Nuclear Engineering and Technology

  • 제52권11호
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  • Pages.2479-2490
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  • 2020
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  • 1738-5733(pISSN)
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  • 2234-358X(eISSN)
한국원자력학회 (Korean Nuclear Society)
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Modified mixing coefficient for the crossflow between sub-channels in a 5 × 5 rod bundle geometry

  • Lee, Jungjin (Department of Mechanical Engineering, Seoul National University) ;
  • Lee, Jun Ho (Department of Mechanical Engineering, Seoul National University) ;
  • Park, Hyungmin (Department of Mechanical Engineering, Seoul National University)
  • 투고 : 2019.06.20
  • 심사 : 2020.05.04
  • 발행 : 2020.11.25
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초록

We performed experiments to measure a single-phase upward flow in a 5 × 5 rod bundle with spacer grids using a particle image velocimetry, focusing on the crossflow. The Reynolds number based on the hydraulic diameter and the bulk velocity is 10,000. The ratio of pitch between rods and rod diameter is 1.4 and spacer grid is installed periodically. The turbulence in the rod bundle results from the combination of a forced mixing and natural mixing. The forced mixing by the spacer grid persists up to 10Dh from the spacer grid, while the natural mixing is attributed to the crossflow between adjacent subchannels. The combined effects contribute to a sinusoidal distribution of the time-averaged stream-wise velocity along the lateral direction, which is relatively weak right behind the spacer grid as well as in the gap. The streamwise and lateral turbulence intensities are stronger right behind the spacer grid and in the gap. Based on these findings, we newly defined a modified mixing coefficient as the ratio of the lateral turbulence intensity to the time-averaged streamwise velocity, which shows a spatial variation. Finally, we compared the developed model with the measured data, which shows a good agreement with each other.

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참고문헌

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피인용 문헌

  1. Experimental investigation of turbulent flow characteristics in cross-flow planes of a 5 × 5 rod bundle with a spacer grid vol.87, 2020, https://doi.org/10.1016/j.ijheatfluidflow.2020.108757