Improved Accuracy for Two-Phase Downflow Scenarios

Conference · Mon Oct 01 04:00:00 EDT 2012

OSTI ID:1060995

Davis, Cliff B

Problems have been reported for very high downflows in small and intermediate pipes in the bubbly and slug flow regimes. When the flow rate is near critical, the calculated mass flow rate depends strongly on the flow orientation for small and intermediate pipes, whereas the flow rate is nearly independent of flow direction for large pipes. At very high flow rates, the flow is expected to be nearly homogenous and hence to be nearly independent of flow direction. The flow rates calculated by RELAP5-3D agree with this expectation except for downflow in small and intermediate pipes, where the calculated flows in the downward direction are about 20% lower than the flows in the upward and horizontal directions. The problem was traced to an extrapolation of the EPRI drift flux correlation beyond the range of its database. The problem was corrected by creating a very high downflow regime. The EPRI correlation is replaced by the Zuber-Findlay churn turbulent and Kataoka-Ishii drift flux correlations in the very high downflow regime for small and intermediate pipes.

• Research Organization: Idaho National Laboratory (INL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC07-05ID14517
• OSTI ID: 1060995
• Report Number(s): INL/CON-12-27023
• Country of Publication: United States
• Language: English

Related Subjects

97 MATHEMATICS AND COMPUTING
Downflow
RELAP5-3D
Two-Phase