavegen, “Islay LIMPET Project Monitoring Final Report,” 2002. http://www.wavegen.co.uk/pdf/art.1707.pdf
 A. Sarmento, A. Brito-Melo and F. Neumann, “Results from Sea Trials in the OWC European Wave Energy Plant at Pico, Azores,” 2006.
 T. Setoguchi, M. Takao, Y. Kinoue, K. Kaneko, S. Santhakumar and M. Inoue, “Study on an Impulse Turbine for Wave Energy Conversion,” International Journal of Offshore and Polar Engineering, Vol. 10, No. 2, 2000, pp. 145-152.
 T. Setoguchi, S. Santhakumar, H. Maeda, M. Takao and K. Kaneko, “A Review of Impulse Turbine for Wave Energy Conversion,” Renewable Energy, Vol. 23, No. 2, 2001, pp. 261-292. doi:10.1016/S0960-1481(00)00175-0
 T. Setoguchi, M. Takao, S. Santhakumar and K. Kaneko, “Study of an Impulse Turbine for Wave Power Conversion: Effects of Reynolds Number and Hub-to-Tip Ratio on Performance,” Journal of Offshore Mechanics and Arctic Engineering, Vol. 126, No. 2, 2004, pp. 137-140.
 T. Setoguchi, K. Kaneko, H. Maeda, T. W. Kim and M. Inoue, “Impulse Turbine with Self-Pitch-Controlled Guide Vanes for Power Conversion: Performance of Mono-Vane Type,” International Journal of Offshore and Polar Engineering, Vol. 3, No. 1, 1993, pp. 73-78.
 M. Takao, T. Setoguchi, K. Kaneko, T. H. Kim, H. Maeda and M. Inoue, “Impulse Turbine for Wave Power Conversion with Air Flow Rectification System,” International Journal of Offshore and Polar Engineering, Vol. 12, No. 2, 2002, pp. 142-146.