■Open Air Rotor Research

Wind turbines are operated in fluctuating natural winds. Therefore, the power output of the wind turbine fluctuates, and the fatigue load is acted on the wind turbine. In the open air rotor research, the wind speed and direction are measured by wind measuring devices installed around a wind turbine, and the power generation by the wind turbine and the load acting on the wind turbine are measured to determine the relationship between wind characteristics and wind turbine performance. Currently, we aim to realize predictive control which can detect the wind upwind of the wind turbine in advance by using ultrasonic anemometers and can optimize the operation of the wind turbine according to calculating the timing when the wind reaches the wind turbine.

■Flow Analysis around Horizontal Axis Wind Turbine

A wind turbine extracts energy from the wind and converts it into electricity. Therefore, in order to improve the efficiency of the wind turbine, it is necessary to investigate the relationship between the flow of wind passing through the wind turbine and the performance of the wind turbine. In the research of horizontal axis wind turbines, we are operating a scale-modeled wind turbine in a large wind tunnel to clarify aerodynamic phenomena. A laser Doppler anemometry is used to measure the flow around the wind turbine, a highspeed multiport pressure scanner is used to measure the pressure on the blade surface during rotation, and a six-component balance is used to measure the loads acting on the wind turbine. Through these measurements, we aim to clarify the aerodynamic phenomenon of wind turbines and develop highly efficient wind turbines.

■Performance and Load Analysis of Vertical Axis Wind Turbine

A vertical axis wind turbine that rotates around a vertical axis is attracting attention as an urban wind turbine because it can be operated regardless of the wind direction and has low noise. On the other hand, the aerodynamics of vertical axis wind turbines are complicated, so the design requirement has not been established. In the research of vertical axis wind turbines, the output power and the load of vertical axis wind turbine are analyzed by wind tunnel experiments, field experiments and numerical analysis. We aim to develop highly performance and reliable vertical axis wind turbines and to establish a design method vertical axis wind turbine.

■Analysis of Load and Flow acting on Airfoils

When a wind turbine extracts energy from the wind, the most important part is the blade. The airfoil cross-section of the wind turbine blade is streamlined, and its shape greatly affects the wind turbine performance. In airfoil research, we are investigating the development of airfoils suitable for wind turbines and changes in aerodynamic characteristics when natural roughness such as icing are attached to the blade using wind tunnel experiments and numerical analysis. Through these studies, we aim to improve the efficiency of wind turbines and construct optimal operation methods.

■Performance Evaluation of Wind Turbines in Wind Farm

In a wind farm where many wind turbines are arranged in a site, the wind that has passed through the wind turbines on the upwind side flows into the wind turbines on the downwind side. As a result, the output of the wind turbines on the downwind side decreases and the fatigue increases. In the wind farm research, we analyze the effect of the wake of the wind turbines on the power generation of the wind turbines on the downwind side. The relationship between terrain, where the wind turbines are installed, and the power generation of the wind turbines is also analyzed. We develop the optimum arrangement of the wind turbines in the wind farm and study the optimal operation control of the wind turbines in the wind farm.