Overview: Free surface measurement with renewed nozzle of Osaka Li loop

Characteristics of surface waves on a high-speed liquid lithium (Li) flow have been examined using a Li circulation loop at Osaka University for the International Fusion Materials Irradiation Facility (IFMIF). For the purpose of detailed study of the flow and advanced diagnostics, nozzle and viewing ports were modified. The new test section is equipped with a large port, which enables us working on the nozzle and continuous flow observation from the nozzle exit to 240 mm downstream from that, including the beam axis of IFMIF target at 175 mm. The old nozzle edge was damaged due probably to erosion/corrosion by Li flow. And damages may generate many surface wakes from them and disturbed assessment of expected free surface shapes in IFMIF. In order to measure the free surface shapes from multiple wakes, the nozzle was renewed to mechanically replaceable configuration of the upper part of the nozzle. With this new test section, measurement of surface fluctuations using the electro-contact probe at 175 mm downstream from the nozzle exit, and observation with a high speed video camera were performed. The result showed that surface waves are fairly lower in amplitude than those with the previous nozzle.