双侧竖缝式鱼道水力特性研究

研究分析不同水池长宽比条件下双侧竖缝式鱼道的水池流场结构及其水力学指标,为双侧竖缝式鱼道布置参数的优化选择提供技术依据。基于单侧竖缝式鱼道体型参数的研究成果,选取导板长度与水池宽度之比为0.25、竖缝宽度与水池宽度之比为0.15、导向角度为45°作为研究的基本体型;鱼道来流边界设置为压力进口,上游水深设置为2 m,出流边界设置为压力出口,下游水深设置为2 m;模型顶部设置为压力进口,进口压强为1.01×105Pa,边墙设置为固壁边界。采用三维数值模拟的方法研究分析了水池长宽比分别为4∶8、5∶8、5.5∶8、5.75∶8、6∶8、6.5∶8、7∶8、8∶8、9∶8的条件下双侧竖缝式鱼道的水池流场结构及其水力学指标。在不同水池长宽比条件下,鱼道常规水池内存在3种典型流场结构,其主流轨迹线、主流流速沿程衰减规律以及回流区分布等水力学指标均有不同,典型长宽比取值区间分别为4∶8~5.5∶8、5.75∶8~6.5∶8及7∶8~9∶8;对比发现,长宽比在5.75∶8~6.5∶8区间范围时,主流区宽度相对较大,水池空间利用较为充分,沿程流速衰减情况也较好,回流区主要分布于主流两侧且大小适中。初步认为长宽比5.75∶8~6.5∶8的水池流场结构较为合理。

Hydraulic Characteristics and Flow Structure in A Double Vertical Slot Fishway

The double vertical slot fishway, one of the basic types of vertical slot fishways, provides for double sided migration and is appropriate for large numbers of migrating fish. However, research on double vertical slot fishways has rarely been reported in China. In this study, a three dimensional numerical simulation model was used to investigate the flow structure and hydraulic parameters of the double vertical slot fishway with various pool-aspect ratios (the ratio of fishway length to width). The results provide a technical reference for the design of double vertical slot fishways. Based on previous research on single vertical slot fishways, several basic parameters for the double vertical slot fishway model were selected: upstream lateral baffle slope, 45°; lateral baffle length, 0.25B and slot width, 0.15B; where B is pool width. In the numerical model, the inflow and outflow boundaries were both set at a hydrostatic pressure of 2 meters, the top boundary was set at atmospheric pressure (1.01×105Pa) and all other boundaries were set as walls. The flow structure and hydraulic parameters of the general pools were then calculated using different length-to-width ratios (4:8, 5:8, 5.5:8, 5.75:8, 6:8, 6.5:8, 7:8, 8:8, 9:8). Results show that there are three typical flow structures in the pool, with different mainstream curves, velocity attenuation curves and recirculation area sizes. The three typical flow structures correspond to three ranges of length-to-width ratio (4:8-5.5:8, 5.75:8-6.5:8, 7:8-9:8). With increasing length-to-width ratio, the length and attenuation rate of the mainstream increased, while the distance between the two mainstreams decreased. The recirculation zones between mainstreams decreased correspondingly and the size of the recirculation region outside the mainstreams increased. The flow structure most appropriate in the pools occurs at a length-to-width ratio in the range 5.75-6.5:8. When the width of the mainstreams is relatively wide, the pools can be more fully utilized because mainstream velocity drops off rapidly and recirculation zones form that help fish pass successfully.