Flow-induced vibration: recent findings and open questions

Component failures due to excessive flow-induced vibration are still affect ing the performance and reliability of nuclear power stations. Tube failure s due to fretting-wear in nuclear steam generators, and vibration related d amage of reactor internals are of particular concern. The purpose of this p aper is to review some of the recent findings in the area of flow-induced v ibration and to discuss some of the remaining questions. Vibration excitati on mechanisms and damping mechanisms are described with particular emphasis on fluidelastic instability and damping in two-phase flows. The need for a better understanding of two-phase flow regimes, particularly in cross flow , is outlined. The dynamic characteristics of nuclear structures are explai ned. The statistical nature of some parameters, in particular support condi tions, is discussed. The prediction of fretting-wear damage is approached f rom several points of view. An energy approach to formulate fretting-wear d amage is proposed. (C) 1998 Elsevier Science S.A. All rights reserved.