New Establishment of the Wave Energy Conversion System in the Ocean with Consideration to Environment and Economical Efficiency

振荡水柱(OWC)型波能转换系统由涡轮发电机和气室组成，气室将波的上下运动转化为振荡气流。威尔斯涡轮机是波能转换系统中最常用的空气涡轮机。本研究试图用流动显示和数值分析相结合的方法来分析这些三维绕流的机理。根据叶栅的势能理论，从理论上推导了涡轮的重要特性。威尔斯水轮机中安装了导叶，以提高其效率、自转特性。本文试图用动量理论来解释这些导叶的作用。介绍了一种分析带有OWC的浮子装置的二维数值方法。该方法求出了气室内无水表面和浮动装置底部满足边界条件的特解。根据与高效率不同的条件，即单位功率的最小尺寸等，剔除最优轮廓。在设计这种波能转换系统时，考虑相似律是非常重要的。由于实际应用，不仅精确相似律很重要，而且近似相似律也很重要，本文对此进行了描述。在设计中，在相同的输出功率下，浮动装置和涡轮的尺寸都很小，确保了启动性能。验证是通过将综合模拟技术与实际海试结果进行比较来进行的。如上所述，本研究通过实验和理论分析，明确了波能转换为电能过程中各元件的特性，确立了波能转换为电能的设计方法。

A wave energy conversion system of Oscillating Water Column (OWC) type is composed of a turbine-generator and an air chamber which changes up-and-down motion of a wave into oscillating airflow. A Wells turbine is the most commonly used air turbine for wave energy conversion systems. This study tries to analyze the mechanism of these three-dimensional flows around the turbine with the flow visualization and the numerical analysis. The important characteristics of the turbine are theoretically derived by the potential theory of cascade. Guide vanes are installed in the Wells turbine in order to improve its efficiency, self-rotating characteristics. This work attempts to explain the role of these guide vanes on the basis of momentum theory. The two dimensional numerical method for analyzing a floating device with an OWC is introduced. The method derives the particular solution that satisfies the boundary condition on the water free surface in the air chamber and on the bottom of the floating device. The optimal profiles are eliminated according to the different conditions from the high efficiency, i.e. the minimum size per a unit power and so on. That the similarity law is considered, when such wave energy conversion system is designed, is very important. It is not important only the exact similarity law, but also the approximate similarity law owing to practical use, and these are described in this paper. In the design, the size of the floating device and the turbine is made small under the same output, securing starting performance. Verification is performed by comparing the technique of a comprehensive simulation with the result of a real sea trial. As mentioned above, in this research, each element characteristic was clarified in the process of the conversion of wave energy into electrical energy through experiments and theoretical analysis, and the design method was established.