A numerical study on the in-nozzle cavitating flow and near-field jet breakup of a spirally grooved hole nozzle using a LES-VOF method

Leng, Xianyin; Deng, Yicheng; Guan, Wei; Xie, Weibo; He, Zhixia; Wang, Qian; Yan, Xuesheng; Long, Wuqiang

doi:10.1016/j.fuel.2022.125016

Cited by 16 publications

(6 citation statements)

References 62 publications

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“…The smallest cone still including all liquid structures in the spray chamber is drawn on the images to determine the spray spreading angle. 45 The average value of spray spreading angles in the simulation is almost 31 , which agrees closely with the experimental data. 26 The relative error in average values of spray spreading angle from the experimental and numerical results is below 11.5%.…”

Section: Results and Discussion A Verification Of Numerical Modelssupporting

confidence: 82%

“…In this study, for modeling the unresolved turbulence, the Wall-Adapting Local Eddy-Viscosity (WALE) model is employed, which has also been validated in our previous works in terms of string cavitation behaviors 52 and jet breakup structures. 45 The SGS turbulent closure is defined as…”

Section: B Turbulent Modelmentioning

confidence: 99%

“…Many spray models are based on the Eulerian-Eulerian (E-E) framework, including the homogeneous diffuse-interface method, 12,39,40 Eulerian surface area density (R-Y) model, 41,42 and high resolution sharp interface methods. [18][19][20][43][44][45] The volume of fluid (VoF) model developed by Hirt and Nichols 46 is also very popular. It has been widely used for modeling cavitation developments and downstream primary spray breakup in the injector nozzle.…”

Section: Introductionmentioning

confidence: 99%

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Primary breakup of a jet coupled with vortex-induced string cavitation in a fuel injector nozzle

Guan,

Huang,

et al. 2024

Physics of Fluids

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Fuel jet primary breakup strongly depends on the in-nozzle cavitation phenomena found in the high-pressure fuel injector nozzle. Nevertheless, limited attention has been paid to the mechanism of fuel jet primary breakup induced by in-nozzle vortex-induced string-type cavitation. This study involves simulations of in-nozzle string cavitating flow and simultaneously near-nozzle jet primary breakup process using large eddy simulation and volume of fluid, aiming at revealing the effects of string cavitation on jet primary breakup. The numerical results are in good agreement with experimental data in terms of string cavitation intensity, interfacial topology of jet, and spray spreading angle. The numerical investigations indicate that the external surface of the jet experiences Kelvin–Helmholtz instabilities, which results in the development of circumferential and axial surface waves at the fuel film surface. Subsequently, the fuel film surface undergoes progressive wrinkling, resulting in its breakup into multiple ligaments and large droplets. On the internal side of the jet, back-suction of air caused by negative pressure and its interaction with cavitation vapor at the core of the jet lead to the collapse of vapor bubbles. The resulting pressure waves and micro-jets facilitate the detachment of liquid sheets from the internal surface of the jet. Analysis of the enstrophy transport equation indicates that the driving mechanism behind string cavitation jet breakup further downstream is the baroclinic torque term, which is responsible for the generation of a cascade of smaller vortical structures. This effect dominates over vortex stretching and dilatation terms.

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Section: Results and Discussion A Verification Of Numerical Modelssupporting

confidence: 82%

Section: B Turbulent Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Primary breakup of a jet coupled with vortex-induced string cavitation in a fuel injector nozzle

Guan,

Huang,

et al. 2024

Physics of Fluids

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“…In an unconventional work, Leng et al [39] simulated, using (VOF-LES) method, the multi-phase flow inside and outside the spirally grooved hole (SGH) nozzle to investigate its influence on the behavior of breakup process and cavitating flow characteristics for diesel nozzles. They found that the inner-hole's spiral grooves added more dynamics besides aerodynamic effects for the breakup of liquid jets which in turn led to strong enhancement of the emerging jet breakup and substantially near-field dispersion angle.…”

