Flow-induced vibration: recent findings and open questions

Component failures due to excessive flow-induced vibration are still affecting the performance and reliability of nuclear power stations. Tube failures due to fretting-wear in nuclear steam generators, and vibration related damage of reactor internals are of particular concern. The purpose of this paper is to review some of the recent findings in the area of flow-induced vibration and to discuss some of the remaining questions. Vibration excitation 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 explained. The statistical nature of some parameters, in particular support conditions, is discussed. The prediction of fretting-wear damage is approached from several points of view. An energy approach to formulate fretting-wear damage is proposed. (C) 1998 Elsevier Science S.A. All rights reserved.