engleski

BOILING FLOW SIMULATIONS FOR DEBORA EXPERIMENT USING EULERIAN CFD APPROACH

To find an appropriate closure and boiling model for subcooled convective boiling flow, CFD simulations based on an Eulerian approach have been performed for the DEBORA experiment, in which upward flow in a vertical heated pipe with the inner diameter of 19.2 mm and the length of 3.5 m was investigated. We developed a modified zero-closure model, which was implemented into Ansys Fluent® code via user defined functions. The main difference between the original and our zero-closure modified model lies in the modeling of the lift-force coefficient. We focused on four selected experimental cases representing different tendency in void fraction profile at the elevation of the outlet, i. e., higher/lower void at the pipe center than that near the wall region. A grid dependency study was first undertaken, followed by a sensitivity analysis of the liftforce coefficient. The modified model could correctly capture the tendency of the void profile, which was not predicted by the original zero-closure model. This result implies the feasibility of the zero-closure model to accurately estimate the subcooled boiling flow through further improvement of its coefficients.

Two phase flow, Computational fluid dynamics, Convective boiling, Eulerian approach, Phase change

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