Pressurized Thermal Shock has been identified as one of the most important industria! needs related to nuc!ear reactor safety. A very severe PTS scenario, generating phenomena of Jet Impingement with heat transfer, is the cold water Emergency Core Cooling injection into the cold leg during a LOCA. Numerica! simulations of the PTS phenomena through Computational Fluid Dynamics codes could supply accurate predictions of the thermal load, but it is necessary to verify and validate the applicability ofthese codes in relevant demonstration test-cases. The impinging jet flow represents a particularly challenging case for the validation ofturbulence models. This work presents the study of a sing!e-phase axisymmetric turbulentjet impinging orthogona!!y on a surface, with heat transfer. The problern have been analyzed with two commercia! CFD codes, FLUENT and Ansys CFX, adopting different turbulence models, near wa!1 treatment and mesh refinement in the wall region. Numerica! results have been compared with cxperimcntal data available in the ERCOFTAC database. The numerica! predictions indicate that k — e mode!s generally !ead to far too !arge levels ofturbulence near the stagnatibn point. This exeessive energy in turn induees too much high heat transfer coefficients and turbu!ent mixing with ambient fluid.
Impinging jet studies for turbulent modelling assessment and code benchmarking
D'AURIA, FRANCESCO SAVERIO
2006-01-01
Abstract
Pressurized Thermal Shock has been identified as one of the most important industria! needs related to nuc!ear reactor safety. A very severe PTS scenario, generating phenomena of Jet Impingement with heat transfer, is the cold water Emergency Core Cooling injection into the cold leg during a LOCA. Numerica! simulations of the PTS phenomena through Computational Fluid Dynamics codes could supply accurate predictions of the thermal load, but it is necessary to verify and validate the applicability ofthese codes in relevant demonstration test-cases. The impinging jet flow represents a particularly challenging case for the validation ofturbulence models. This work presents the study of a sing!e-phase axisymmetric turbulentjet impinging orthogona!!y on a surface, with heat transfer. The problern have been analyzed with two commercia! CFD codes, FLUENT and Ansys CFX, adopting different turbulence models, near wa!1 treatment and mesh refinement in the wall region. Numerica! results have been compared with cxperimcntal data available in the ERCOFTAC database. The numerica! predictions indicate that k — e mode!s generally !ead to far too !arge levels ofturbulence near the stagnatibn point. This exeessive energy in turn induees too much high heat transfer coefficients and turbu!ent mixing with ambient fluid.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
