Large eddy simulation of spray atomization with a probability density function method

Navarro‐Martinez, S.

doi:10.1016/j.ijmultiphaseflow.2014.02.013

Cited by 50 publications

(44 citation statements)

References 75 publications

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“…For a distance up to 200D, two regions of this decrease can be identified which correspond to different slopes in the graph in figure 4-b. The same trends are observed in other numerical works (see in [20]). The bandwidth of these regions is affected by the thermophysical properties and is expected to differ for cryogenic releases and non-evaporating jets.…”

Section: Resultssupporting

confidence: 90%

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Numerical simulation of superheated jets using an Eulerian method.

Lyras¹,

Dembele²,

Vendra

et al. 2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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Flash boiling is the rapid phase change of a pressurised fluid that emerges in ambient conditions below its vapour pressure. Flashing can occur either inside or outside the nozzle depending on the local pressure and geometry and the bubble formation leads to interfacial interactions that eventually influence the emerging spray. Lagrangian methods which exist in literature to simulate the flash atomisation and inter-phase heat transfer employ many simplifying assumptions. Typically, sub-models used for the break-up, collisions and evaporation introduce an extensive empiricism that might result in unrealistic predictions for cases like flashing. In this study, a fully Eulerian approach is selected employing the Σ − Y model proposed by Vallet and Borghi. The model tracks liquid structures of any shape and computes the spray characteristics comprising a modified version for the transport equation of the surface density. The main goal of this study is to investigate the performance of this model in flash boiling liquids using the Homogeneous Relaxation Model (HRM) developed by Downar-Zapolski, a model capable of capturing the heat transfer under sudden depressurisation conditions accounting for the non-equilibrium vapour generation. The model in this present study considers that the instantaneous quality would relax to the equilibrium value over a given timescale which is calculated using the flow field values. A segregated approach linking the HRM and Σ − Y is implemented in a compressible formulation in an attempt to quantify the effects of flash boiling in the spray dynamics. The developed model is naturally implemented in RANS in a dedicated solver HRMSonicELSAFoam. Results from simulations of two-phase jets of different subcooled fluids through sharp-edged orifices show that the proposed approach can accurately simulate the primary atomisation and give reliable predictions for the droplet sizes and distribution. Strong effects of the flashing and turbulent mixing on the jet are demonstrated. The model is tested for turbulent flows within small nozzles and was developed within the open source code OpenFOAM. KeywordsFlash-boiling, atomisation, ELSA model. IntroductionFlashing jets occur when a high-pressure liquid flowing through a nozzle or an orifice is suddenly exposed to a low-pressure environment, becoming superheated if it is not already so. Flashing is characterised by a rapid phase change along the jet and bubble nucleation within the liquid core that influences the spray formation [1,2]. Flashing is very important in safety studies in cases of accidental releases of a liquefied flammable gas through a small crack in the pipeline system. In the aerosol industry it can be used to control nucleation having the advantage of producing sprays with very fine droplets within small domains [3]. In its dense part, the two-phase jet might appear in different forms like bubbly, slug or annular and the nucleation is possible to start upstream of the orifice (a process generally termed internal flashing) or at ...

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Section: Resultssupporting

confidence: 90%

“…In finite volume methods, the volume is the control volume as shown in figure 1. The ELSA model has been originally developed and validated in RANS and is proven to accurately model the turbulent mixing [15,20]. It has been modified since its first appearance.…”

Section: Mathematical Formulations and Methodsmentioning

confidence: 99%

Numerical simulation of superheated jets using an Eulerian method.

Lyras¹,

Dembele²,

Vendra

et al. 2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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“…(10), on the other hand, is widely used in the context of inertiadominated two-phase flows, such as liquid jets, bubbles and drops, e.g. [58][59][60][61][62]. It is important to note that some studies on film flows use a Weber number defined as the inverse of We as defined in Eq.…”

Section: A Physical Mechanisms and Pertinent Dimensionless Groupsmentioning

confidence: 99%

Self-similarity of solitary waves on inertia-dominated falling liquid films

et al. 2016

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We propose the first consistent scaling of solitary waves on inertia-dominated falling liquid films, which accurately accounts for the driving physical mechanisms and leads to a self-similar characterization of solitary waves. Direct numerical simulations of the entire two-phase system are conducted using a state-of-the-art finite volume framework for interfacial flows in an open domain that was previously validated against experimental film-flow data with excellent agreement. We present a detailed analysis of the wave shape and the dispersion of solitary waves on 34 different water films with Reynolds numbers Re = 20 − 120 and surface tension coefficients σ = 0.0512 − 0.072 N m −1 on substrates with inclination angles β = 19 • − 90 • . Following a detailed analysis of these cases we formulate a consistent characterization of the shape and dispersion of solitary waves, based on a newly proposed scaling derived from the Nusselt flat film solution, that unveils a self-similarity as well as the driving mechanism of solitary waves on gravity-driven liquid films. Our results demonstrate that the shape of solitary waves, i.e. height and asymmetry of the wave, is predominantly influenced by the balance of inertia and surface tension. Furthermore, we find that the dispersion of solitary waves on the inertia-dominated falling liquid films considered in this study is governed by non-linear effects and only driven by inertia, with surface tension and gravity having a negligible influence.

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“…However, it should be noted that many of the numerical works have been performed on the liquid jet in a co-flowing gas stream or liquid injection into a quiescent gas, typically for diesel applications ( Iyer and Abraham, 20 03;Khosla and Crocker, 20 04;Lin et al, 2014;Navarro-Martinez, 2014;Devassy et al, 2015 ). The existing numerical works of the liquid jets in crossflow are limited, and rarely concerned with the supersonic regimes ( Rachner et al, 2002;Balasubramanyam and Chen, 2008;Im et al, 2011 ).…”

Section: Introductionmentioning

confidence: 99%