Cfd analyses of various channel concepts to remove heat for the second target station

The Second Target Station at Oak Ridge National Laboratory is designed to produce the world's highest peak brightness neutron source with a short-pulse 700 kW proton beam at 15 Hz using solid rotating tungsten (W) target segments. The W is hipped with tantalum (Ta) clad to minimize corrosion. Advanced computational fluid dynamics models were developed in STAR-CCM+, and multiple cooling channel arrangements were studied to improve heat transfer performance for different proton beam profiles, including normal, off-center, peaked, and diffuse proton beams. The energy depositions in the target segments were calculated from the neutronic analysis. The results from transient heat sources that modeled all proton pulses and equivalent steady-state heat sources were compared, and the peak temperature difference was within +/- 5 degrees C. This paper discusses the effect of Coriolis and centrifugal forces on the rotating target. The results from displacements per atom-dependent thermal conductivity are also compared with that from irradiated W with constant thermal conductivity. The simulation results indicate that the curved side channel design has the best cooling performance and that 34% of bypass flow could occur due to a 1 mm gap from manufacturing tolerance. The two-phase flow simulation also shows that the air trapped in the target during the initial fill-up can be successfully evacuated during normal operation.