Avaliação da influência da subcamada viscosa na estabilidade mecânica de placas de elementos combustíveis em condições de escoamento axial por meio de simulações numéricas FSI

Abstract

This work aims at investigating the influence of the viscous sublayer on the mechanical stability of fuel element plates under conditions of axial flow through two-way Fluid- Structure Interaction (FSI) numerical simulations. The adopted methodology follows the approach proposed by Mantecón (MANTECÓN, 2019), who observed a transition from linear to nonlinear behavior in the maximum deflection of plates at their leading edge with the square of the velocity of the coolant fluid in the channel. The velocity at which this transition is identified is the critical velocity (V c ). In order to assess the influence of the viscous sublayer, the CFD domain was discretized from the beginning of its boundary layer. Given that this approach significantly increases computational costs, symmetry boundary conditions were applied wherever geometric and loading characteristics allowed for it. In addition to this approach, the feasibility of solving the FSI problem under steady-state conditions was also investigated. The obtained results confirmed that modeling the boundary layer is sufficient to determine the critical velocity. Furthermore, it is also suggested that the steady-state approach, along with the application of symmetry boundary conditions whenever possible, can be employed to prevent failures due to static deflection in the design of new fuel elements. This would provide support for traditional methods.