Numerical Solution of Deforming Evaporating Droplets at Intermediate Reynolds Numbers

Haywood, R. J.; Renksizbulut, Metin; Raithby, G. D.

doi:10.1080/10407789408955991

Cited by 32 publications

(11 citation statements)

References 23 publications

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“…A disadvantage of the model is its limitation to 2D axisymmetric problems and small deformations. Haywood et al used their model described in [11] to simulate the transient evaporation process of deformed droplets [12]. The model is similar to the one mentioned before and also limited to two-dimensional cases.…”

Section: Introductionmentioning

confidence: 98%

Direct numerical simulation of evaporating droplets

Schlottke

Weigand

2008

Journal of Computational Physics

177

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Section: Introductionmentioning

confidence: 98%

Direct numerical simulation of evaporating droplets

Schlottke

Weigand

2008

Journal of Computational Physics

177

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“…Regarding the coupled problem of droplet breakup and evaporation, this has not yet been studied in detail except in the CFD works of [55][56][57][58][59][60]. Haywood et al [55,56] showed that for droplets under steady or unsteady (oscillatory) deformation, the quasi-steady correlations for Nusselt (Nu) and Sherwood (Sh) numbers are still valid when a volume-equivalent diameter is used, Mao et al [57] showed that the mass transfer from deformed droplets is mainly controlled by the Peclet (Pe) number, while the We number has a small impact only at high Pe numbers. Hase and Weigand [58] studied the effect of droplet deformation on the heat transfer enhancement and they found that this increases due to the oscillatory droplet motion and the increased surface area of the deformed droplets; moreover, the steady-state classical correlations for the Nu number, under-predict the heat transfer at the beginning of the simulation.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic breakup of an n -decane droplet in a high temperature gas environment

Strotos

Malgarinos

Νikolopoulos

et al. 2016

Fuel

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The aerodynamic droplet breakup under the influence of heating and evaporation is studied numerically by solving the Navier-Stokes, energy and transport of species conservation equations; the VOF methodology is utilized in order to capture the liquid-air interphase. The conditions examined refer to an n-decane droplet with Weber numbers in the range 15-90 and gas phase temperatures in the range 600-1000K at atmospheric pressure. To assess the effect of heating, the same cases are also examined under isothermal conditions and assuming constant physical properties of the liquid and surrounding air. Under non-isothermal conditions, the surface tension coefficient decreases due to the droplet heat-up and promotes breakup. This is more evident for the cases of lower Weber number and higher gas phase 2 temperature. The present results are also compared against previously published ones for a more volatile n-heptane droplet and reveal that fuels with a lower volatility are more prone to breakup. A 0-D model accounting for the temporal variation of the heat/mass transfer numbers is proposed, able to predict with sufficient accuracy the thermal behavior of the deformed droplet.

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“…The presented work is carried out with the open-source platform OpenFOAM™ [21], coupling mass, momentum, energy and species between the phases and closing the transient RANS transport equations with the standard k-ε turbulence model. The work by [22] pointed out that the droplet drag is the most relevant contribution to take into account in the force balance, and [23] reported that the introduction of the deformation from the ideal spherical shape is not significant for the flow conditions studied in this work. Along with the drag, the buoyancy effect is included to ensure the correct representation of the spray momentum in the two directions at low cross flow loads.…”

Section: Numerical Modelingmentioning

confidence: 80%

Low Pressure-Driven Injection Characterization for SCR Applications

Nocivelli¹,

Montenegro²,

Eggenschwiler³

2019

SAE Technical Paper Series

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A queous Urea is a non-toxic and stable ammonia carrier and its injection and mixing represent the basis for the most common de-NOx technology for mobile applications. The reactant feed preparation process is defined by evaporation, thermolysis and hydrolysis of the liquid mixture upstream the Selective Catalytic Reduction reactor, and it is strongly dependent on the interaction between spray and gaseous flow. Low-pressure driven injectors are the common industrial standard for these applications, and their behavior in almost-ambient pressure cross flows is significantly different from any in-cylinder application. For this reason, two substantially different injectors in terms of geometry and design are experimentally studied, characterizing drop sizes and velocities through Phase Doppler Anemometry (PDA) and liquid mass spatial distribution through Shadow Imaging (SI). The measurements involve the analysis of the spray in quiescent air conditions, gathering information at the closest to the nozzle reliable location. Distilled water and Urea Water Solution are characterized, clearly showing that the spray evolution is only slightly affected by the mixture composition. These experimental findings act as the basis for the construction of a numerical description of liquid injection within the Lagrangian tracking framework inside 3D finite volume CFD simulations. A robust injection model is defined, pointing out the singularities of the system and identifying the most critical aspects. The proposed model is built on the direct definition of a droplet diameter distribution, putting particular attention in the droplet-to-parcel ratio definition. One of the two injectors is taken as the input and the other one, which shows a considerable different design and spray pattern is used as a test for the modeling approach. The simulation setup is then assessed in cross-flow conditions and validated on data gathered in a synthetic exhaust gas test bench, where the injectors are installed in an optically accessible chamber, allowing PDA and SI measurements over a wide range of thermal and kinematic cross flow conditions, representative of typical Diesel after-treatment systems. Good agreement with the experimental data is obtained, highlighting how the definition of the initial spray droplet kinematic properties is the key feature in the correct description of a spray for SCR applications, regardless of the Urea mass fraction in the mixture. The evolution of the liquid plume inside a realistic after-treatment channel size geometry shows that most of the momentum of the spray is carried by the largest droplets, which are the ones to be correctly described to address important issues in the Urea Water Solution dosing; these are responsible for the excessive wall impingement and subsequent formation of solid deposits. Specific care is applied in the definition of a reasonable CFD framework, determining mesh sizes and sub-model setups able to fulfill affordable computational costs, according to the current industrial standards.

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Numerical Solution of Deforming Evaporating Droplets at Intermediate Reynolds Numbers

Cited by 32 publications

References 23 publications

Direct numerical simulation of evaporating droplets

Direct numerical simulation of evaporating droplets

Aerodynamic breakup of an n -decane droplet in a high temperature gas environment

Low Pressure-Driven Injection Characterization for SCR Applications

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