Comparison of droplet evaporation models for a turbulent, non-swirling jet flame with a polydisperse droplet distribution

Noh, D.; Gallot-Lavallée, Simon; Jones, W.P.; Navarro‐Martinez, S.

doi:10.1016/j.combustflame.2018.04.018

Cited by 38 publications

(29 citation statements)

References 55 publications

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“…A turbulent n-heptane spray jet, issuing from a central nozzle surrounded by an annular turbulent non-swirling jet, is considered in this work. The set-up belongs to the Coria Rouen Spray Burner (CRSB) database [21], [25], [24], [13]. This case is suitable for validation because the boundary conditions are well characterized and measurements of droplet fields and gas velocity are available.…”

Section: Experimental Set-upmentioning

confidence: 99%

LES Study of a Turbulent Spray Jet: Mesh Sensitivity, Mesh-Parcels Interaction and Injection Methodology

D'Ausilio

Stanković

Merci

2019

Flow Turbulence Combust

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This study focuses on Large Eddy Simulations (LES) in the Eulerian-Lagrangian framework of turbulent spray jets. The choice of the numerical grid relates both to turbulence level description and parcels-grid cells interaction. The objective of the present work is to determine a case setup capable of predicting flow fields of a turbulent n-heptane spray jet for which a set of experimental data in non-reactive conditions (isothermal) is available [21]. The study first focuses on the LES grid, based on simulation with only gas phase, and subsequently on the choice of the suitable number of parcels to describe the spray. The droplets behavior is analyzed using the particle Stokes number at different axial locations. Furthermore, a variation in the existing injection methodology, as available in OpenFOAM R , reveals a beneficial impact on the prediction of the experimental data.

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Section: Experimental Set-upmentioning

confidence: 99%

LES Study of a Turbulent Spray Jet: Mesh Sensitivity, Mesh-Parcels Interaction and Injection Methodology

D'Ausilio

Stanković

Merci

2019

Flow Turbulence Combust

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“…It should be noted that the correction factors for evaporation and nonlinear drag used in Equation (14) involving B and Re a , and the correction factors involving λ, introduced in Equations (18) and (19) to account for the internal circulation of the ellipsoidal droplets, are identical to those used for a spherical particles. In the absence of a rigorous analysis for nonlinear drag or liquid ellipsoids, the expressions given in Equations (14), (18) and (19) are expected to be reasonable approximations for high values of λ and/or slightly deformed spheres. The low aspect ratio asymptotes of Equations (18) and (19) reduce to the Stokes drag for a spherical droplet.…”

Section: Nonlinear Hydrodynamic Dragmentioning

confidence: 99%

“…In the absence of a rigorous analysis for nonlinear drag or liquid ellipsoids, the expressions given in Equations (14), (18) and (19) are expected to be reasonable approximations for high values of λ and/or slightly deformed spheres. The low aspect ratio asymptotes of Equations (18) and (19) reduce to the Stokes drag for a spherical droplet. The effective drag coefficient vector with components along the ellipsoid three principal directions are given as…”

Section: Nonlinear Hydrodynamic Dragmentioning

confidence: 99%

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A Model for Fuel Spray Formation with Atomizing Air

