Flow Pattern of Gas-Liquid Two-Phase Flow in a Horizontal U bend Pipe

In some horizontal steam generators or refrigerators, a gas-liquid two-phase flow is observed in horizontal U bend pipelines which consist of U bends, upper horizontal pipes and lower horizontal pipes installed just under the upper horizontal pipes. Liquid is generated due to condensation of steam in pipes if they are used as condensers. It is supposed that flow patterns in the horizontal parts of these pipelines are different from those in the horizontal pipes without U bend. Hence, it is necessary to study and observe the flow pattern in horizontal parts and U bend part. In the present study, an experimental investigation was carried out using a horizontal U bend pipeline which has a water supply section at midway of lower horizontal pipe. Flow patterns were observed at four parts including U bend part and horizontal parts. The effects of radius of the U bend on the flow pattern were made clear. The flow patterns and the presented maps were compared with those in the previous studies.