Prediction of the Total Dissolved Gas Downstream of Spillways Using a Two-Phase Flow Model

Politano, Marcela; Carrica, Pablo M.; Turan, Cagri; Weber, Larry

doi:10.1061/40737(2004)310

Cited by 7 publications

(2 citation statements)

References 11 publications

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“…However, application of the two-phase flow model has been limited by the lack of systematic research on the mechanism of bubble mass transfer and bubble size distribution. As such, further research is needed to improve the accuracy of the model (Politano et al, 2004). Mechanical models were proposed to predict the progression to TDG supersaturation on the basic theory of gas-liquid mass transfer and the process of gas-liquid flow over dam spillways.…”

Section: Introductionmentioning

confidence: 99%

Improved Model for Predicting Total Dissolved Gas Generation With the Residence Time of the Water in the Stilling Phase

Peng

Lin

Zeng

et al. 2022

Front. Environ. Sci.

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Quantitative predictions of total dissolved gas (TDG) super-saturation are essential for developing operation schemes for high dams. Most TDG generation prediction models have various shortcomings that affect the accuracy of TDG super-saturation estimation, such as oversimplification of influencing factors and uncertainty in parameter values. In this study, the TDG generation process was divided into three parts, gas-liquid mass transfer process in the stilling phase, dilution resulting from the water jet plunging into the stilling phase, and outflow of TDG–super-saturated water from the stilling phase, while considering the water body and bubbles in the stilling phase as a whole. The residence time of the water in the stilling phase (Tr) was introduced to estimate mass transfer time, along with dimensional analysis methods. The properties of TDG generation were evaluated experimentally under varying Tr values. Based on the theoretical analysis and experimental results, a basic water renewal model was proposed and was validated using experimental data. Furthermore, prediction results of this model were compared with those of a classical empirical model and mechanical model based on observed data from a field survey at Xiluodu Dam. The results show that the relative errors between the predicted and experimental measurements were all less than 5%, indicating that the developed prediction model has a good performance. Compared with the mechanism model, the developed model could reduce the standard error (SE), normalized mean error (NME), and error of maximum (REMAX) by 60, 96, and 15%, respectively. Meanwhile, the developed model could reduce the SE, NME, REMAX by 17.4, 36, and 23%, respectively, compared with the empirical model. Considering all the error indexes, it can be concluded that the prediction performance of the water renewal model is the best among the three models. The proposed model was also more generically versatile than the existing models. Prediction results of water regeneration model for TDG could aid the drafting of governing strategies to minimize the risk of super-saturated TDG.

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Section: Introductionmentioning

confidence: 99%

Improved Model for Predicting Total Dissolved Gas Generation With the Residence Time of the Water in the Stilling Phase

Peng

Lin

Zeng

et al. 2022

Front. Environ. Sci.

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“…More recently, Urban et al [31] added turbulent kinetic energy, flow rate, gas volume fraction, bubble size, and rise velocity with spatial dependency to a spillway TDG model. Politano et al [32][33][34] carried out a study of TDG supersaturation on the Columbia River, Washington with a two-phase model to predict the water entrainment from the powerhouse to the spillway using variable bubble sizes that changed due to dissolution and pressure. A key limitation of prior work (for present purposes) is the rigid free-slip approximation used for the water surface, which cannot be reasonably applied in the plunging pool of a high-head dam.…”

Section: Introductionmentioning

confidence: 99%

Two‐phase flow simulation of supersaturated total dissolved gas in the plunge pool of a high dam

Zhang

et al. 2016

Env Prog and Sustain Energy

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Total dissolved gas (TDG) supersaturation can cause potentially fatal Gas Bubble Disease (GBD) in fish and is recognized for its severe environmental impact for high‐dam operation conditions. The generation of supersaturated TDG in high‐head hydropower project is substantially different from middle‐ or low‐head projects that have been previously studied. Although the mechanics of TDG generation in a plunge pool are clearly three‐dimensional (3D), there are great challenges and difficulties of the 3D simulation for high‐dam projects. Toward this end, a two‐dimensional (2D) model of two‐phase flow in high‐dam plunge pool is developed with established computational fluid dynamics (CFD) software. New simulation modules are developed to account for a normal distribution of bubble sizes, which allows the TDG mass transfer from bubbles and across the free surface to include bubble size nonlinearities that were previously neglected. The model is calibrated based on observations from a high‐dam hydropower project with a ski‐jump spillway and deep plunge pool. Characteristics of simulated hydrodynamics, air‐bubble distribution, and TDG distribution downstream of the high dam were analyzed. Results showed that the model achieved satisfactory calibrated simulation of dissolved gas behavior and the assumption of a bubble normal distribution could properly reflect the bubble transfer process. Residence time in the plunge pool appeared to be a key factor determining maximum modeled TDG supersaturation levels. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1139–1148, 2016

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Multidimensional Simulation of the Two-Phase Flow Downstream of Spillways for Total Dissolved Gas Prediction

Politano

Carrica

Turan

et al. 2005

Impacts of Global Climate Change

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Prediction of the Total Dissolved Gas Downstream of Spillways Using a Two-Phase Flow Model

Cited by 7 publications

References 11 publications

Improved Model for Predicting Total Dissolved Gas Generation With the Residence Time of the Water in the Stilling Phase

Improved Model for Predicting Total Dissolved Gas Generation With the Residence Time of the Water in the Stilling Phase

Two‐phase flow simulation of supersaturated total dissolved gas in the plunge pool of a high dam

Multidimensional Simulation of the Two-Phase Flow Downstream of Spillways for Total Dissolved Gas Prediction

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