Session: FSI-02-03 Flow-induced Vibration III

Paper Number: 62693

Start Time: Wednesday, July 14, 2021, 08:00 PM

62693 - Turbulence-Induced Vibration of Tube Bundles Subjected to Cross-Flow and Loose Support 

Flow-induced vibration of the tube bundles is an important issue in the security of a steam generator. Several investigations were performed to study the fluidelastic instability of the tube subjected to cross-flow. It should be noted that turbulence-induced vibration of the tube bundles subjected to cross-flow and loose support may cause a potential tube fretting wear and fretting fatigue when the flow pitch velocity is lower than the threshold of the fluidelastic instability. However, there is seldom theoretical analysis to study the vibration characteristics of the tube bundles considering the effect of the loose support. Therefore, a mathematical model of a single flexible tube in tube bundles subjected to turbulence random force and loose support was presented in this paper. An experiment was carried out to obtain the turbulence random forces acting on the tube bundle both in the entrance and intermediate regions. The influences of the turbulence force on the vibration characteristics of the tube were investigated. From these analyses, we have drawn the following conclusions:

1.      New boundaries spectra of equivalent power spectral density of the random excitation force per unit length (EPSD) resulting from cross-flow for tube bundles in the entrance and intermediate regions were obtained.

2.      With increasing flow pitch velocity below the threshold of the fluidelastic instability, the amplitude of the turbulence-induced vibration of the tube increases monotonously.

3.      The vibration amplitudes and the maximum RMS stresses of the tube in the entrance region are much larger than those in the intermediate region, which demonstrates that the loose support has a significant impact on the dynamic response of the tube bundles in the entrance region. Thus, the turbulence excitation force should be considered when investigating the nonlinear dynamics of the tube bundles subjected to cross-flow and loose support.

Presenting Author: Jiang Lai Nuclear Power Institute of China

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