莲花寺水电站表底孔联合消力池水力研究

Hydraulic study of combined stilling basin between overflowing orifice and bottom outlet in Lianhuasi Hydropower Station

莲花寺电站最大坝高仅有29 m、溢流堰前后最小水位差仅有9.54 m,属于典型低水头闸坝工程,这类工程往往具有低佛氏数、下游深尾水以及消力池内消能紊动不足等特点.通过物理模型试验针对莲花寺电站原底孔折线型消力池内消能紊动不充分、淹没水跃滞后、出池水流过大等问题,提出拆除消力池内纵向隔墩、形成表底孔联合消力池,得出以下结论:表底孔联合消力池借助消力池横向宽度,利用表孔、底孔入池水流纵向流速梯度、横向能量差,加剧消力池内横向水流扩散,增强水流碰撞耗散,提升消能效果.尤其是单独开启表孔、底孔泄洪时,入池水流显著向两侧扩散、偏移,形成三元水跃,有效增强消力池上游区域紊动耗散,减小出池水流流速,能为类似闸坝工程提供参考作用.

With maximum dam height up to 29 m and water level drop down to 9.98 m downstream the overflow weir, Lianhuasi Hydropower Station belongs to the typical low head projects, which are often faced with deep tailwater or insufficient energy dissipation inside stilling basin. Based on physical model, this paper detailedly studies the serious problems of large outflow velocity, hydraulic jump downstream stilling basin as well as insufficient turbulence in original design of Lotus Temple Hydropower Station, and proposes combined stilling basin between surface hole and bottom hole to aggravate longitudinal velocity gradients and compel rushing inflow to laterally diffuse or collide to increase shear turbulence and collision upstream the stilling basin, which is especially observable in solely opening surface hole gate or bottom hole gate, 3 dimensional hydraulic jump upstream stilling basin obviously intensifies lateral diffusion, improves flow pattern inside stilling basin, and slows down outflow velocity.