専 攻 名 システム工学 専 攻 氏 名

（様式

号） 「課程博士用」

学 位 論 文 の 要 旨

専 攻 名 システム工学 専 攻 氏 名

ふ り が な

李 慶 安 ○

学位論文題目

Study on flow field and aerodynamic forces of straight-bladed vertical axis wind turbine

英訳又は和訳 （ 直線翼垂直軸風車の流れと流体力に関する研究 ）

Compared with the Horizontal Axis Wind Turbine (HAWT), the simple design techniques of Vertical Axis Wind Turbine (VAWT) still have not been developed due to lack of the fundamental data. Especially, there are few research on analyzing the results of comparing the wind tunnel with field experiment. For the purpose of this study, the flow field and aerodynamic loading characteristics of straight-bladed VAWT are experimentally investigated by wind tunnel and field experiments.

In Chapter 1, firstly, the development backgrounds of wind power in the world and Japan are introduced. And then, classification of wind turbines and research status of VAWT are pointed out. Finally, research problems and significant objectives are discussed.

In Chapter 2, the main nomenclatures which are used for this research are shown.

In Chapter 3, the movement principle used for straight-bladed VAWT are described. In addition, some keywords (such as blade pitch angle, azimuth angle, attack angle , relative flow velocity W and so on) are also defined.

In Chapter 4, the measurement experiments are carried out in wind tunnel. In the process of introducing the experimental apparatus, the main experimental apparatus (such as wind tunnel, wind turbine, Laser Doppler Velocimeter (LDV) system, six-component balance, multiport pressure devices and so on) are presented. In order to clarify the characteristics of flow field around the wind turbine and aerodynamic forces acting on a blade of VAWT, the contents of measurement are explained.

Firstly, the torque meter which is installed in wind turbine axis of rotation can determine power and torque coefficients absorbed from a wind turbine. In flow field, the wind velocities are measured through LDV system at three different low tip speed ratios, under the condition that the blade number is from two to five. In order to explicate the characteristics of aerodynamic forces, the pressure distribution on the surface of rotor blade are measured during rotation by multiport pressure-scanner mounted on a hub, also the measured pressure signals are transmitted to stationary system through wireless LAN. And then, the six-component balance which is installed on the basement of wind turbine can measure the force and the moment applied to the entire wind turbine, in the x, y and z-axis directions.

続紙 有 無□

（様式

号－続紙） 「課程博士用」

氏 名

ふ り が な り けいあん

李 慶 安 ○

In Chapter 5, according to using multi-point pressure devices and LDV technologies in wind tunnel experiment, it is found that the tangential and normal force coefficients take maximum value when the blade is moving to upstream region and become smaller and smoother at downstream region. Moreover, the tangential and normal force coefficients decrease with the increase of blade number. The characteristic curves of the drag and lift coefficients against angle of attack form asymmetric hysteresis loops. Meanwhile, the maximum drag and lift coefficients are increasing with the increase of tip speed ratio. The power and torque absorbed from wind by a wind turbine mainly depends on upstream region. In addition, the values estimated from the pressure distribution are larger than value estimated from the torque measurements. Velocity vector has an asymmetry with respect to the x-axis. Furthermore, there is a low wind velocity region appeared from wind turbine internal region to downstream region. With increasing tip speed ratios, there is an expanding tendency of low wind velocity region. On the other hand, the reverse flow is generated at some regions of downstream.

In Chapter 6, the experimental apparatus and experimental methods in field experiment are explained. Field experiment of VAWT is carried out at Aoyama-highland, where the wind potential is high. The torque and rotor speed of VAWT are measured. The value of inflow and wake are measured through three cup-type anemometers and ultrasonic anemometers, and the wind direction is measured through wind vanes.

In Chapter 7, the experimental results estimated from the measured values are compared with field experiment and wind tunnel. The turbulence intensity in field experiment is much higher than the situation of wind tunnel experiment. According to comparing the results of power coefficient and wind velocity in the wake, it is much clarified that the power coefficient obtained by field experiment show larger value than the results of wind tunnel at low and high tip speed ratios. The wake velocity in field experiment enables a quicker recovery than the wake velocity in wind tunnel. Furthermore, with the increases of tip speed ratio, the wake velocity will be reduced in the scope of determination.

In conclusion, by comparison of the result of wind tunnel and field experiment, power performance, aerodynamic loading and flow field characteristics are obtained, achieving a numerical quantification of the effect of blade number at different tip speed ratios. It can be expected to establish a simple design techniques for the straight-bladed vertical axis wind turbine used in urban areas.

続紙 有□ 無