Kyushu University
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  • Offer Profile
  • Welcome to Wind Engineering Section at Kyushu University research institute for applied mechanics (RIAM). Our research interests include, problems of fluid dynamics related to wind environments such as airflow over complex terrain and urban canopy, effect of wind forces on buildings and structures, and wind energy as clean and renewable energy. As a part of the research on renewable energy source, we have developed a new wind turbine technology called "Wind Lens". Development of the wind-lens turbine has recently entered new stage which consists of two main components. They are augmentation of wind lens application to mid to large size wind turbine and utilization of the wind-lens turbines as a core part of future off-shore energy farm.
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  • Research

  • Wind Engineering Section attacks problems related to turbulence of the atmospheric boundary layer, prediction of wind systems over local topography, aerodynamic characteristics of bluff bodies, also development of new wind turbine system, and computational fluid dynamics in wind engineering. As our tools for the research, we utilize various wind engineering facilities including boundary-layer wind tunnel,thermally stratified wind tunnel and water tanks.
  • "Wind Lens"

  • Wind power is proportional to the wind speed cubed. If we can increase the wind speed with some mechanism by utilizing the fluid dynamic nature around a structure, namely if we can capture and concentrate the wind energy locally, the output power of a wind turbine can be increased substantially. At wind energy section of Kyushu University, a new efficient wind power turbine system has been developed. This system has an diffuser shroud at the circumference of its rotor to embody the wind energy concentration. The diffuser shroud is now named "Wind lens". To apply the wind-lens structure to a larger size turbine, we have developed a compact collection-acceleration device. There are several ongoing projects in which the wind-lens turbines are involved.
    • Development of wind energy and new wind turbine system

    • To contribute to increase the share of clean renewable energy sources, we have been developing a new effective wind power concentration system. This technology is named "Wind Lens". The Wind Lens can improve output power of wind turbine by a factor of 2 to 3 compared to conventional wind turbine that has the same rotor radius. This research is also a part of new generation of off-shore power plant.
    • How does the Wind Lens work?

    • Strong vortices created by the diffuser and the brim of the Wind Lens produce low pressure region behind the turbine. This increased pressure difference that helps the wind to flow more into the Wind Lens.
  • Next stage of the development of Wind Lens

  • Since wind load on the Wind-Lens turbine is larger than typical wind turbines, application of the Wind Lens to turbines in larger size faces structural challenge. As a part of development of next generation Wind-Lens turbines, two mid-size (100 kW with wind speed 12m/s) wind-lens turbines have been currently constructed at Ito campus of Kyushu University. This version of the turbine has much larger structural dimensions than our 5kW turbines. The 100 kW turbine has a rotor which spans 12.8 m in diameter, diffuser diameter 15.4m, and the whole structure reaches 34 m high above the ground. This project is an important mile stone toward an ongoing project of off-shore energy farm. The first stage of off-shore wind farm development has begun. A set of water tank experiments has been carried out recently as a preparation for near future construction of off-shore wind farm built on a floating structure on Hakata-bay (18m in float diameter, with a couple of 5kW Wind-Lens turbines). We are preparing for the construction possibly as early as Autumn 2011. This plan leads us to the second stage development of the wind farm, which consists of larger floating structure (60m in diameter, with a couple of 100kW Wind-Lens turbines). The planned location is Genkai-nada Sea, Fukuoka.
  • Hot research topics

    • Turbulence structure and transport characteristics of the atmospheric boundary layer

    • We are trying to find out characteristics of exchange and transport processes of momentum, heat and constituent occurring inside the turbulent atmospheric boundary layer. A large number of numerical simulations are carried out as much as physical simulations such as large wind tunnel experiment.
    • Aerodynamic characteristics and flutter phenomena of bluff bodies

    • Behavior of air flow around a body in non-streamlined shape (bluff body) placed in the atmospheric boundary layer is very interesting. We aim for establishing a general explanation for flow around the bluff bodies. Also, a body in a flow often vibrates. Sometimes the amplitude of the oscillation increases naturally and causes serious damages. This is called "flutter". We study about the mechanism and effective prevention of the flutter.
    • Prediction of wind systems over local topographic features (RIAM-COMPACT package)

    • We study air flow over and around buildings, minor landforms, also over complex terrain and urban canopy by using wind tunnel experiments and carrying out various field works to establish effective method of predicting micro and local wind conditions. Numerical approach which has been rapidly advancing in recent years in fluid dynamics is also one of our strong tools to attack the problems.
    • Exchange process of momentum, heat and constituent between the atmosphere and ocean

    • Refining meteorological method to determine amount of carbon dioxide exchanged between the atmosphere and ocean (including eddy correlation method, aerodynamic technique of gradient method, and bulk method) is also one of our research topics. At the same time, we are trying to find out relation between local climate and the amount of the exchanged carbon dioxide.