潮流能是一种典型的可再生能源，它是由于潮汐涨落引起海水水平方向流动而带来的能量。潮流能的能量密度高、工程建设简便、对环境影响很小，在我国东部沿海潮流速度较高的地区具有很高的开发价值。潮流能水轮机是将潮流能转化为转轮机械能，驱动发电机产生电能的关键装置。本文针对一种典型的升力型潮流能水轮机的核心工作部件—直叶片垂直轴式转轮，通过模型试验、数值模拟等手段对其水动力学特性进行了系统研究，为垂直轴式潮流能水轮机的工程应用奠定基础。采用牛顿力学及流体力学的基本方法，对垂直轴潮流能水轮机转轮在流场中运动与受力的非定常过程进行了分析，得出了垂直轴转轮在流场中运动的固有瞬态特性。基于将垂直轴转轮的运动简化为刚体绕定轴转动问题的思路，给出了垂直轴转轮运动与受力关系的基本方程。提出了一种耦合求解刚体动力学方程和流体运动方程的计算方法，通过引入六自由度模块来实现垂直轴转轮非定常运行过程的数值模拟。搭建了垂直轴潮流能水轮机循环水洞试验台，分别测试了两种叶片数的直叶片垂直轴模型转轮的水动力学性能。应用数值模拟方法对试验模型转轮进行了三维非定常数值模拟，通过与试验结果的对比验证了该模拟方法的可行性与准确性，并通过数值模拟获得了较宽尖速比运行范围的转轮性能。对比了不同工况条件下转轮受力及运动的瞬态特性，结合压力、流速等流场参数分析了转轮叶片处于不同方位角时转轮动力学特性的变化情况。选取了三种典型密实度、十组不同转轮几何设计参数组合的垂直轴潮流能水轮机转轮，通过数值模拟方法得到了各转轮在不同工况条件下的流体动力特性及流场分布。基于数值模拟结果，对比分析了叶片数、叶片翼型弦长及转轮直径等参数对转轮水力性能的影响规律，并给出了转轮设计中重要几何参数的选择原则。
Tidal current is a typical kind of renewable energy, which is caused by the horizontal flow of the sea water when tiding. The energy density of the tidal current energy is proportional to the cube of the flow velocity. It has high value for development in China eastern coastal areas where the flow velocity of the tidal current is quite high. The tidal current hydro turbine is a device which absorbs the kinetic energy of the tidal current, converts hydropower into rotation of the turbine runner, and driving the generator. In this paper, the research on transient characteristics of the straight blade vertical axis rotor, which is the key part of a typical lift type tidal current turbine, is conducted by model tests and numerical simulation. The research lays the foundation for further optimization design of the vertical axis tidal current turbine.Based on the basic theory of fluid dynamics and fluid machinery, the unsteady process for the motion and force of the vertical axis rotor in the flow field is analyzed. It is found that the transient characteristic of the vertical axis rotor is inherent. The motion of the rotor is simplified as a rigid body rotating about a fixed axis. The basic equation for the motion and force of the vertical axis rotor is given. By solving the rigid body dynamics equations to get the state of rigid body motion, and by computational fluid dynamics to get the force information, a method coupling these two steps by iteration is suggested. A numerical simulation method which couples the 6DOF module and computational fluid dynamics is introduced, and the simulation flow chart for the unsteady running process of the vertical axis rotor is described in detail.A cycle water tunnel test bed for vertical axis tidal current turbine is established, and the model rotors of a straight blade vertical axis rotor for two kinds of blade number are tested. The 3D unsteady numerical simulations of the model rotors are conducted. The results comparison of test and simulation show the feasibility and accuracy of the numerical methods. The simulation can get a wider working tip-speed ratio range for the rotor. Based on the simulation results, the transient characteristics and flow field distribution are analyzed.By the numerical method which couples the 6DOF module and CFD, ten different vertical axis rotors for three kinds of typical solidity which have different geometry parameters are simulated. The comparison of the power characteristics and the flow field for the rotors show the changing rule how the different geometry parameters affect the rotor performance, and the rule of determining parameters were discussed.
