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In-plane FEI evaluation method taking into account of friction damping
Shingo Nishida

Last modified: 2018-04-14


Recently, tube-to-tube wear indications of triangular tube bundle steam generators caused by in-plane fluid elastic instability (FEI) have been reported. In the U-bend region of the steam generators with flat bar type supports, friction damping plays dominant role because U-tube is supported only by friction force for in-plane direction. In the conventional way, friction force was evaluated as energy dissipation against external forced excitation. However, in the case of self-excited vibration like SG U-tube, friction damped system shows the characteristics of forced self-excited vibration system intrinsically. Therefore, stability analysis against nonlinear friction force and unstable fluid force is required. We developed evaluation method about this kind of friction damping. Nonlinear numerical simulation was conducted by taking into consideration of friction force and unstable fluid force. Furthermore, we conducted validation test using single tube excitation test facility. Analytical result showed very good agreement with test result. Calculation procedure of friction damping used for FEI evaluation was verified.


tube bundles;friction damping;fluid elastic instability

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