Section: Introductionmentioning

confidence: 99%

Impact of Surrounding Gas Density on the Turbulent Liquid Jet

et al. 2023

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This numerical study aims to investigate the impact of surrounding gas density on liquid turbulent jet. Incompressible large eddy simulations (LES) with Wall-Adapting Local Eddy-Viscosity (WALE) sub-grid scale model in ANSYS-FLUENT were performed to capture the morphology of the breakup as well as the important flow field characteristics. A volume of fluid (VOF) approach was used to track the unsteady evolution and breakup of the liquid jet. Different variables have been examined to assess this impact. These variables are instantaneous velocity, liquid volume fraction, and turbulent kinetic energy. Also, the centerline values have been investigated to obtain the jet half-width and spray dispersion angle. The jet diameter and exit velocity are 0.2 mm and 100 m/s, respectively. Three different liquid-to-gas density ratios of 54.03, 32.42 and 23.49 are considered, corresponding to ambient gas density of 15, 25 and 34.5 kg/m3, respectively. It has been found that the jet speed and the liquid core length are inversely proportional to the density of the ambient gas. Regarding the liquid core length, it was noted that the effect of gas density on the liquid core length is considerably stronger in the gas density range between 15 - 25 kg/m³ (corresponding to density ratios of 54.03 - 32.42) than that in the range of 25 - 34.5 kg/m³ (corresponding to density ratios of 32.42 - 23.49). The results, also, showed that increasing the gas density leads to an increase in Weber number, which in turn causes a high instability, that makes the breakup initiates closer to the nozzle exit and occurs with higher rate. Likewise, it has been found that the jet width and the spray dispersion angle increase with increasing the gas density. HIGHLIGHTS Spray jets are included in many applications because its important in increasing the heat and mass transfer between the liquid and the surrounding fluid Large eddy simulations (LES) and volume of fluid (VOF) models are used to investigate the characteristics of turbulent liquid jet The investigation was characterized as a function of man variables such as turbulent kinetic energy, liquid potential core, the jet dispersion angle and more The investigation showed that the density of surrounding gas has an influence on the liquid jet characteristics GRAPHICAL ABSTRACT

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“…In an unconventional work, Leng et al [39] simulated, using (VOF-LES) method, the multiphase flow inside and outside the spirally grooved hole (SGH) nozzle to investigate its influence on the behavior of breakup process and cavitating flow characteristics for diesel nozzles. They found that the inner-hole's spiral grooves added more dynamics besides aerodynamic effects for the breakup of liquid jets which in turn led to strong enhancement of the emerging jet breakup and substantially near-field dispersion angle Recently, Abdelsamie and Thévenin [40] , by means of DNS, quantified the impact of shear on evaporation and spray autoignition mechanisms by comparing droplets evolving in a high-speed jet flow or in a nearly quiescent environment.…”

Section: Introductionmentioning

confidence: 99%

Impact of the jet velocity on the turbulent liquid jet

Said,

Abdelsamie,

Emara

et al. 2023

Engineering Research Journal

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This numerical study aims to investigate the impact of jet velocity and nozzle diameter on liquid turbulent jet. Incompressible large eddy simulations (LES) with Wall-Adapting Local Eddy-Viscosity (WALE) sub-grid scale model in ANSYS-FLUENT were performed to capture the morphology of the breakup as well as the important flow field characteristics. A volume of fluid (VOF) approach was used to track the unsteady evolution and breakup of the liquid jet. Different results have been analyzed to assess this impact. These results are instantaneous and timeaveraged axial velocity, liquid volume fraction, and turbulent kinetic energy. The results are represented in contours and centerline-and radial-profiles. The surrounding gas density is 34.5 kg/m 3 . The nozzle exit diameter is 0.05 mm. Three jet exit-velocities of 50 m/s, 100 m/s and 150 m/s are considered. The results showed that the predicted location, where drops and ligaments are first seen, moves away from the nozzle as the jet velocity increases, where this location was computed as 𝑥 = 3.5𝐷, 6.5𝐷 and 7.5𝐷 for Case50, Case100 and Case150, respectively. Also, the predicted location, where surface waves developed from Kelvin-Helmholtz instability are first seen, moves towards the nozzle as the jet velocity increases, where this location was computed as 𝑥 = 1.6𝐷, 1𝐷 𝑎𝑛𝑑 0.5𝐷 for Case50, Case100 and Case150, respectively. Regarding the jet dispersion angle and the liquid core length, it was found that they increase with increasing the jet exit velocity.

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A numerical study on the in-nozzle cavitating flow and near-field jet breakup of a spirally grooved hole nozzle using a LES-VOF method

Cited by 16 publications

References 62 publications

Primary breakup of a jet coupled with vortex-induced string cavitation in a fuel injector nozzle

Primary breakup of a jet coupled with vortex-induced string cavitation in a fuel injector nozzle

Impact of Surrounding Gas Density on the Turbulent Liquid Jet

Impact of the jet velocity on the turbulent liquid jet

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