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 instability of a tube in a heat exchanger is controlled using a tunable damper and the stiffness and damping associated with the flow-induced non-linearities are determined using the force-state mapping technique. The analysis of the results clearly indicates a linear destabilising fluid mechanism but also identifies non-linear damping and stiffness forces which are consistent with both the experimental behaviour and theoretical models for the instability.