NIKOLAS LYMBERIS SCURO
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Artigo IPEN-doc 28529 RANS-based CFD calculation for pressure drop and mass flow rate distribution in an MTR fuel assembly2021 - SCURO, N.L.; ANGELO, G.; ANGELO, E.; UMBEHAUN, P.E.; TORRES, W.M.; SANTOS, P.H.G.; FREIRE, L.O.; ANDRADE, D.A.This work presents a Reynolds-averaged Navier Stokes–based computational fluid dynamics methodology for the calculation of pressure drop and mass flow rate distribution in a material test reactor flat-plate-type standard fuel assembly (SFA) of the IEA-R1 Brazilian research reactor to predict future improvements in newer SFA designs. The results improve the understanding of the origin of fuel plate oxidation due to high temperatures, and consequently, due to the internal flow dynamics. All numerical analyses were performed with the ANSYS-CFX® commercial code. The observed results show that the movement pin decreases the central channel mass flow due to the length of the vortex at the inlet region. However, the outlet nozzle showed greater general influence in the flow dynamics. It should have a more gradual cross-section transition being away from the fuel plates or a squarer-shaped design to get a more homogeneous mass flow distribution. Optimizing both regions could lead to a better cooling condition. The validation of the IEA-R1 numerical methodology was made by comparing the McMaster University’s dummy model experiment with a numerical model that uses the same numerical methodology. The experimental data were obtained with laser Doppler velocimetry, and the comparison showed good agreement for both pressure drop and mass flow rate distribution using the Standard k-ω turbulence model.Artigo IPEN-doc 24791 Transient cfd analysis of the flow inversion of the nuclear research reactor IEA-R12018 - SCURO, N.L.; SANTOS, P.G.; UMBEHAUN, P.E.; ANDRADE, D.A.; ANGELO, E.; ANGELO, G.The IEA-R1 research reactor works with a downflow direction, but after pumps shutdown during a LOFA test, the reactor shutdown. The heat decay will be removed by natural convection, which is an upward flow, originating flow inversion. Using the Instrumented Fuel Element designed at the Institute for Energy and Nuclear Research (IPEN), the loss of flow accident (LOFA) was analyzed along instrumented fuel plates. The preliminary results showed temperature peaks during inversion, which is as much representative as in nominal operation at 3.5MW. Therefore, these experimental data lead a construction and validation of a transient three-dimensional numerical analysis for a single fuel channel using the ANSYS-CFX® commercial code. The numerical results show improvement in obtaining more properties, e.g., wall heat transfer coefficient, which is usually obtained through empirical correlations.