Methodology of local instantaneous interfacial velocity measurement in multi-dimensional two-phase flow

多次元二相流における局所の瞬時界面速度計測法

Shen, X.*; 三島 嘉一郎*; 中村 秀夫  

Shen, X.*; Mishima, Kaichiro*; Nakamura, Hideo

気液二相流では気液各相の運動量,熱,質量が気液界面を通じて密接に結びついているため、界面パラメータを正確に把握する必要がある。とりわけ界面の速度は、界面面積濃度など主要なパラメータの評価において中心的役割を果すため、二相流解析では最も重要なパラメータの1つだが、その計測は容易ではない。このため、これまでに開発した界面計測理論を複数の4センサープローブの利用に拡張することで、特に、3つの独立したプローブを用いた局所の瞬時3次元2相流界面速度計測法を提案する。ところで、5つ以上のセンサーを有するプローブは、センサーを共有することで3つの独立した4センサープローブと見なせるため、5センサーないし6センサープローブで提案する計測法が構築できる。ここでは、6センサープローブを開発し、3次元の水/空気二相流計測に応用した。その結果、差圧計等を用いた平均的計測法との比較により、開発した計測手法が精度よく二相流計測を行えることを確認した。

Since the transport of momentum, heat and mass tightly links with local interfacial characteristics it is essential to know the local interfacial parameters in various two-phase flows. The interfacial velocity plays a determinant role in determining the other interfacial parameters such as the interfacial area concentration and so on. It is accordingly one of the most important parameters in analyzing two-phase flow. However, it also is one of the most difficult parameters to measure up to now. Based on the application of the interfacial measurement theorem to several four-sensor probes, the present study established a theoretical foundation of the measurement method for the local instantaneous interfacial velocity in multi-dimensional two-phase flow by using three independent four-sensor probes. Since we can find three independent four-sensor probes in a multi-sensor probe, which has more than four sensors, by sharing the sensors of the first four-sensor probe with the sensors of the others, a five- or six-sensor probe including at least one set of three four-sensor combinations was recommended to measure the local instantaneous interfacial velocity, interfacial area concentration and so on in multi-dimensional two-phase flow. A six-sensor probe was developed and employed in the practical measurement in an air-water multi-dimensional two-phase flow in a pool. The six-sensor probe measurements were checked against the gas flow rate measurement using a rotameter and a manometer. The comparing results were very satisfactory.