A Numerical Investigation of the Thermal-Hydraulics of the Helium-Cooled Modular Divertor with Multiple Jets

Three-dimensional numerical simulations of a test section modeling a single module of the helium-cooled modular divertor with multiple jets (HEMJ) design were performed to complement experimental studies at nearly prototypical conditions as part of the joint US-Japan effort on plasma-facing components evaluation by tritium plasma, heat, and neutron irradiation experiments (PHENIX). The Spalart-Allmaras turbulence model gave numerical predictions of the cooled surface temperature that were in good agreement with experimental estimates from a new helium loop. The simulations showed that spatial variations in incident heat flux, at least in the form of a Gaussian function, had a negligible effect on cooled surface temperatures.

Our initial results indicate that the numerical predictions of the thermal performance of a single HEMJ module are in reasonable agreement with the experimental studies. The simulations do, however, predict slightly higher heat transfer coefficients (HTCs) than the experimental studies, presumably because they do not account for thermal losses. The HTC appears to be essentially independent of incident heat flux, suggesting that the model can be used to investigate parameters that cannot be determined experimentally in many cases, such as the local HTC and temperature distributions within the divertor pressure boundary, at prototypical conditions.