Theoretical and experimental study on the fluidelastic instability of tube bundles in two-phase cross flow

A theoretical model of the fluidelastic instability of tube bundles in two-phase cross flow is proposed. The model considers the interaction between fluid force and cylinder motion. Through theoretical investigation, the mechanism of fluidelastic instability induced by two-phase flow was revealed, and an experiment was conducted to verify the approach. The effects of the time delay parameter and the tube natural frequency on the critical velocity of fluidelastic instability were also investigated, and the results indicate that both are important factors in this respect. The influence of the time delay parameter on critical velocity is significant, particularly when the void fraction is low. A linear relationship between critical velocity and tube frequency was observed under all tested void fraction conditions. By comparison with previously reported test data, it is demonstrated that the model proposed herein is able to provide an accurate prediction of the fluidelastic instability of a tube array in two-phase flow.