侧式进/出水口及邻近围堰环流消除优化研究

抽水蓄能电站侧式进/出水口施工完成后，往往对其施工围堰采用不完全拆除方式，从而形成残留围堰。当水库运行水位较低时，进/出水口前方水面在残留围堰和地形的影响下，很可能出现不利环流现象。这种不利环流，在出流工况下易造成进/出水口前方水面波动较大，在进流工况下易诱导进/出水口上方形成有害漩涡。本文以潍坊抽水蓄能电站下水库侧式进/出水口为例，采用数值模拟方法，探寻改善围堰附近水流流态的有效措施。为消除围堰附近的环流，对围堰平台的坡底线进行优化，比较各体型优化效果并进行物理模型试验验证。研究表明：侧式进/出水口前存在残留围堰时，进流工况库区水面流态平稳，出流工况围堰附近容易形成不利环流；对称的残留围堰不会避免环流的产生；当残留围堰平台坡底线角度与明渠扩散角度保持一致，可以降低环流强度，水流可平顺均匀地向库区扩散，水流条件有较大改善。本文研究成果可为同类型抽水蓄能电站侧式进/出水口围堰设计提供参考。

Study of circulation elimination and optimization for side inlet/outlet and adjacent cofferdams

After the construction of the side inlet/outlet of a pumped storage power station is completed, usually the adjacent cofferdams cannot be dismantled completely, leaving the cofferdam residues in situ. At low operating water levels, adverse circulations are likely to form in the surface layer of water flows in front of the inlet/outlet under the influence of residual cofferdams and topography, and tend to cause large water surface fluctuations in outflow mode or induce harmful vortices above the inlet/outlet in inflow mode. This paper explores effective measures to improve flow patterns around a side inlet/outlet and cofferdam residues, using the computational fluid dynamics method in a case study of the Weifang pumped storage power station. To avoid the circulation, we modify and optimize the cofferdam slope and its bottom edge location, and compare and verify the effect of different schemes against the measurements on a physical model. The results show that when residual cofferdams exist in front of a side inlet/outlet, flow patterns at the water surface in the reservoir area are usually stable in inflow mode, but an adverse circulation is very likely to form around the cofferdams in outflow mode and it cannot be avoided by adopting a symmetrical design of the cofferdams. When the cofferdam’s slope bottom edge is along the direction of the diffusion flow in the open channel section, the flow spreads smoothly and evenly into the reservoir area, greatly improving the flow conditions.