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Newsletter  2012.12  Index

Theme : "Fluid Machinery in Industry"  

  1. Preface
    (K. Kobayashi, H. Yoshikawa, Y. Sekino)
  2. Studies on suction performance improvement and cavitation instabilities in turbo-pumps
    Satoshi WATANABE (Kyushu University)
  3. Oscillating Water Column Type Wave Power Generating System
    Masami SUZUKI (University of the Ryukyus)
  4. Development of Environmentally-Friendly Waterjetting Technologies for Energy Resources
    Akihisa KIZAKI (Tohoku University)
  5. Innovative Design and Manufacture of Process Gas Centrifugal Compressors
  6. Investigation of the root cause phenomena in the pump by using the flow visualization technologies - Hybrid method of experiment and CFD -
    Masahiro MIYABE (Torishima Pump Mfg. Co., Ltd.)

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Oscillating Water Column Type Wave Power Generating System

Masami SUZUKI,
University of the Ryukyus


A wave power generating system is classified broadly into a moving body type, an overtopping wave type, and an oscillating water column (OWC) type. The moving body type is a system which changes the motion of floating body into energy. There are the systems using the pitching and rolling motion, the oscillation of pendulum, and a point absorber which drives a piston or a linear motor installed in the seabed. Moreover, there is also a system which changes the rolling motion of floating body into torque with a gyroscope. The overtopping wave type is a system in which the hydro turbine is driven by the low head sea water in the reservoir on the land or the ocean that stores the overtopping wave water. An oscillating water column type is a system in which an air turbine is arranged at the upper part of the air chamber installed on the water surface, and a turbine is driven by the oscillating air flow which is produced by the motion of the water surface in the air chamber (OWC) excited by the up-and-down motion of a water wave. The Wells turbine and the impulse turbine are mainly used for the oscillating air flow. On the other hand, the early system also installed a usual turbine which is driven by the unidirectional flow into which the rectification valve changes the oscillating flow. The optimum system of the oscillating water column type wave power generation is designed by coupling the characteristics between the air chamber and the turbine.

Key Words

Renewable energy, Wave power generation, Oscillating water column, Wells turbine, Impulse turbine


Fig.1 Wells turbine with guide vanes


Fig.2 Characteristics of a floating type wave power generation with OWC: the amplitude of pressure in the air-chamber, p, the efficiency of OWC, ηOWC, the amplitude of refection wave, αr, and the amplitude of transmitted wave, αt.

Last update: 12.14.2012