Breakup and atomization characteristics of mono-dispersed diesel droplets in a cross-flow air stream

Park, Sung Wook; Kim, Sayop; Lee, Chang Sik

doi:10.1016/j.ijmultiphaseflow.2006.02.019

Cited by 52 publications

(17 citation statements)

References 15 publications

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“…It was concluded that the breakup process in the three breakup regimes is independent of the Re number and it is only a function of the We number for the range of Oh and ε examined. The work of [7,8] investigated the microscopic (droplet scale) and macroscopic (spray scale) breakup characteristics of Diesel droplets by introducing monodispersed droplets into a gas stream ejected from a nozzle. They examined We numbers from 4.3 up to 383 in three breakup regimes (vibrational, bag and sheet-thinning) and produced images of the breakup process and graphs for the droplet mean velocities and diameters.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of the aerodynamic breakup of diesel droplets under various gas pressures

Stefanitsis

Malgarinos

Strotos

et al. 2017

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

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The present study investigates numerically the aerodynamic breakup of Diesel droplets for a wide range of ambient pressures encountered in engineering applications relevant to oil burners and internal combustion engines. The numerical model solves the Navier-Stokes equations coupled with the Volume of Fluid (VOF) methodology utilized for capturing the interface between the liquid and the surrounding gas. An adaptive local grid refinement technique is used to increase the accuracy of the numerical results around the interface. The Weber (We) numbers examined are in the range of 14 to 279 which correspond to bag, multimode and sheet-thinning breakup regimes. Model results are initially compared against published experimental data and show a good agreement in predicting the drop deformation and the different breakup modes. The predicted breakup initiation times for all cases lie within the theoretical limits given by empirical correlations based on the We number. Following the model validation, the effect of density ratio on the breakup process is examined by varying the gas density (or equivalently the ambient pressure), while the We number is kept almost constant equal to 270; ambient gas pressure varies from 1 up to 146bar and the corresponding density ratios (ε) range from 700 down to 5. Results indicate that the predicted breakup mode of sheet-thinning remains unchanged for changing the density ratio. Useful information about the instantaneous drag coefficient (Cd) and surface area as functions of the selected non-dimensional time is given. It is shown that the density ratio is affecting the drag coefficient, in agreement with previous numerical studies. KeywordsDroplet breakup, Diesel, VOF, density ratio, breakup initiation time. IntroductionDroplet motion, deformation and breakup are observed in a wide variety of engineering applications such as in the injection systems of oil burners and internal combustion engines. Droplet deformation and subsequent breakup are caused by aerodynamic forces exerted on the drop by the surrounding gas, while surface tension and viscosity of the drop hinder deformation and tend to restore it to a spherical shape. The non-dimensional numbers that account for these effects are the Weber (We), Ohnesorge (Oh) and Reynolds (Re) numbers as well as the density (ε) and viscosity (N) ratios of the two phases [1]; the timescale used to non-dimensionalise the time is the shear breakup timescale [2]. For low Oh numbers (Oh<0.1) the droplet breakup is mainly controlled by the We number and according to [1] four different breakup regimes are observed as the We number increases. For We numbers in the range of 11 up to 35 the bag breakup mode is encountered during which the drop deforms into a bag resembling shape. As the We number is further increased up to 80, the multimode regime starts to appear which is essentially a combination of the bag and sheet-thinning modes. In the sheet-thinning breakup mode (80

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Section: Introductionmentioning

confidence: 99%

Numerical investigation of the aerodynamic breakup of diesel droplets under various gas pressures

Stefanitsis

Malgarinos

Strotos

et al. 2017

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

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“…It is evident that there is more active interaction between the droplets in the dense spray, nearnozzle region of a group-hole nozzle. Hence, coalescence collisions are expected to be more dominant than grazing droplet separations (Park et al, 2006;Lee and Reitz, 2001) at low Weber numbers (i.e., low injection pressure and high ambient pressure). Therefore active interaction between the droplets from group-hole nozzles increase SMD.…”

Section: Validation Of the Gas Jet Superimposition Model And Effect Omentioning

confidence: 99%

A gas jet superposition model for CFD modeling of group-hole nozzle sprays

Park

Reitz

2009

International Journal of Heat and Fluid Flow

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“…Of these techniques; the Phase Doppler Particle Analyzer (PDPA) which has been used extensively for investigating spray characteristics for different liquids [12][13][14][15][16] and for high-pressure common rail [17] and liquid-liquid coaxial swirl injectors [18][19], in addition to velocity gradients [20][21], and transient atomization [22]. Mie Scattering is another laser technique that has been used by [23][24][25][26][27] to investigate the characteristics of sprays generated by flash-boiling, pneumatic atomization, slit, piezo-electric, and port fuel injectors respectively.…”

Section: Introductionmentioning

confidence: 99%

“…Mie Scattering is another laser technique that has been used by [23][24][25][26][27] to investigate the characteristics of sprays generated by flash-boiling, pneumatic atomization, slit, piezo-electric, and port fuel injectors respectively. While Laser Induced Fluorescence (LIF) was used to visualize spray atomization [28][29], in addition to the Nd:YAG laser [14,21,[30][31][32][33][34][35][36][37] and other laser techniques mentioned in [12,[38][39][40][41][42][43][44][45][46][47][48]. Shadowgraphs are used as well in spray atomization investigations either individually [49][50][51][52] or accompanied by another optical technique such as laser-based techniques [25,28] and high speed camera [53].…”

Section: Introductionmentioning

confidence: 99%

Quantitative spray analysis of diesel fuel and its emulsions using digital image processing

Faik

Zhang

2015

EPJ Web of Conferences

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Abstract. In the present work, an experimental investigation of spray atomization of different liquids has been carried out. An air-assist atomizer operating at low injection pressures valued (4 and 6 bar) has been used to generate sprays of (diesel fuel, 5, 10, and 15% water-emulsified-diesel), respectively. A Photron-SA4 high speed camera has been used for spray imaging at 2000 fps. 20 time intervals (from 5 to 100 ms with 5 ms time difference) are selected for analysis and comparison. Spray macroscopic characteristics (spray penetration, dispersion, cone angle, axial and dispersion velocities) have been extracted by a proposed technique based on image processing using Matlab, where the maximum and minimum (horizontal and vertical) boundaries of the spray are detected, from which the macroscopic spray characteristics are evaluated. The maximum error of this technique is (1.5% for diesel spray) and a little bit higher for its emulsions.

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Breakup and atomization characteristics of mono-dispersed diesel droplets in a cross-flow air stream

Cited by 52 publications

References 15 publications

Numerical investigation of the aerodynamic breakup of diesel droplets under various gas pressures

Numerical investigation of the aerodynamic breakup of diesel droplets under various gas pressures

A gas jet superposition model for CFD modeling of group-hole nozzle sprays

Quantitative spray analysis of diesel fuel and its emulsions using digital image processing

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