Numerical prediction of pressure loss in tight-lattice rod bundle by use of 3-dimensional two-fluid model simulation code ACE-3D

Yoshida, Hiroyuki  ; Suzuki, Takayuki*; Takase, Kazuyuki

In this paper, boiling two-phase flow analysis in a tight-lattice rod bundle was performed by the ACE-3D. In the results, the void fraction in an outermost region of the rod bundle is lower than that in a center region of the rod bundle. The tendency of void fraction distributions agreed with the measurement results by neutron radiography qualitatively. Moreover the pressure distribution in a horizontal plane induced by the void fraction distribution was the cause of bubble movement from the gap region to the subchannel region. The predicted pressure loss in the axial section without spacers accorded with experimental results with a difference of around 10%. The predicted friction pressure loss was underestimated around 20% of measured values, and the effect of the turbulence model is considered as one of the causes of this underestimation.