Hydraulic Characterization of the Full Scale Mock-Up of the DEMO Divertor Outer Vertical Target

Abstract

In the frame of the pre-conceptual design activities of the DEMO work package DIV-1 “Divertor Cassette Design and Integration” of the EUROfusion program, a mock-up of the divertor outer vertical target (OVT) was built, mainly in order to: (i) demonstrate the technical feasibility of manufacturing procedures; (ii) verify the hydraulic design and its capability to ensure a uniform and proper cooling for the plasma facing units (PFUs) with an acceptable pressure drop; and (iii) experimentally validate the computational fluid-dynamic (CFD) model developed by the University of Palermo. In this context, a research campaign was jointly carried out by the University of Palermo and ENEA to experimentally and theoretically assess the hydraulic performances of the OVT mock-up, paying particular attention to the coolant distribution among the PFUs and the total pressure drop across the inlet and outlet sections of the mock-up. The paper presents the results of the steady-state hydraulic experimental test campaign performed at ENEA Brasimone Research Center as well as the relevant numerical analyses performed at the Department of Engineering at the University of Palermo. The test facility, the experimental apparatus, the test matrix and the experimental results, as well as the theoretical model, its assumptions, and the analyses outcomes are herewith reported and critically discussed.

Thermofluid-dynamic assessment of the EU-DEMO divertor single-circuit cooling option

“…The most demanding components from the point of view of computational burden are the PFUs and their supports, which are composed of different materials, have very small geometric details and are subject to high thermal fluxes, which require a sufficient number of cells to correctly reconstruct the thermal gradients that develop. Moreover, on the basis of the mesh-independence analyses of the OVT mock-up cooling circuit, discussed in [17], it can easily be deduced that the complete simulation of the two VTs is even impracticable for the water domain itself, not considering the details of the PFU structures and their supports.…”

“…To define suitable equivalent porous media, the workflow detailed in the following was adopted. At first, a detailed simulation of the flow field inside the individual PFUs channel was carried out for each of the two targets considering a 0.6 mm bulk size mesh in line with the requirements described in [17]. The mass flow rate was also considered in the range of ±20% from its average nominal value, calculated as the ratio between the total mass flow rate and the number of PFU assemblies.…”