抄録
A gas-liquid two-phase flow through vertical sudden contraction pipe is an area that still little is known and less has been studied experimentally or numerically. The drag and its reduction for an upward bubbly two-phase flow in a sudden contraction pipe are studied. As known, vortices are caused just before and after the contraction and affect significantly the flow characteristics. A small obstacle (ring) is mounted before the contraction in order to smoothen the flow and to control it as a simple and economical method. The effects of ring position, Reynolds number and void fraction are examined and positive results can be observed in all conditions. Moreover, the fluctuation phenomenon caused after the contraction is examined.
