Effects of Reynolds number and Richardson number on thermal stratification in hot plenum

Thermal transient water tests were performed using a simplified hot plenum model of a pool-type LMFBR to examine the fundamental characteristics of thermal stratification during reactor trips. These tests were divided into two series to clarify the effects of (1) Reynolds number and (2) Richardson number on the behavior of thermal stratification. The results of the first series indicated that the characteristics of thermal stratification were independent of Reynolds number in the range of Re > 104. It was concluded from the results of the second series that the rising speed of the thermal interface and the temperature gradient at the interface varied proportionally with Ri−12 and Ri12, respectively. In addition, large scale internal waves, called internal standing waves, were observed under the condition of Re > 104 and 1 < Ri < 5.