Effect of flow-induced vibration on local flow parameters of two-phase flow

A preliminary study was conducted experimentally in order to investigate th e effect of flow-induced vibration on flow structure in two-phase flow. Two kinds of experiments were performed, namely 'reference' (no vibration) and 'vibration' experiments. In the reference experiment, an experimental loop was fixed tightly by three structural supports, whereas the supports were loosen a little in the vibration experiment. In the vibration experiment vi bration was induced by flowing two-phase mixture in the loop. For relativel y low superficial liquid velocity, flow-induced vibration promoted the bubb le coalescence but liquid turbulence energy enhanced by the vibration might not be enough to break up the bubble. This leaded to the marked increase o f Sauter mean diameter, and the marked decrease of interfacial area concent ration. Accordingly, flow-induced vibration changed the void fraction profi le from 'wall peak' to 'core peak' or 'transition', which increased distrib ution parameter in the drift-flux model. For high superficial liquid veloci ty, shear-induced liquid turbulence generated by two-phase flow itself migh t be dominant for liquid turbulence enhanced by flow-induced vibration. The refore, the effect of flow-induced vibration on local flow parameters was n ot marked as compared with that for low superficial liquid velocity. Since it is anticipated that flow structure change due to flow-induced vibration would affect the interfacial area concentration, namely interfacial transfe r term, further study may be needed under the condition of controlled flow- induced vibration. (C) 1998 Elsevier Science S.A. All rights reserved.