Schmidt

Kvasnak

Ahmadi

2019

Fluids

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The formation of a liquid spray emanating from a nozzle in the presence of atomizing air was studied using a computational model approach that accounted for the deformation and break up of droplets. Particular attention was given to the formation of sprays under non-swirling flow conditions. The instantaneous fluctuating fluid velocity and velocity gradient components were evaluated with the use of a probability density function (PDF)-based Langevin equation. Motions of atomized fuel droplets were analyzed, and ensemble and time averaging were used for evaluating the statistical properties of the spray. Effects of shape change of droplets, and their breakup, as well as evaporation, were included in the model. The simulation results showed that the mean-square fluctuation velocities of the droplets vary significantly with their size and shape. Furthermore, the mean-square fluctuation velocities of the evaporating droplet differed somewhat from non-evaporating droplets. Droplet turbulence diffusivities, however, were found to be close to the diffusivity of fluid point particles. The droplet velocity, concentration, and size of the simulated spray were compared with the experimental data and reasonable agreement was found. Fluids 2019, 4, 20 2 of 17 Earlier, McDonell and Samuelsen [22] provided experimental data on droplet size and velocity distributions in a simplex atomizer. Kvasnak et al. [8] examined the formation of liquid sprays in the absence of atomizing air. Their analysis included effects of primary breakup for liquid ellipsoidal droplets based on the Taylor Analogy Breakup (TAB) model developed by O'Rourke and Amsden [23], and later modified by Ibrahim [24], and Kvasnak and Ahmadi [25]. Recent reviews of the spray simulation and breakup methods were presented by Jenny et al. [5].This work was concerned with understanding the effects of droplet deformation, breakup, and evaporation on the dispersion of deforming ellipsoidal spray droplets in turbulent fuel injector flow fields with atomizing air, with a focus towards practical applications. The other goal was to develop a computational tool for the simulation of practical liquid spray fuel injectors. Kvasnak et al. [8] described a detailed numerical procedure for generating ensembles of simultaneous sample particle trajectories for estimating particle velocity and dispersion statistics. The presented study showed that, in many cases of practical importance to fuel injectors with atomizing air, the deformation time scale of the fuel droplets was comparable with their evaporation time scale. The droplet nonsphericity was also found to be an important factor for modeling the fuel injector performance. The simulation results were compared with the experimental data of McDonell and Samuelsen [22] for a simplex atomizer with atomizing air, where qualitative agreement was found.

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“…The LES-DCMC model is employed to simulate a spray jet flame recently studied experimentally [33,34,35]. This test flame has already been simu-65 lated using: LES with the Thickened Flame Model in the limit of a resolved flame [33], LES with the Stochastic Fields Method [36], LES with Filtered Tabulated Chemistry [37] and RANS with Flamelet Generated Manifolds [38].…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of a spray jet flame using Doubly Conditional Moment Closure

Sitte

Mastorakos

2019

Combustion and Flame

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A spray jet flame is modelled using Large Eddy Simulation (LES) with Doubly Conditional Moment Closure (DCMC). Since turbulent spray flames may include multiple combustion modes, the DCMC model uses both mixture fraction and reaction progress variable as conditioning variables. Conditional spray terms were included in the DCMC model to consider the coupling between evaporation and the flame structure. In the case of spatial homogeneity and in the limit of negligible mixture fraction scalar dissipation rate (SDR), the DCMC equation is shown to reproduce the flame structure of freely propagating laminar flames. For the spray jet flame, a good agreement between the simulation results and the experiments is achieved, in terms of the spray statistics, as well as the instantaneous and mean flame shape. The simulation shows important differences in the flame structure between the turbulent inner and the quasilaminar outer flame branch. The doubly-conditional parametrisation appears to be advantageous for resolving small scale effects related to droplet evaporation. Analysis of the DCMC equation suggests that the behaviour of the flame at its anchoring point is strongly influenced by non-premixed burning modes. The solution appears to be weakly affected by terms of convective transport in the DCMC equation, but significant spatial variations and temporal fluctuations of the conditional reaction rate, around 10 % of the time-based mean, persist. the effect of temperature inhomogeneity on ignition [24] and have so far demonstrated a great potential of the modelling approach for predicting complex, transient combustion phenomena. To the knowledge of the authors, the only simulation of a lab-scale flame using DCMC, coupled with a Reynolds-Averaged Navier Stokes (RANS) computation, has been performed by Sitte and Mas-50 torakos [25]. From a broader perspective, the strategy of double-conditioning has also been recently employed in the CMC-related modelling approach of Conditional Source-term Estimation (CSE) [26].In this work, we present an application of the LES-DCMC approach, based on mixture fraction and reaction progress variable as conditioning variables. 55This allows parametrisation of the whole range from non-premixed to fully premixed flames. Moreover, the effect of liquid droplet evaporation on the flame structure is considered by modelling the spray terms in conditional space. Inclusion of conditional evaporation terms in the model equation is challenging and

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Comparison of droplet evaporation models for a turbulent, non-swirling jet flame with a polydisperse droplet distribution

Cited by 38 publications

References 55 publications

LES Study of a Turbulent Spray Jet: Mesh Sensitivity, Mesh-Parcels Interaction and Injection Methodology

LES Study of a Turbulent Spray Jet: Mesh Sensitivity, Mesh-Parcels Interaction and Injection Methodology

A Model for Fuel Spray Formation with Atomizing Air

Large Eddy Simulation of a spray jet flame using Doubly Conditional Moment Closure

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