Hybrid Experimental Simulation of Fluid–Elastic Coupling and Vibro-Impact Dynamics in a Gap-Supported Tube for Steam Generator Applications

Steam generator tubes in nuclear power plants are subjected to flow-induced vibrations that may lead to fluid–elastic instability, repeated impacts with support plates, wear, and structural damage. Experimental investigation of such phenomena is often costly and complex due to the need for dedicated fluid test facilities. This paper proposes a reduced-order hybrid experimental technique to reproduce identified modal fluid–elastic effects on a single gap-supported tube without using a fluid loop. The approach combines a physical experimental structure, a numerical model, and a real-time active vibration control system. A pole-placement strategy is used to modify the first modal frequency and damp the structure so that the controlled tube follows the reference pole trajectory identified from previous fluid-flow experiments. The method is first validated in the linear regime by reproducing the main fluid–elastic modal trends, including the vortex-shedding-related pole deviation and the onset of instability. It is then extended to nonlinear configurations involving impacts between the tube and its gap stops. Comparisons with numerical simulations are performed for stable, near-critical, and linearly unstable regimes using spectral responses and impact-force statistics. The results show that the proposed approach provides a controlled experimental framework for studying the interaction between identified fluid–elastic effects and vibro-impact nonlinearities. The present study focuses on reproducing the effects of the fluid on a single tube through a reduced-order experimental configuration. Although it does not represent the complete dynamics of an industrial steam-generator bundle, it constitutes a first step toward the future generalization of the approach to more representative multi-tube configurations.