報告書番号

U03040

タイトル（和文）

ダブルＶＯＦ法による放水路内高濃度濁水進入現象の数値解析

タイトル（英文）

Numerical analysis for a high turbidity water flowing into a discharge tunnel of power plant using a double VOF(W-VOF) method

概要 （図表や脚注は「報告書全文」に掲載しております）

揚水発電所の下部貯水池に濁水が大量に流入すると、濁水の一部が高濃度化して下部貯水池の放水口から放水路内に進入し，発電所の運転に支障を来すことがある．この進入を予測し適切な対策を取るには，高濃度濁水進入現象のメカニズムを理解する必要がある．本報告書では，同現象を再現できる数値解析コードを開発して実験結果と比較することにより同現象のメカニズムを解明した．中部電力が実施した水理実験結果より，濁水が濁水-清水の密度界面を保持ながら進入する挙動が観察されたが，当所既開発の密度流解析コードＲＥＳＥＲＶ－３Ｄでは，この挙動を解析できなかったため，濁質の移動量を適正に算定し，界面を適切に追跡できる計算法（ダブルＶＯＦ法）を新たに開発した．ＲＥＳＥＲＶ－３ＤにダブルＶＯＦ法を導入した解析コードＲＥＳＥＲＶ－ＷＶＯＦを用いて，実験と同条件の解析した結果，濁水進入挙動および進入速度を精度よく再現できた．

概要 （英文）

When a large quantity of turbid water flows into a lower reservoir of a pumped storage power plant, one part of turbid water flows into the power plant's discharge tunnel filling with clear water.If high density turbid water reaches near to the power plant's generator in the tunnel, the generator cannot continue the operation.So, some electric power company investigates countermeasures to prevent such an approach. An adequate determination of the countermeasures requires accurate predictions of turbid water behavior in the tunnel. In this report, we developed a new computer code (RESERV-WVOF) for prediction of turbid water behavior in the tunnel.At first, we examine the results of hydraulic model experiment which was performed by Chubu electric power company.This result shows an density interface exists between turbid water and clear water while turbid water flows into the tunnel. Our three-dimensional numerical analysis code (RESERV-3D), which has been developed by CRIPEI, 2000 for prediction of water temperature and turbidity behavior in a reservoir, cannot simulate the interface behavior.So, to simulate such an interface, new analysis method (Double-VOF method) is developed.In this method, an interface between turbid water and clear water is treated like a water surface of VOF (Volume Of Fraction) method, and it is deformed by an advection current and a diffusion of suspended sediments contained in turbid water. The method can analyze both water surface and turbid-clear water interface.W-VOF introduced RESERV-3D (RESERV-WVOF) is applied to experiments. As a result, the velocity of turbid water and the computed behavior of the interface of turbid-clear water agree well with experimental results.So, it concluded that RESERV-WVOF is applicable to a prediction for the behavior of turbid water flowing into discharge tunnel.

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