Savonius型水轮机群的仿鱼类群游态布局研究

Effective use of energy and the overall state of environment are essential for global sustainable development. Flowing water can rotates the blades in the turbine and thereby the kinetic energy in the water can be converted into mechanical power, which can then be transformed into electrical energy through electrical generator. Therefore, moving water is a clean and ever lasting source of energy that can be exploited for utilization. It is of great importance to develop high-efficiency low-cost water current kinetic energy converter such as horizontal or vertical axis turbines. In addition, water current turbines must also be installed in clusters called a turbine farm in order to generate as much electricity as a big nuclear or coal-fired power plant. Currently, most of water current turbines adopted are very similar to wind turbines and are generally spaced as far apart as possible in a farm in order to minimize the effect of mutual interference between turbines on their power output. However, the patterns that schooling fish form to save energy while swimming have inspired us to believe that beneficial interactions similar to the energy saving mechanism in fish school swimming may also exist among some types of water current turbines like Savonius type in a farm, which can help increase the power output of turbines instead of causing energy losses if these turbines can be placed close enough together and in the right position. Therefore, this application aims to explore the mutual coupling effects among multiple Savonius turbines, study the effect of parameters (separation distances and relative phase angles between the turbines) on their hydrodynamic characteristics, and analyze the relationships between these parameters and power output performance characteristics of Savonius turbines. Finally, a new approach imitating schools of fish could be developed for optimizing the large Savonius turbine farm layout.

能源与环境是当今社会的两大主题，水流的动能可以推动叶轮旋转，将动能转换为机械能，进而带动发电机而转换成电能。我国不少海域或江河中川流不息的水流是一种可开发利用的清洁能源，研究高效低成本的水流能利用装置对节能减排具有重大意义。目前研制中的水流能发电装置大多沿袭了传统风力发电机的设计方法，且通常认为，机群中每个机组单元应保持尽可能远的距离，产生的干扰越小越好。然而，鱼类群游中每条鱼可利用相互间的干扰来降低个体游动时的阻力、减小功耗的事实启示我们：合理利用水轮机群中各单元之间流场的相互干扰，有可能提高机群的水能利用率。本项申请将针对Savonius型水轮机机群，从流场结构和能量转换机理出发，探讨多个转子之间的相互耦合机制，研究转子间横向间距、流向间距以及相邻转子转动相位之间的关系对机群的流场结构、水动力学特性的影响，分析这些参数与水能利用率之间的关系，实现Savonius型水轮机群的优化布局。

潮流能是一种绿色可再生新能源，开发利用潜力巨大。本项目以Savonius型垂直轴水轮机为对象，研究多个水轮机转子之间的耦合效应，以及它们组成的机群获得最高能量转换效率的最优布局方式。单个Savonius型水轮机转子的效率较低，但当两个转子同时运转时，在一定条件下，它们之间的耦合效应可以显著提高两转子的做功效率。项目中对Savonius型水轮机转子间的流场进行了数值模拟研究，分析了在不同的旋转方式下，两个转子并列和斜向布置时它们流场间的耦合机理。数值模拟结果表明，Savonius型转子之间的间距和相位差对转子耦合运转时的水动力性能影响显著。在最优的布置方式下，两转子耦合运转时的功率较单独运转时可以提高37%左右。在对两个转子耦合流场分析的基础之上，研究了多个转子之间的耦合效应，提出了多个转子同时运转时较优的布局方式，并对其中十个转子和七个转子同时运转且仿鱼类群游态布局时的流场进行了数值模拟研究。结果表明在多个转子形成的机群中，它们之间的流场干扰对位于不同位置处转子的水动力性能影响不同，当下游转子的逆流段叶片位于上游转子的尾流区时，其能量转换效率可以有明显提高。机群中相邻转子间的间距对其能量转换效率影响显著，在较大间距下，下游转子受上游转子尾流的影响变小，整个机群的能量转换效率提高，在合适间距及旋转相位下，采用仿鱼类群游形态布局可以有效的利用相邻转子间有益的流场间相互干扰，从而提高具有这种结构形式的水轮机转子形成的机群整体的能量转换效率。项目中还利用风浪水槽对多个转子间的耦合效应进行了实验研究，验证了数值模拟结果中的部分结论。本项目的研究结果表明垂直轴式水轮机形成的机群中相邻转子间的间距可以很小，因而在水速大，且空间狭窄的水道中使用，与水平轴水轮机相比将具有明显优势。