水池型鱼道紊流结构对鱼类溯游行为影响的机理

With the fast development of economy and society, the issues on effects of engineering construction on ecological environment are more and more concerned. There are abundant migratory fish species in coastal and riverine areas of China. Fishways can enable fish species to pass through obstructions for spawning, feeding and overwintering migrations. An efficiency of fishway is not only related to hydraulic characteristics in pools, but also depends upon behaviour of fish swimming. Fishways that fish could pass are less than half of built fishways in the globe! So it is of important realistic significance to further study hydraulic characteristics in fishways based on behaviour of fish species..This proposal experimentally investigates turbulent structures in single and combined fishways by means of 3D-PIV and 3D-ADV techniques, including three-dimensional velocity distributions, three-dimensional multiple turbulent jets, vortex characteristics, turbulence intensity, Reynolds stress, turbulence scales, velocity correlations and turbulent energy spectrums, and develops characteristics of turbulent structures in pool-type fishways. Also, it uncovers mechanisms of effects of turbulent structures in single and combined fishways on behaviours of fish swimming through fish test by the visible implant elastomer technique and high speed photography, of which various typical migratory fish will be selected as target species.

研究意义：随着经济社会的快速发展，工程建设对生态环境的影响问题越来越引起人们的关注。我国沿海、沿江鱼类资源丰富，洄游性鱼类众多，鱼道可使鱼类克服障碍物实现产卵洄游、索饵洄游和越冬洄游等。鱼道的过鱼效果不仅与鱼道池室的水力特性有关，而且还取决于鱼类的溯游习性。在全球已建成的鱼道中，鱼类能够溯游通过的鱼道尚不足一半！因此，进一步研究基于鱼类溯游习性的鱼道水力特性，具有重要的现实意义。.研究内容：利用三维PIV、三维ADV技术，试验研究单一式和组合式鱼道的紊流结构，包括三维流速分布、三维多股紊动射流、旋涡特性、紊动强度、雷诺应力、紊动尺度、流速相关系数、紊流能谱等，提出水池型鱼道紊流结构的特征；利用在鱼体植入荧光标记VIE和高速摄影技术，选择多种典型的洄游鱼类作为过鱼对象，通过放鱼试验，揭示单一式和组合式鱼道的紊流结构对鱼类溯游行为影响的机理。

我国沿海、沿江洄游性鱼类众多，通常在水闸、中低水头大坝等水利枢纽中设置鱼道使鱼类克服障碍物实现产卵洄游。鱼道的过鱼效果不仅与鱼道的水力特性有关，而且还取决于鱼类的溯游习性。本项目试验研究在大型鱼道水槽中进行，试验流量为20.62~61.8 L/s，利用声学多普勒测速仪（ADV）试验研究了平顶和凹口堰流式鱼道、矩形和卵形孔口式鱼道、同侧和异侧竖缝式鱼道、溢流堰与孔口组合式鱼道、溢流堰与竖缝组合式鱼道、孔口与竖缝组合式鱼道、溢流堰-孔口-竖缝组合式鱼道中三维流速、旋涡特性、紊动强度、雷诺应力、紊动尺度、流速相关函数、紊流能谱等紊流结构。竖缝式鱼道具有壁面射流的特征，水池内存在水平旋涡。堰流在水池内呈滑移流，并存在垂向旋涡，雷诺应力变幅在表层最大；卵形孔口的最大纵向流速沿程衰减比矩形孔口快，纵向流速和紊动强度呈马鞍形分布，孔口区涡旋尺度变化较大；溢流堰与竖缝组合式鱼道水流受凹口堰跌落射流和竖缝壁面射流的共同影响，堰流区存在较大尺度的涡旋结构，而竖缝壁面射流区的涡旋尺度则较小；凹口堰与孔口组合式鱼道的表层主频在堰流区，中层则在孔口射流区，涡旋之间的相关性低；凹口堰-矩形中孔-竖缝组合式鱼道的紊流能谱主频峰值大小为：孔口＞凹口堰＞竖缝；紊动尺度显示涡旋结构与组合式鱼道的流区有关。以鲫鱼、草鱼、鲢鱼、鳙鱼、鲤鱼、鲥鱼等为过鱼对象，体长为12.8~47.3 cm，在鱼体植入T形荧光标签，利用高速摄影机观察了过鱼对象的溯游行为，过鱼对象对即刻和即将溯游环境的选择与紊流结构相关，雷诺应力的变化是过鱼对象获得感应的关键区域，过鱼对象喜爱在紊动强度峰值区和雷诺应力较大变幅区溯游，而在其谷值区则徘徊打转。同侧布置的竖缝前后贯通，鱼类经常会被水流冲退，而异侧布置的竖缝交错排列，更适宜于鱼类上溯。中、底孔更适宜于喜爱在中、下层溯游的鱼类。过鱼对象溯游轨迹与旋涡特性有关。上述研究结果可为优化鱼道设计、修复鱼类生境，提供理论依据和技术支撑。