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Influence of straight nozzle geometry on the supersonic under-expanded gas jets

Chen, Fang and Allou, Alexandre and Douasbin, Quentin and Selle, Laurent and Parisse, Jean Denis Influence of straight nozzle geometry on the supersonic under-expanded gas jets. (2018) Nuclear Engineering and Design, 339. 92-104. ISSN 0029-5493

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Official URL: https://doi.org/10.1016/j.nucengdes.2018.09.003

Abstract

The sodium-cooled fast nuclear reactor (SFR) is one of the most promising designs of the fourth generation (Gen IV) nuclear power reactors. Sodium-gas heat exchangers (SGHE) using nitrogen is being investigated as an alternative to improve operational safety associated with the use of steam Rankine cycles. This alternative eliminates the potential risk of chemical reactions. It is known that cracks inside an SGHE can cause the accidental leakage of nitrogen into the sodium-side. Due to the pressure difference between the secondary and tertiary loops, this nitrogen jet is therefore under-expanded. When the nitrogen leak is strong enough to flush the liquid sodium outside the SGHE channel, the nitrogen jet can be considered as single-phase. In this context, this work focuses on the influence of geometrical parameters of cracks (size, cross-section shape, transverse locali- zation and inclination angle) on the impinging under-expanded nitrogen jet and its shock-wave system. A nu- merical study of impinging under-expanded nitrogen jet has been carried out using large eddy simulation (LES) technique. We applied a stagnation pressure upstream of the crack of 180 bar while the nozzle pressure ratio (NPR) ranged from 6.0 to 9.2. We were able to identify the link between the nozzle geometry and the Mach disk diameter and its localization. The vorticity distribution at the nozzle can be used to explain the structure of the jets and the entrainment. The central cross-section of the gas jet tends to turn 45° and 90° for square and rectangular cross-section nozzles respectively. The Taylor-Görtler instability is enhanced with a reduction in the nozzle diameter. These instabilities are also increased with square, rectangular and inclined nozzles.

Item Type:Article
Additional Information:This is an open access article under the CC BY-NC-ND license : https://creativecommons.org/licenses/by-nc-nd/4.0/. Thanks to Elsevier editor. The definitive version of this document is available at: https://www.sciencedirect.com/science/article/pii/S0029549318309919
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Commissariat à l'Energie Atomique et aux énergies alternatives - CEA (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > École de l'air (FRANCE)
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Deposited On:26 Mar 2019 14:23

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