On flow induced vibrations in hydraulic structures and their alleviation

Abstract

Flow-induced vibrations are characterized as dynamic response, self-controlled and self-excited vibrations, the latter two being the principal subjects of this paper. Such classification is shown to be a helpful guide for designing against destructive vibrations. While the obvious choices of increased stiffness or additional damping may prove effective in some cases, counter-examples are presented. A change in structural geometry which modifies the flow characteristics may be the best or only avenue for eliminating vibration problems in service.The general nature of mathematical models of these phenomena is presented briefly as well as those aspects of hydro-elasticity which distinguishes it from aeroelasticity. In particular, the effects of virtual mass are emphasized.A variety of different problems are reviewed with an effort to summarize and interpret current knowledge and to provide some physical insight. Specifically treated are stability of fluid-conveying pipes, vibrations of hydraulic gates, valves, and seals, and the singing of propellor blades, guide vanes, and control surfaces. In each case, methods of alleviation are discussed.