Experiments and computations of a loosely supported tube under two-phase buffeting and fluid-elastic coupling forces
Résumé
In a recent paper we addressed the problem of predicting the nonlinear vibro-impact responses of loosely
supported heat-exchanger tubes subjected to single-phase turbulence and fluid-elastic coupling forces from
transverse flows. Here, we extend that previous work to two-phase flows, by presenting nonlinear time-domain
predictive computations, as well as validation experiments, of the vibro-impacting dynamical tube responses, when subjected to the combined action of two-phase random buffeting excitation and fluid-elastic coupling forces. Emphasis is on the fluid-elastic modeling within a time-domain nonlinear framework, as well as on the stabilizing effect of impacts on the fluid-elastic coupling forces. Computations of the vibro-impacting regimes of a flow-excited cantilever test tube, within a rigid 3x5 square bundle, are based on the experimentally identified two-phase fluidelastic coupling force coefficients and random excitation spectra, as a function of the homogeneous flow velocity, for a void fraction of 85 %. Computations are then compared with the experimental vibratory responses, enabling a satisfying preliminary validation of the modeling approach for two-phase flows.