| Popis: |
In the frame of investigating vibration issues that can concern nuclear steam generator U-tubes, coupled fluid-structure numerical simulations could represent a powerful tool. Steam generator tube bundles can be concerned by both turbulence-induced vibrations and fluidelastic instability. In this paper, a single-phase flow is considered and a URANS approach is retained for the fluid modeling. Despite URANS approaches are generally not expected to be able to consistently predict turbulence-induced forces, they could still represent a proper tool to evaluate vortex shedding and fluidelastic instability. The present numerical simulations are performed on an experimental configuration of 7 × 7 straight tube bundle, square pitch, subjected to water cross-flow. Only one tube — the central one — is flexible in both drag and lift directions, all the other tubes being fixed. The structure displacements are taken into account through an ALE approach. 2-way fluid-structure coupling is employed. The goal of the paper is to assess the consistency of FSI numerical simulation for cross-flow configurations, based on fluid URANS approach. To do that, the numerical and experimental results are first compared in terms of vibration response, as a function of the fluid gap velocity. The fluid force cross-correlation and spectrum are then analysed and discussed, in order to understand the behaviour of the URANS approach and the fluid force mechanisms captured. |
