DRIFT-FLUX CORRELATION FOR A ROD BUNDLE GEOMETRY

摘要

A rod bundle drift-flux correlation is developed with intended application across a wide range of two-phase flow conditions. Special consideration is made for fluid flow mechanisms at low liquid velocity and low pressure conditions. In these instances, gravitational forces from the density difference of the associated fluid phases are more significant. Secondary flow patterns may develop as a result and a drift-flux correlation would need to make appropriate adjustments. Earlier correlations may have increased error at these conditions if they have been formulated with respect to relatively higher pressure or flow rate. In the present work, area-average void fraction data at low liquid velocity and low pressure conditions is considered. This data was collected from an adiabatic 8×8 rod bundle test facility. Superficial liquid velocity ranged from 0 to 1.0 m/s and superficial gas velocity ranged from 0.030 to 10.0 m/s. A distribution parameter correlation is developed with respect to this data, an existing drift velocity correlation, and the kinematic constitutive relation of the drift-flux model. Initial analysis of the new correlation demonstrates more appropriate gas velocity calculations than earlier correlations. The drift velocity and distribution parameter dependence on void fraction is also shown in order to demonstrate any physical inconsistencies. Overall, considering the effects of secondary flow patterns may warrant a drift flux correlation as more appropriate in low pressure and low liquid velocity conditions.