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Kondo, Hiroo*; Kanemura, Takuji*; Park, C. H.*; Oyaizu, Makoto*; Hirakawa, Yasushi; Furukawa, Tomohiro
Fusion Engineering and Design, 146(Part A), p.285 - 288, 2019/09
Times Cited Count：1 Percentile：10.81(Nuclear Science & Technology)Herein, the wall shear stress in a double contraction nozzle has been evaluated experimentally to produce a liquid lithium (Li) target as a beam target for intense fusion neutron sources such as the International Fusion Materials Irradiation Facility (IFMIF), the Advanced Fusion Neutron Source (A-FNS), and the DEMO Oriented Neutron Source (DONES). The boundary layer thickness and wall shear stress are essential physical parameters to understand erosion-corrosion by the high-speed liquid Li flow in the nozzle, which is the key component in producing a stable Li target. Therefore, these parameters were experimentally evaluated using an acrylic mock-up of the target assembly. The velocity distribution in the nozzle was measured by a laser-doppler velocimeter and the momentum thickness along the nozzle wall was calculated using an empirical prediction method. The resulting momentum thickness was used to estimate the variation of the wall shear stress along the nozzle wall. Consequently, the wall shear stress was at the maximum in the second convergent section in front of the nozzle exit.
Hirakawa, Yasushi; Furukawa, Tomohiro; Park, C.-H.*; Kondo, Hiroo*; Oyaizu, Makoto*
no journal, ,
A cavitation phenomenon-like acoustic noise was reported in the downstream conduit of Li target assembly of the IFMIF/EVEDA lithium test loop (ELTL), which aims to verify the Li target being intended for use as a beam target for the intense fusion neutron sources. To clarify the cause of this cavitation phenomenon, we found that acoustic emissions due to cavitation occurred in a narrow area near the start of the bend-pipe where the Li target impinged by using acoustic-emission sensors. And the method to determine this conflict location was formulated. We evaluated the applicability of the proposed numerical method by simulating the cavitation phenomenon occurring in the downstream conduit of the ELTL. As a result, the area of occurrence of the cavitation phenomenon was estimated by specifying the area of decompression/boiling inside the liquid Li and the point of collision with the inner wall of the conduit. And the collision point was the same as the specific position using the AE sensor. In addition, a more stable and easy-to-maintain design was proposed by using a tilted straight-type's downstream conduit to suppress the occurrence of cavitation.
