半潜式多浮体波浪能发电装置的水动力性能分析

Hydrodynamic performance analysis of semi-submersible multibody wave power plant

为缓解能源危机及环境恶化,加大对可再生能源的开发利用,本文将点吸收式与筏式波浪能转换技术相结合,提出一种半潜式多浮体波浪能发电装置。该装置主要由中央漂浮平台、振荡浮子、液压系统及驱动臂组成,将多个振荡浮子布放于海面上并采集波浪能。为了提高装置的波浪能采集效率,利用AQWA水动力仿真软件对波浪能发电装置进行建模仿真分析,改变模型中浮子的质量、尺寸及结构等参数进行频域计算并分析单个浮子的频域响应;同时对单个浮子及装置整体在波高为1 m,波浪周期分别为5 s和3 s的海况下的时域响应特点进行分析。结果表明:浮子吃水部分的几何形状对于浮子附加质量及波浪激励力影响较大;同时当浮子的直径为2 m且浮子结构为圆柱形时,浮子的垂荡振幅更大,说明在波浪频率较低时更有利于最大限度地捕获波浪能,提升装置整体效率;而对于波浪频率较高海域,应当适当增加浮子直径,减轻浮子重量,采用圆锥形浮子,从而更有利于浮子捕获波浪能。采用最优浮子结构后,装置的波浪能捕获宽度比提升约95%,说明选用合适的浮子结构能够有效地提升装置的波浪能采集效率。

To alleviate energy crisis and environmental degradation and enhance the development and use of renewable energy,this study develops a numerical model of a semi-submersible multi-floating body wave power plant through combining wave energy conversion technologies of point absorption and raft type.The device is mainly composed of a central floating platform,an array of oscillating floats,a hydraulic system,and structure connecting floats to the platform,and collects wave energy from the oscillating floats on the sea surface.To improve its collecting efficiency,we numerically simulate and examine its energy conversion using AQWA hydrodynamic simulations,and analyze the frequency domain responses of a single float with different values of parameters such as the mass,size,and structure of the floats.And a detailed analysis is made on the time domain responses of a single float and the whole device under sea conditions of wave height of 1 m and wave periods of 5 s and 3 s.The results show that the geometry of the underwater part of the float has a great influence on its added mass and wave excitation force,and that a cylindrical float of 2 m in diameter features larger amplitude of vertical oscillations.This suggests that in the condition of low wave frequencies,the floats with such a design can capture wave energy closer to the maximum extent,thereby improving overall efficiency.For the floats working at high wave frequencies,they should have a conical shape,the diameter increased appropriately,and the weight reduced so as to capture more wave energy.By optimizing float structure,the energy collection efficiency of the device is raised by about 95%,indicating the importance of float structure in efficiency improvement.