報告書番号

U99021

タイトル（和文）

水平管内気液二相流における流動と圧力変動に及ぼす出口水位条件の影響

タイトル（英文）

Effects of Water Levels at the Outlet Section on Flow Patterns and Pressure Fluctuations in Horizontal Air-Water Two-Phase Flows

概要 （図表や脚注は「報告書全文」に掲載しております）

本研究では、管内径100mm、長さ19.5mの水平管を用いて、出口水位が管路底面よりも低い場合の気液二相流と、出口水位が管路天端よりも高いためにエアハンマー現象が発生しうる場合の気液二相流を対象とした実験を実施し、流動様式、流入流量変動、空気塊の挙動や大きさおよび管内圧力変動に及ぼす出口水位条件の影響を調べた。出口水位条件が管路内の圧力変動に与える影響と空気塊の関係について考察を行った結果、出口水位が管路天端よりも高い場合に生じるスパイク状の大きな圧力変動(エアハンマー現象)は、出口からの距離が空気塊間隔よりも近い場所までしか伝播しないことが分かった。また、既存の水塊発生理論と管路内水面形モデルを用いて、管内径と管長の影響を考慮した分離流と間欠流との遷移条件を与えるモデルを提案し、既存の研究や本研究の実験結果との比較によりその妥当性を明らかにした。

概要 （英文）

The characteristics of air-water two-phase flows have been experimentally studied in a horizontal pipe of 100mm in diameter and 19.5m in axial length with two different water levels at the outlet section. In the first condition [Case-A] the water level was kept lower than the bottom of the pipe, while in the second condition [Case-B] it was set higher than the top of the pipe. The air hammer phenomenon, accompanied by large pressure pulses, arises in the Case-B. In the experiments, the focus was placed on the effects of the water levels on the flow patterns, dynamic properties of large air-bubbles and pressure fluctuations. As a result of the experiments in the Case-B, it was clarified that the large pressure pulses occur near the outlet region of the pipe when a large bubble is released from the outlet and that the effects of the pressure pulses do not extend to the position further than the following bubble. In addition, a theoretical model was proposed to determine the transitional conditions between stratified flows and intermittent flows. Since this model is based on the hydraulic equations for non-uniform flows as well as the usual criterion for slug flows, it enables us to take account of the diameter and the axial length of a pipe when determining the transition between stratified flows and intermittent flows. The validity of the proposed model was confirmed through the comparison with previous and present experimental results.

報告者

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