Fluid-structural analysis of the IFMIF-DONES outlet channel during nominal operation

The IFMIF-DONES (International Fusion Materials Irradiation Facility and DEMO Oriented Neutron Source) facility relies on a single accelerator line to deliver 125 mA of deuteron at 40 MeV to a flowing liquid Lithium (Li) target, where the deuteron beam interacts with a free surface. The high-speed Li jet, reaching up to 15 m/s, must maintain a specific thickness to achieve the desired neutron flux and effectively dissipate heat. The performance of this jet is critical for designing key components, including the target assembly (TAA), nozzle, liquid Li channel, and quench tank (QT). Fluid-structural interaction simulations of the TAA outlet channel has revealed large oscillatory behaviour. This work analyses the dynamic characteristics of the TAA channel with outflowing liquid Li, using fluid-structure interaction simulations to understand and mitigate these oscillations. The scope of this study also extends towards understanding the vibrational effects of having a QT wall in the vicinity of the TAA outlet channel using coupled CFD-FEM simulations with a commercial code Siemens Star-CCM+. Further, the effect of stiffeners on the TAA channel towards decreasing amplitude of the vibratory behaviour is also studied. It has been observed that with increasing gap between the TAA outlet channel and the QT wall, the oscillatory behaviour becomes stable. Also, the stiffeners aid in reduction of the vibration amplitude.