Experimental and Numerical Investigation of Prototypical Multi-Jet Impingement (HEMJ) Helium-Cooled Divertor Modules

A modular helium-cooled divertor design based on the multi-jet impingement cooling concept, known as the helium-cooled multi-jet (HEMJ), has been developed at the Karlsruhe Research Center (FZK). Thermal-hydraulic design simulations have shown that the HEMJ divertor can accommodate an incident heat flux of at least 10 MW/m² with local heat transfer coefficients as high as ~50 kW/(m²K). However, there were no experimental data to validate the calculated thermal performance. An experimental study of the HEMJ divertor was therefore performed at Georgia Tech in collaboration with FZK. An experimental test module duplicating the prototypical HEMJ geometry and material properties was designed, fabricated, instrumented, and tested in an air flow loop at different incident heat flux values. The air flow rate was selected to cover a wide range of Reynolds numbers spanning that for the actual HEMJ, namely 2.1 × 10⁴. The measured temperature distributions and local heat transfer coefficients estimated from these temperature distributions are both in good agreement with numerical predictions of the air-cooled test module performance calculated using FLUENT[registered] 6.2 for all test conditions. This research supports earlier numerical predictions of the thermal performance of the HEMJ design, and provides added confidence in the ability of the FLUENT[registered]CFD package to accurately predict the thermal performance of various gas-cooled plasma-facing components with complex geometry.