Computationally efficient methodology of 3D thermal-hydraulic analysis of Diagnostic Shielding Module #2 of ITER Equatorial Port #11

Abstract

The process of design justification of Diagnostic Shielding Modules (DSMs) of port plugs of the International Thermonuclear Experimental Reactor (ITER) includes a stage of thermal-hydraulic computational analysis. The ITER tokamak operates in a pulsation mode that means the nuclear heating affecting DSMs is unsteady, and transient analysis is required. Three-dimensional (3D) approaches for fully coupled thermal-hydraulic analysis, which imply simultaneous computations for fluid and solid parts of a 3D DSM model, lead typically to “heavy” numerical models being very expensive from the computational point of view, especially for transient simulations. In order to significantly reduce the consumption of computational resources, the present 3D thermal-hydraulic analysis of DSM #2 of ITER Equatorial Port #11 was performed using one-way coupling. Firstly, steady-state CFD computations of turbulent flow were performed for the front part of DSM cooling system, which is a high-density network of channels of complex geometry. Obtained in CFD analysis map of wall shear stress on surface of channels was then converted into a map of local heat transfer coefficient using a simple and conservative approach based on known empirical correlations for turbulent flow in a circular pipe. For the back part of DSM cooling system, which basically consist of many relatively long channels, an individual (single) value of heat transfer coefficient for each of the channels was directly evaluated using empirical correlation. The heat transfer coefficient maps obtained for both parts of DSM cooling system were used finally as a boundary condition in transient thermal analysis of the solid part of the DSM model. Details and justifications of the described computationally-efficient methodology are presented.