Prediction of Cross Flow Due to Coolant Channel Blockages

Computer programs such as COBRA IIIC, which handle flow blockages, use a transverse momentum balance on a control volume of uniform width connecting any two subchannels to evaluate cross flow and momentum exchange effects on axial flow distribution. The transverse momentum balance employed has several constants that need to be determined empirically. This Note describes the method to develop such a correlation for three blockage configurations. It was found that with a constant width control volume, the data could not be satisfactorily correlated. A variable width control volume was therefore used to correlate the data behind flow blockage. A similar correlation could be developed ahead of the blockage but is not completed yet. Although the applicability of the correlation is limited to the blockage configurations analyzed, the variable width control volume method of correlating data that has evolved from this study is of general use in correlating such data.