气垫驳船型浮式风机平台及其水动力性能研究

The next large-scale exploitation of wind energy will gradually move to the seas with depths of 30-100m. But there is no conclusion so far about what kind of wind turbines is better to be employed in the seas with such water depths. Although the fixed-bottom wind turbine can work in waters with depths up to 50m, the cost of installation and maintenance will be high. Obviously the use of fixed-bottom wind turbine in more than 50m deep areas requires unacceptable costs. In contrast, the floating wind turbine can be assembled in the factory and towed to wind field and installation on site can be very easy and quick, or inversely can be towed back from wind field to the factory for maintenance. Therefore, the floating wind turbine is more competitive even at the 30-50m deep seas, let alone at deeper seas..Among the exiting floating wind turbines proposed, only the semi-submergible and barge (pontoon) type platforms are suitable for seas with depths of 30-100m. Compared with semi-submergible platforms, barge type platform has simpler structure and is more adaptable to different water depths, however, suffers larger seakeeping motions in waves. In order to improve the seakeeping performance of the barge platforms for offshore wind turbines, the present work proposes a concept that integrating air cushion surrounded by side walls into the bottom of the platform to reduce wave loads acting on the platforms and therefore their motions. Nonetheless, the involvement of air cushion makes a system of coupling between wave, air cushion, platform/turbine and mooring lines, and the existing numerical methods are unable to analyze and compute the wave loads and motion response of such a system. The key parts of this project are: ① to design an optimal air cushion supported barge platform for floating wind turbines; and ② to develop a numerical method for predicting the wave loads on and responses of the structures that involves solving the complex wave-air cushion-platform/turbine- mooring lines coupling system. The outcome of the project will lay a firm technical foundation for harnessing the wind energy in the seas of depth 30-100m.

海上风能的下一步大规模开发将转向30-100米水深海域。在这种海域用何种形式的风机还没有定论。虽然在30-50米海域可用固定式风机，但其安装和维修成本较高；在50米以上海域用固定式风机成本将更高。而浮式风机可以在厂内整体装配好后拖航到风场，也可以拖回维修，因而在30-50米的海域也有竞争力，更不用说在更深海域。在现有的海上浮式风机中，仅半潜型和驳船型风机可用于30-100米海域。与半潜型相比，驳船型结构更简单，水深适应性更强。不过，驳船型风机在波浪中的运动较为剧烈。为克服其缺点，本项目提出了利用气垫减小其运动。然而引入气垫会产生波浪-气垫-平台-风机-锚链的耦合复杂系统，使得无法用现有的计算方法对其载荷、运动响应进行计算和预报。因而本项目的主要研究工作就是：①研发合适的气垫驳船型浮式风机；②发展可以求解波浪-气垫-平台-风机-锚链相互耦合的方法，为开发30-100米海域的风能奠定技术基础。

驳船型结构更简单，水深适应性更强，但其在波浪中的运动较为剧烈。为克服其缺点，本项目设计了气垫驳船型浮式风机系统。针对设计的气垫驳船型浮式风机系统，本项目对其稳性进行了详细研究，并与Star-CCM+数值模拟结果进行了对比，二者吻合较好。为研究该气垫驳船型浮式风机系统的耐波性，本项目发展了求解波浪-气垫-平台-风机-锚链相互耦合的方法，同时，本项目也使用Star-CCM+软件计算了气垫驳船型浮式风机系统的全系统耦合响应。此外，本项目对气垫驳船型浮式风机系统进行了试验研究，根据升力相似理论重新设计了试验模型叶片，并在风洞中试验了该叶片风机模型的推力和扭矩特性。在此基础上，本项目在波浪水池中对该气垫驳船型浮式风机系统进行了风浪耦合试验。本项目的研究可以为开发30-100米海域的风能奠定技术基础。