Application of force-state mapping to a non-linear fluid-elastic system

The damping mechanisms associated with flow/structure interactions are, in general, considered to be non-linear. In this paper, the fluid-elastic inst ability of a tube in a heat exchanger is controlled using a tunable damper and the stiffness and damping associated with the flow-induced non-linearit ies are determined using the force-state mapping technique. The analysis of the results clearly indicates a linear destabilising fluid mechanism but a lso identifies non-linear damping and stiffness forces which are consistent with both the experimental behaviour and theoretical models for the instab ility. (C) 2001 Academic Press.