Numerical Simulation of Kelvin–Helmholtz Instability and Boundary Layer Stripping for an Interpretation of Melt Jet Breakup Mechanisms

The present study is aimed at investigating the ability of a CFD modeling of liquid–liquid jet breakup to resolve the principal mechanisms relevant to jet breakup as well as submillimeter-scale drop size. It is generally known that jet leading edge breaks up by boundary layer stripping (BLS), and je...

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Main Authors: Min-Soo Kim, Kwang-Hyun Bang
Format: Article
Language:English
Published: MDPI AG 2022-10-01
Series:Energies
Subjects:
Online Access:https://www.mdpi.com/1996-1073/15/20/7517
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author Min-Soo Kim
Kwang-Hyun Bang
author_facet Min-Soo Kim
Kwang-Hyun Bang
author_sort Min-Soo Kim
collection DOAJ
description The present study is aimed at investigating the ability of a CFD modeling of liquid–liquid jet breakup to resolve the principal mechanisms relevant to jet breakup as well as submillimeter-scale drop size. It is generally known that jet leading edge breaks up by boundary layer stripping (BLS), and jet lateral surface breaks up by Kelvin–Helmholtz instability (KHI). The jet breakup rate as well as the resulting particle size are important parameters that would largely govern the intensity of a steam explosion in severe reactor accidents. First, a two-dimensional simulation of KHI along the melt-liquid coolant interface was performed using the VOF model in ANSYS Fluent with fine meshes as small as 0.02 mm. The dominant wavelength obtained by FFT analysis of calculated melt volume fractions showed that the fastest growing wavelength from the linear analysis of KHI is seen only at the very early development of the instability, and it increases gradually. Second, a three-dimensional simulation of BLS was performed, and the shapes and sizes of the melt particles were obtained. The particle size distributions from KHI and BLS simulations were compared with COLDJET experimental data of Woods metal and water, and it showed that the finer drops of one millimeter or smaller are produced by Kelvin–Helmholtz instability, and the drops of a few millimeters in diameter are mainly produced by boundary layer stripping.
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spelling doaj.art-a5ec90e7ec7e4958b07ccb4a1d01a3752023-11-23T23:55:56ZengMDPI AGEnergies1996-10732022-10-011520751710.3390/en15207517Numerical Simulation of Kelvin–Helmholtz Instability and Boundary Layer Stripping for an Interpretation of Melt Jet Breakup MechanismsMin-Soo Kim0Kwang-Hyun Bang1Division of Mechanical Engineering, Korea Maritime and Ocean University, 727 Taejongro, Yeongdogu, Busan 49112, KoreaDivision of Mechanical Engineering, Korea Maritime and Ocean University, 727 Taejongro, Yeongdogu, Busan 49112, KoreaThe present study is aimed at investigating the ability of a CFD modeling of liquid–liquid jet breakup to resolve the principal mechanisms relevant to jet breakup as well as submillimeter-scale drop size. It is generally known that jet leading edge breaks up by boundary layer stripping (BLS), and jet lateral surface breaks up by Kelvin–Helmholtz instability (KHI). The jet breakup rate as well as the resulting particle size are important parameters that would largely govern the intensity of a steam explosion in severe reactor accidents. First, a two-dimensional simulation of KHI along the melt-liquid coolant interface was performed using the VOF model in ANSYS Fluent with fine meshes as small as 0.02 mm. The dominant wavelength obtained by FFT analysis of calculated melt volume fractions showed that the fastest growing wavelength from the linear analysis of KHI is seen only at the very early development of the instability, and it increases gradually. Second, a three-dimensional simulation of BLS was performed, and the shapes and sizes of the melt particles were obtained. The particle size distributions from KHI and BLS simulations were compared with COLDJET experimental data of Woods metal and water, and it showed that the finer drops of one millimeter or smaller are produced by Kelvin–Helmholtz instability, and the drops of a few millimeters in diameter are mainly produced by boundary layer stripping.https://www.mdpi.com/1996-1073/15/20/7517fuel–coolant interactionjet breakupKelvin–Helmholtz instabilityboundary layer stripping
spellingShingle Min-Soo Kim
Kwang-Hyun Bang
Numerical Simulation of Kelvin–Helmholtz Instability and Boundary Layer Stripping for an Interpretation of Melt Jet Breakup Mechanisms
Energies
fuel–coolant interaction
jet breakup
Kelvin–Helmholtz instability
boundary layer stripping
title Numerical Simulation of Kelvin–Helmholtz Instability and Boundary Layer Stripping for an Interpretation of Melt Jet Breakup Mechanisms
title_full Numerical Simulation of Kelvin–Helmholtz Instability and Boundary Layer Stripping for an Interpretation of Melt Jet Breakup Mechanisms
title_fullStr Numerical Simulation of Kelvin–Helmholtz Instability and Boundary Layer Stripping for an Interpretation of Melt Jet Breakup Mechanisms
title_full_unstemmed Numerical Simulation of Kelvin–Helmholtz Instability and Boundary Layer Stripping for an Interpretation of Melt Jet Breakup Mechanisms
title_short Numerical Simulation of Kelvin–Helmholtz Instability and Boundary Layer Stripping for an Interpretation of Melt Jet Breakup Mechanisms
title_sort numerical simulation of kelvin helmholtz instability and boundary layer stripping for an interpretation of melt jet breakup mechanisms
topic fuel–coolant interaction
jet breakup
Kelvin–Helmholtz instability
boundary layer stripping
url https://www.mdpi.com/1996-1073/15/20/7517
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AT kwanghyunbang numericalsimulationofkelvinhelmholtzinstabilityandboundarylayerstrippingforaninterpretationofmeltjetbreakupmechanisms