竖缝式鱼道90°转弯段水力特性的数值模拟

受枢纽布置与地形地质条件影响,竖缝式鱼道穿越公路、桥梁等建筑物或实现大转弯时通常需要布置90°转弯段。根据导板的布置位置,90°转弯段分为内内型、内外型、外内型与外外型4种类型。采用数值模拟技术计算4种类型90°转弯段的水流流场,主流区水流均紧贴边墙流动,主流区两侧出现尺度过大的回流区。针对出现的不利流态,提出了以增设整流导板的方式调整水流结构,并对水流结构改进后的水力特性进行了对比研究。增设整流导板后,主流区大致居中,主流衰减效果显著;回流区尺度合理,回流流速甚小。内外型90°转弯段增设一整流导板后,yi/B值介于0.30~0.71,说明主流区主要位于转弯段中间40%区域内;主流区两侧主要分布着3个回流区,位于弯段与弯段下游回流区的尺度最大,影响域为常规水池面积的0.9倍,长宽比为3.25,说明大尺度回流区的影响域为椭圆形区域,可便于鱼类游入与游出;弯段与弯段下游回流区内,靠近边墙的最大流速不超过竖缝断面平均流速的0.23倍,中心流速甚小,有利于鱼类良好休憩。内外型90°转弯段水流结构改进效果较其他3种类型更为明显,在实际工程中可考虑优先采用。

Numerical Simulation of Flow in the 90°Turn of a Vertical Slot Fishway

A 90° turning pool needs to be set where a vertical slot fishway passes through roads, bridges and so on, or makes a big curve influenced by the topographic and geological conditions. It is divided into in-in, in-out, out-in, out-out four types according to the central baffle position. The flow in the four types of 90° turning pools is studied by a numerical simulation method, and the results show that the mainstream flows close to sidewalls, and a big size reflux area appears on both sides of the mainstream. Above poor flow pattern is adjusted by setting rectifier plate, and the hydraulic characteristics of flow structure are studied. The results show that the mainstream zone is in the middle of the 90° turning pool, and the velocity attenuation is significant after adding rectifier plate. The size of reflux areas is reasonable, and velocities in reflux areas are small. The improvement effect of the flow structure in an in-out 90° turning pool is better than other types.