Evaluation of operational strategies to minimize gas supersaturation downstream of a dam
Evaluation of operational strategies to minimize gas supersaturation downstream of a dam
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DOI：
10.1016/j.compfluid.2012.08.003
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发表时间：
2012-09-15
影响因子：
2.8
通讯作者：
Hay, D.
中科院分区：
文献类型：
--
作者：
Politano, M.;Amado, A. Arenas;Hay, D.
溢洪道下游的气泡溶解可能会产生高总溶解气体（TDG）浓度的区域，这可能对鱼类有害。本文介绍了使用数值模型来确定大坝运行策略，以减轻TDG产量的增加。混合模型考虑了气泡对流体力学的影响。该模型考虑了溶蚀和压力对气泡溶蚀大小的影响。利用现场速度和总井底数据对模型进行了验证。为了了解不同操作配置下导致过饱和水的物理现象，进行了多次模拟。根据该模型，将溢洪道的水流集中在一个海湾内，使气泡更接近自由表面，从而降低TDG产量，增加脱气。为了获得最低的总渗水浓度，最好将大部分流量集中在中央溢洪道湾内。如果需要溢出额外的水，建议使用西湾。另一个符合条件的模拟表明，采用建议的配置，大坝符合TDG水质标准。此外，对溢洪道和水轮机中释放的惰性颗粒进行统计分析表明，2 h后，83.9%的惰性颗粒暴露于TDG值低于110%的时间。如果考虑流体静力补偿，则颗粒在70%的时间内处于不饱和水中。(C) 2012 Elsevier Ltd.版权所有。
Bubble dissolution downstream of spillways may create zones of high total dissolved gas (TDG) concentration, which can be detrimental to fish. This paper presents the use of a numerical model to identify dam operational strategies that mitigate elevated TDG production. A mixture model takes into account the effect of the bubbles on the hydrodynamics. The model calculates bubble dissolution considering bubble size change due to dissolution and pressure. The model is validated using field velocity and TDG data.Several simulations are performed to understand the physical phenomena leading to supersaturated water under different operational configurations. According to the model, concentrating the spillway flow in one bay causes bubbles to travel closer to the free surface and thus lower TDG production and more degasification. In order to obtain the lowest TDG concentration, it is best to concentrate most of the flow in a central spillway bay. If additional water needs to be spilled, the use of a western bay is recommended. An additional simulation using compliance conditions indicates that, using the proposed configuration, the dam meets TDG water quality standards. Moreover, statistical analysis performed on inert particles released in the spillway and turbines demonstrates that, after 2 h, 83.9% of the time particles are exposed to TDG values lower than 110%. If hydrostatic compensation is considered, particles are in undersaturated water 70% of the time. (C) 2012 Elsevier Ltd. All rights reserved.