報告書番号

N05052

タイトル（和文）

管路・開水路共存流れへの数値解析技術の適用

タイトル（英文）

Application of Numerical Simulation for Free-Surface-Pressurized Flows

概要 （図表や脚注は「報告書全文」に掲載しております）

発電所取放水設備や都市地下河川などでしばしば発生しうる管路・開水路共存流れを予測するため，３種類の数値解析コード，すなわち，スロットモデルを用いた１次元数値解析コード（コードＡ），スロットモデルと二流体モデルを用いた１次元気液二相流数値解析コード（コードＢ），CUPモデルを用いた鉛直２次元気液二相流数値解析コード（コードＣ）を開発した．開発したコードは，両端に立坑を有する管路における管路・開水路共存流れの過渡現象実験や満水管路への空気塊の浸入現象実験と比較・検討した．その結果，コードＡは管路内の空気が全て排気され，満水状態になる管路・開水路共存流れへの適用性は良いことが分かった．コードＢは管路内に空気が滞留するような状態にも適用できることが分かった．コードＣは管路・開水路共存流れの過渡現象や空気塊の浸入現象，ドライベッド上の流れなどへの適用性が良いことが分かった．

概要 （英文）

In this study, three numerical simulation codes are developed to analyze free-surface-pressurized flows, which are often observed in inlet tunnels, tailraces of power plants, underground flood ways, sewer networks, and so on. Their codes are 1-D code of horizontal liquid flows using slot model and implisit finete-difference schemes [CODE-A], 1-D code of horizontal gas-liquid two-phase flows using slot model and two-fluid model and implisit finete-difference schemes [CODE-B], and 2-D code of gas-liquid two phase flows using cup model and cip schemes [CODE-C]. Their CODE-A and CODE-B are compared with the experimental results of the unsteady flows, which include not only the open channel flows but also the pressurized pipe flow with entrapped air, in the horizontal pipe. It is clarified that CODE-B can evaluate the process of rising and falling water height in consideration of the entrapped air better than CODE-A. Also CODE-C is applied to the instusion process of an air cavity into a horizontal duct. The calculation results agree with the experimental process, and CODE-C can estimate the velocity and the pressure fields of liquid and gas flows well. Then three codes are applied to the unsteady free-surface pressurised flows in the duct, and their calculation results are compared. It is clarified that CODE-C of the process of water height, average velocity and gas displacement agree with CODE-B, and that CODE-C, using cip schemes, can calculate complex phenomena, such as flood on a dry bed, stabler than CODE-A and CODE-B, using implisit finete-difference schemes.

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