A Simple Empirical Model for Tube–Support Normal Impact Interaction

Abstract

Flow-induced vibration in a steam generator may cause tube–support interaction. This long term interaction is a challenging problem as it may lead to tube fretting-wear and possibly tube failure. An estimation of the normal impact force during tube–support interaction is important to precisely quantify material removal. A precise study of the interaction presents several challenges as a result of the many parameters involved during the interaction, including fluid forces, number and type of supports, and geometry of contact. The present study investigates tube–support interaction using a simple experimental rig, consisting of a tube interacting with a flat support positioned at the tube midspan. The work investigates the normal force–displacement relationship and arrives at an estimation of empirical parameters, associated with the nonlinearity in this relationship. The resulting empirical model is used to simulate tube–support interaction for various gap sizes and excitation forces. Comparison with experiments indicates that using the nonlinear spring–damper model significantly reduces the predicted impact force error, to less than 20%, when compared to experimental tests. Various energy dissipation mechanisms during tube–support interaction, including impact and structural damping are also studied. The effect of impact damping on the tube response is investigated, using the Hunt and Crossley model. Investigation on structural damping suggests that using a higher effective structural damping during tube–support contact, depending upon tube–support gap size, improves the accuracy of the estimation of the tube response, at least for moderate gap sizes.

Investigation on nonlinear dynamics and fatigue damage of a simply supported tube with clearance restriction in tube bundles subjected to two-phase flow

“…Hassan et al [9] calculated the dynamic responses of a multi-span tube with a loosely support considering the effects of the uidelastic forces and turbulence. Azizian and Mureithi [10] presented an experimental study to investigate the tube-support interaction between the tube and the support structure. Sadath et al [11] studied the dynamics of two loose supported tubes subjected to crossow.…”

Supercritical and Subcritical Hopf Bifurcations in a Delay Differential Equation Model of a Heat-Exchanger Tube Under Cross-Flow

“…Some examples are found in Refs. [22][23][24]. As quoted by Paidoussis and Li [9]-"supports in real heat exchangers are somewhere between a simple support and a clamped one, and exact integral relationships between frequencies are rather rare."…”