WALMIR MAXIMO TORRES
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Artigo IPEN-doc 29684 Computational fluid dynamics analysis of an open-pool nuclear research reactor core for fluid flow optimization using a channel box2023 - SCURO, N.L.; ANGELO, G.; ANGELO, E.; PIRO, M.H.A.; UMBEHAUN, P.E.; TORRES, W.M.; ANDRADE, D.A.A channel box installation in the IEA-R1 research reactor core was numerically investigated to increase fluid flow in fuel assemblies (FAs) and side water channels (SWCs) between FAs by minimizing bypasses in specific regions of the reactor core, which is expected to reduce temperatures and oxidation effects in lateral fuel plates (LFPs). To achieve this objective, an isothermal three-dimensional computational fluid dynamics model was created using Ansys CFX to analyze fluid flow distribution in the Brazilian IEA-R1 research reactor core. All regions of the core and realistic boundary conditions were considered, and a detailed mesh convergence study is presented. Results comparing both scenarios are presented in the percentage of use of the primary circuit pump. It is indicated that 21.4% of fluid bypass to unnecessary regions can be avoided with the channel box installation, which leads to the total mass flow from the primary circuit for all FAs increasing from 68.9% (without a channel box) to 77.6% (with a channel box). For the SWCs, responsible for cooling LFPs, an increment from 9.7% to 22.4%, avoiding all nondesired cross three-dimensional effects, was observed, resulting in a more homogeneous fluid flow and vertical velocities. It was concluded that the installation of a channel box numerically indicates an expressive mass flow increase and homogeneous fluid flow distribution for flow dynamics in relevant regions. This gives greater confidence to believe that lower temperatures, and consequently oxidation effects in LFPs, can be expected with a channel box installation.Artigo IPEN-doc 17556 Comparison between experimental data and numerical modeling for the natural circulation phenomenon2011 - SABUNDJIAN, GAIANE; ANDRADE, DELVONEI A. de; UMBEHAUN, PEDRO E.; TORRES, WALMIR M.; MACEDO, LUIZ A.; CONTI, THADEU N.; MESQUITA, ROBERTO N. de; ANGELO, GABRIELArtigo IPEN-doc 18093 A numerical and three-dimensional analysis of steady state rectangular natural circulation loop2012 - ANGELO, G.; ANDRADE, D.A.; ANGELO, E.; TORRES, W.M.; SABUNDJIAN, G.; MACEDO, L.A.; SILVA, A.F.Free convection circuits or natural circulation systems are employed in several engineering fields. In nuclear reactors, natural circulation can be used as a passive safety system or as a main heat transfer mechanism. This work presents the results of a three-dimensional numerical analysis of a steady state rectangular natural circulation loop located at the Instituto de Pesquisas Energéticas e Nucleares/Comissão Nacional de Energia Nuclear (IPEN/CNEN-SP). Numerical results and experimental data present in this paper are discussed and compared. The model is good enough to capture 3-D effects, such as the formation of vortex structures and swirl effects.Artigo IPEN-doc 18189 Classification of natural circulation two-phase flow patterns using fuzzy inference on image analysis2012 - MESQUITA, R.N. de; MASOTTI, P.H.F.; PENHA, R.M.L.; ANDRADE, D.A.; SABUNDJIAN, G.; TORRES, W.M.; MACEDO, L.A.