Abstract

Pressurized thermal shock (PTS) modelling has been identified as one of the most important industrial needs related to nuclear reactor safety. A severe PTS scenario limiting the reactor pressure vessel (RPV) lifetime is the cold water emergency core cooling (ECC) injection into the cold leg during a loss of coolant accident (LOCA). Since it represents a big challenge for numerical simulations, this scenario was selected within the European Platform for Nuclear Reactor Simulations (NURESIM) Integrated Project as a reference two-phase problem for computational fluid dynamics (CFDs) code validation. This paper presents a CFD analysis of a stratified air-water flow experimental investigation performed at the Institut de Mécanique des Fluides de Toulouse in 1985, which shares some common physical features with the ECC injection in PWR cold leg. Numerical simulations have been carried out with two commercial codes (Fluent and Ansys CFX), and a research code (NEPTUNE CFD). The aim of this work, carried out at the University of Pisa within the NURESIM IP, is to validate the free surface flow model implemented in the codes against experimental data, and to perform code-to-code benchmarking. Obtained results suggest the relevance of three-dimensional effects and stress the importance of a suitable interface drag modelling.

Highlights

  • The European Platform for Nuclear Reactor Simulations (NURESIM) Integrated Project aims at developing a common European Standard Software Platform for modelling, recording, and recovering computer simulation data for current and future nuclear reactor systems [1]

  • Since Pressurized thermal shock (PTS) has been identified as one of the most important aspects related to nuclear reactor safety, some relevant PTS scenarios were chosen as reference test cases for computational fluid dynamics (CFDs) code validation within the NURESIM integrated project (IP) [5, 6]

  • To validate the two-phase models implemented in NEPTUNE CFD V1.0.6, numerical simulation results were compared with both experimental data and predictions from two commercial CFD codes, namely, ANSYS CFX 10.0 and FLUENT 6.1

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Summary

INTRODUCTION

The European Platform for Nuclear Reactor Simulations (NURESIM) Integrated Project aims at developing a common European Standard Software Platform for modelling, recording, and recovering computer simulation data for current and future nuclear reactor systems [1]. NEPTUNE [2] is the thermal-hydraulics tool of NURESIM, and is designed to simulate two-phase flow in all situations encountered in nuclear reactor power plants. Since PTS has been identified as one of the most important aspects related to nuclear reactor safety, some relevant PTS scenarios were chosen as reference test cases for CFD code validation within the NURESIM IP [5, 6]. This paper deals with the study of a stratified air-water flow experiment performed at the Institut de Mecanique des Fluides de Toulouse in 1985 [7, 8]; this flow configuration is likely to share common physical features with the chosen PTS scenario. To validate the two-phase models implemented in NEPTUNE CFD V1.0.6, numerical simulation results were compared with both experimental data and predictions from two commercial CFD codes, namely, ANSYS CFX 10.0 and FLUENT 6.1

EXPERIMENTAL FACILITY AND TESTS
Preliminary results of two-phase calculations
Experimental data understanding
Single-phase analysis
Single-phase water flow
Single-phase air flow
T250 EXPERIMENTAL TEST SIMULATION WITH NEPTUNE CFD
Findings
CONCLUSIONS
Full Text
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