THE TURBULENT MIXING RATE AND THE FLUCTUATIONS OF STATIC PRESSURE DIFFERENCE BETWEEN ADJACENT SUBCHANNELS IN A 2-PHASE SUBCHANNEL FLOW

Turbulent mixing rate between adjacent subchannels in a two-phase how has been known to be strongly dependent on the flow pattern. In this s tudy, how visualization was made to investigate the mechanism of the t urbulent mixing between subchannels in a two-phase flow under hydrodyn amic equilibrium conditions. The test channel was a vertical multiple channel consisting of two identical rectangular subchannels, and the w orking fluids were air and water. It was observed in slug-churn hows t hat a large scale inter-subchannel liquid how occurs in front of the n ose of a large gas bubble and behind the tail when the bubble axially passes through the subchannel, and thus a high turbulent mixing rate o f the liquid phase results. In order to know driving force of such a l arge scale inter-subchannel flow, measurement of instantaneous static pressure difference between the subchannels was also made. The result showed that there is a close relationship between the liquid phase tur bulent mixing rate and the magnitude of the pressure difference fluctu ations. (C) 1997 Elsevier Science S.A.