Cavitation damage in narrow channel

Naoe, Takashi   ; Futakawa, Masatoshi  

Cavitation damage is a crucial issue for realizing stable operation in the high-power spallation neutron source, because the damage reduces structural integrity of the target vessel. Double wall beam window is adopted for the next target vessel. The double wall structure is expected to prolong the lifetime of the target vessel by increasing the inner wall thickness. A damage reduction effect between the outer and the inner walls of the beam window is also expected. In order to demonstrate the effect of double wall, we conducted damage tests in the stagnant mercury with parametrically changing the gap width and the machine power. The experimental result showed that the cavitation damage formed between the two walls was reduced with decreasing the gap width. This may be caused by the suppression of cavitation bubble growth by the wall. The mechanisms of the damage reduction in the narrow channel were studied through the experiment and the numerical simulation.