A particle finite element method based partitioned paradigm for the axial-flow-induced vibration analysis of NHR200-II fuel rod

Abstract

As a newly designed 200 MW nuclear heating reactor (NHR200-II), flow-induced vibration (FIV) of the fuel rod has attracted extensive attention due to its slender shape and the hydrodynamic loads arose from the turbulent flow of the surrounding fluid. Fretting wear and/or damage of fuel rod induced by FIV would highly affect system operation and nuclear safety. In this article, a particle finite element method (PFEM) based partitioned paradigm (i.e., implicit finite element method for structure dynamics, PFEM for fluid flow, and unsteady Reynolds averaged Navier–Stokes for turbulence modelling) toward FIV problems was proposed, implemented, and validated. Axial FIV of a single NHR200-II fuel rod was then analyzed through this finite-element based framework. Vibration characteristics of the fuel rod against varied turbulent inflow velocities with a constant turbulence intensity Tv of 5% were discussed in detail. The results showed that horizonal displacement is larger than vertical displacement but both within the same order of magnitude. The effect of inflow velocity of 1.0–2.0 m/s on the dominant frequency is also captured. Besides, fluctuating horizonal pressure is identified as the main source of forced vibration. Therefore, reinforcements on the horizontal constraint are recommended to better eliminate the vibration and enhance the reactor safety.