The characteristics of turbulence in the fields of velocity and temperature of the upper plenum of LMFBR have been investigated to estimate the behavior of thermal diffusion near the upper core structure (UCS). An inlet nozzle of a 1/20 scale experimental vessel provided a co-axial water jet with temperature distribution. The two component velocity measurements were carried out by 3 beam laser Doppler velocimetry, where the temperature was simultaneously measured to obtain correlations among fluctuations of velocity and temperature. The results indicated that the higher temperature jet flow did not mix with colder surroundings up to the bottom of the UCS. Remarkable thermal striping could be observed at the edge of UCS bottom. Sufficient turbulent mixing of momentum and heat was realized after the separation at the edge of UCS bottom, since the higher temperature jet flowed slantingly to the lower temperature surrounding jet.
|Transactions of the Japan Society of Mechanical Engineers Series B
|Published - 1986
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