Speaker
Eiji Hoashi
(Osaka University)
Description
A high-speed liquid metal lithium jet (Li jet) with a free surface is planned as a target irradiated by two deuteron beams to generate a neutron field in an accelerator based neutron source, such as that in the international fusion materials irradiation facility (IFMIF). In the IFMIF, it is desirable to stabilize the Li jet for the efficiency of the neutron generation and the safety of facilities, and we have been thus studying characteristics of the Li jet experimentally and numerically. Especially, in order to understand observed phenomena experimentally, it is important to obtain the information on the inner flow structure of the opaque Li jet using a simulation. The Li jet flows out from a two-staged contraction nozzle, which is used for reducing a thickness of a boundary layer of the Li jet at the nozzle exit. In previous numerical study, it was found that longitudinal vortices due to hydrodynamic instability at concave walls were generated inside the boundary layer of the nozzle in the Li jet velocity of 15 m/s. In addition, the random pattern of the surface wave on the Li jet in this case was also caused by both the relaxation of the free shear stress layer under the free surface and these vortices mentioned above. In this paper, we will present results of the simulation model extended to 100 mm downstream from the nozzle exit in the jet part length and 5 mm in the model width. As a result, it was found that vortices under the Li jet surface and at the bottom of the Li jet were coalesced and dissipated as flowing downstream and that the random surface fluctuation could be confirmed at points of 55 and 95 mm downstream from the nozzle exit as well as experimental results.
Co-authors
Eiji Hoashi
(Osaka University, 2-1 Yamadaoka, Suita-City, Osaka, Japan)
Hiroo Kondo
(Japan Atomic Energy Agency, 4002 Narita, O-arai, Ibaraki, Japan)
Hiroshi Horiike
(Fukui University of Technology, 3-6-1 Gakuen, Fukui-City, Fukui, Japan)
Masaru Kaginaka
(Osaka University, 2-1 Yamadaoka, Suita-City, Osaka, Japan)
Nobuo Yamaoka
(Osaka University, 2-1 Yamadaoka, Suita-City, Osaka, Japan)
Sachiko Yoshihashi
(Fukui University of Technology, 3-6-1 Gakuen, Fukui-City, Fukui, Japan)
Takafumi Okita
(Osaka University, 2-1 Yamadaoka, Suita-City, Osaka, Japan)
Takuji Kanemura
(Japan Atomic Energy Agency, 4002 Narita, O-arai, Ibaraki, Japan)
