A Semi-Discretizing Method Based Efficient Model for Fluidelastic Instability Threshold Prediction of Tube Bundles

摘要

Fluidelastic instability is destructive in tube bundles subjected to cross flow. Flow channel model proposed by Leaver and Weaver is well used for modeling this problem. However, as the tube motion is supposed to be harmonic, it may not simulate the general dynamic behaviors of tubes. To improve this, a model with arbitrary tube motion is proposed by Hassan and Hayder. While, due to involving in the time delay term, the stability problem cannot be solved by the eigenvalue scheme, and time domain responses of the tube have to be obtained to assess the instability threshold. To overcome this weakness, a new approach based on semi-discretizing method (SDM) is proposed in this study to make the instability threshold be predicted by eigenvalues directly. The motion equation of tube is built with considering the arbitrary tube motion and the time delay between fluid flow and tube vibration. A time delay integral term is derived and the SDM is employed to construct a transfer matrix, which transforms the infinite dimensional eigenvalue problem into a finite one. Hence the stability problem become solvable accordingly. With the proposed method, the instability threshold of a typical square tube array model is predicted, and the influences of system parameters on stability are also discussed. With comparing with prior works, it shows significant efficiency improvement in prediction of the instability threshold of tube bundles.