A new model for damping controlled fluidelastic instability in heat exchanger tube arrays

Abstract

Heat exchnager tube arrays are susceptible to damage due to flow-induced vibration, with fluidelastic instability the potnetially the most destructive mechanism. In this paper a simple wake model consisting of a convecting vortex sheet is proposed to represent the transient nature of fluidelastic forces present in a tube array. Using this model, the memory function proposed by Granger and Paidoussis has been obtained without the need to calibrate the model with experimental data. The resulting function is found to compare well with the first and second order empirical approximations. The memory function has been combined with experimental data for the static fluid force to produce a prediction of the critical velocity for a range of mass damping parameter. This stability threshold is in reasonable agreement with experimental data. Therefore it is concluded that vorticity transport may well form part of the underlying mechanism responsible for damping controlled fluidelastic instability, as previously proposed.