消力池内悬栅消能工的消能机理及栅条最优布置方法研究

The energy dissipation by suspension grids have the characteristics such as higher energy dissipation rate, good effect of steady flow and small environmental impacts and so on. Drawing lessons from the energy dissipation research by the suspension grids at the steep slope rapids corner in previous stage, aimed at the difficulty of the energy dissipation at the export of the bottom hole stilling basin of the Wuyi Reservoir and Xiao Shixia Hydropower Station in Xinjiang, the research group put forward to set up the suspension grids in the stilling basin for the first time and successful implementation. However, research on the hydraulic characteristics, the energy dissipation rule, the position, shape and how to determine the number of the suspension grid still be at the initial stage, especially for the mechanism research about the energy dissipation by the suspension grids in stilling basin was rarely reported. This project will take the energy dissipation by the suspension grids in stilling basin for the research object, using the PIV velocity measuring technology and FLUENT fluid simulation technology, through the theory analysis, model test and numerial simulation method combining the prototype observation, major research the hydraulic characteristics by adding the suspension grids in the still basin, the energy decline rule and the layout method for the suspension grids, expound the mechanism of energy dissipation by the suspension grids in the bottom flow stilling basin, reveal. the effect regular by the parameters as the different location of the suspension grid, shape and numbers to the energy dissipation rate and steady flow, establish the calculation method for optimal layout scheme of the suspension grids in the stilling basin. These can provide the theoretical basis for designing the similar project of the bottom flow stilling basin.

悬栅消能工具有消能率较高、消波效果好、环境影响小等特点，借鉴前期陡坡急流弯道悬栅消能研究，针对新疆五一水库和小石峡水电站底孔泄洪兼排沙洞出口消力池消能难题，课题组首次提出在消力池内设置悬栅消能工并成功实施，但关于消力池内设置悬栅消能工的水力特性、能量耗散规律和悬栅位置、体型、数量如何确定的研究尚处于起步阶段，尤其对消力池内部悬栅消能机理研究鲜有报道。本项目以底流消力池内设置的悬栅消能工为研究对象，采用PIV流速测量技术和FLUENT流体模拟技术，通过理论分析、模型试验和数值模拟方法并结合原型工程观测，重点研究消力池内加设悬栅后的水力特性、水流能量耗散衰减规律以及高消能率时悬栅布置方法，阐明悬栅在底流消力池内部的消能机理，揭示悬栅不同位置、体型、数量等参数对消能率和消波特性的影响规律，建立消力池内悬栅最优布置方案的计算方法，为类似底流消力池工程设计提供理论依据。

悬栅消能工具有消能率较高、消波效果好、环境影响小等特点，针对新疆五一水库和小石峡水电站底孔泄洪兼排沙洞出口消力池消能难题，课题组首次提出在消力池内设置悬栅消能工并成功实施。项目以底流消力池内设置的悬栅消能工为研究对象，采用PIV流速测量技术和FLUENT流体模拟技术，运用投影寻踪回归PPR对试验数据进行建模仿真，通过理论分析、模型试验和数值模拟方法并结合原型工程观测，得到以下结论：（1）池内加入悬栅后水跃明显前移，水流受到悬栅迎水面阻挡、撞击、剪切后分为两股水流，在消力池内形成绕栅环流，水跃漩滚区呈现水汽两相掺混流态，形成数量众多小涡体，并经过与悬栅碰撞、摩擦、剪切和混掺等，消耗大量入池水体动能，下游流速降低，池内水流平稳，悬栅的置入对于消力池稳流和消能效果明显。（2）消力池内悬栅消能工最优体型为矩形，为了避免入池高速水流产生飞溅，可在消力池涡奇段设置楔形悬栅。悬栅最佳间距应不小于一个漩涡的长度。（3）单层悬栅选取栅条数量ns、栅高hs、栅距bs三因子作为消能效果影响因子，运用均匀正交进行试验设计，借助PPR建模仿真得到池内最大水深影响因子排序为ns>bs>hs。设消力池宽度B，栅高hs=0.58B～0.65B，栅距bs=0.2B～0.25B，栅条数量ns取16～20根最优，在此区间取值消能效果较优。（4）采用量纲分析法推导出单层悬栅栅高公式，利用Origion软件对试验数据进行多元线性函数拟合，得到悬栅高度的计算经验公式。（5）对双层悬栅进行均匀正交设计试验，当双层悬栅层距、栅距、栅条数与池深的比值为0.4、1.2、1.1时，消力池内水流稳定，消能效果理想。.课题重点研究了消力池内加设悬栅后的水力特性和水流能量耗散衰减规律，阐明了悬栅在底流消力池内部的消能机理，揭示了悬栅不同位置、体型、数量等参数对消能率和消波特性的影响规律，建立了消力池内悬栅最优布置方案的计算方法，为类似底流消力池工程设计提供理论依据。