Numerical Study of Liquid Film Characteristics at Varying Operating Conditions in Prefilmer Airblast Atomizer

Volz, Melanie; Nittel, Lena; Habisreuther, Peter; Zarzalis, Nikolaos

doi:10.1002/cite.201500011

Cited by 4 publications

(4 citation statements)

References 9 publications

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“…In turn, increasing shear intensities result in the reduction of the mean liquid film thickness [12,13] and resulting droplet sizes [2]. However, time dependent fluctuations of the liquid film thickness at the tip of the pre-filming area can occur as a result of the processing conditions applied [14][15][16][17].…”

Section: Alr =mentioning

confidence: 99%

Air-Core–Liquid-Ring (ACLR) Atomization Part II: Influence of Process Parameters on the Stability of Internal Liquid Film Thickness and Resulting Spray Droplet Sizes

et al. 2019

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Air-core–liquid-ring (ACLR) atomization presents a specific type of internal mixing pneumatic atomization. It can be used for disintegration of high viscous feed liquids into small droplets at relatively low gas consumptions. However, the specific principle of ACLR atomization is still under research and no guidelines for process and atomizer design are available. Regarding literature on pre-filming atomizers, it can be hypothesized for ACLR atomization that the liquid film thickness inside the exit orifice of the atomizer, as well as the resulting spray droplet sizes decrease with increasing air-to-liquid ratio (ALR) and decreasing feed viscosity. In this study, the time dependent liquid film thickness inside the exit orifice of the atomizer was predicted by means of computational fluid dynamics (CFD) analysis. Results were compared to high speed video images and correlated to measured spray droplet sizes. In conclusion, the hypothesis could be validated by simulation and experimental data, however, at high viscosity and low ALR, periodic gas core breakups were detected in optical measurements. These breakups could not be predicted in CFD simulations, as the simplification of an incompressible gas phase was applied in order to reduce computational costs and time. Nevertheless, the presented methods show good potential for improvement of atomizer geometry and process design as well as for further investigation of the ACLR atomization principle.

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Section: Alr =mentioning

confidence: 99%

Air-Core–Liquid-Ring (ACLR) Atomization Part II: Influence of Process Parameters on the Stability of Internal Liquid Film Thickness and Resulting Spray Droplet Sizes

et al. 2019

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“…The turbulence is modeled with the k-e turbulence model, which is adapted for two-phase flows. The volume of fluid method and the adapted k-e turbulence model for twophase flows are described in detail in [18].…”

Section: Numerical Modelsmentioning

confidence: 99%

Correlation for the Sauter Mean Diameter of a Prefilmer Airblast Atomizer at Varying Operating Conditions

Volz

Habisreuther

Zarzalis

2016

Chemie Ingenieur Technik

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One of the key factors that affect the combustion performance in gas turbines and therefore the amount of pollutant emission and the efficiency is the atomization quality of the liquid fuel. Often reliable droplet size distributions for combustion simulations are missing. In this work a correlation for the Sauter mean diameter based on energy equilibrium is derived and compared to results from three-dimensional numerical simulation of the atomization of a liquid film and to an empirical correlation from the literature. It is shown that the derived correlation agrees better with the results of the simulations than the empirical correlation.

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“…Hence, some attempts have been made to predict the atomization process numerically from first principles. In the context of prefilming airblast atomization, Euler-Euler [11][12][13] and Lagrange-Lagrange [14] approaches have been developed to resolve the gas-liquid interface. Two-phase simulations at elevated pressure have been conducted using both fully Eulerian methods [12] as well as fully Lagrangian methods [15].…”

Section: Introductionmentioning

confidence: 99%

Close Nozzle Spray Characteristics of a Prefilming Airblast Atomizer

et al. 2019

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The formation of pollutant emissions in jet engines is closely related to the fuel distribution inside the combustor. Hence, the characteristics of the spray formed during primary breakup are of major importance for an accurate prediction of the pollutant emissions. Currently, an Euler–Lagrangian approach for droplet transport in combination with combustion and pollutant formation models is used to predict the pollutant emissions. The missing element for predicting these emissions more accurately is well defined starting conditions for the liquid fuel droplets as they emerge from the fuel nozzle. Recently, it was demonstrated that the primary breakup can be predicted from first principles by the Lagrangian, mesh-free, Smoothed Particle Hydrodynamics (SPH) method. In the present work, 2D Direct Numerical Simulations (DNS) of a planar prefilming airblast atomizer using the SPH method are presented, which capture most of the breakup phenomena known from experiments. Strong links between the ligament breakup and the resulting spray in terms of droplet size, trajectory and velocity are demonstrated. The SPH predictions at elevated pressure conditions resemble quite well the effects observed in experiments. Significant interdependencies between droplet diameter, position and velocity are observed. This encourages to employ such multidimensional interdependence relations as a base for the development of primary atomization models.

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Numerical Study of Liquid Film Characteristics at Varying Operating Conditions in Prefilmer Airblast Atomizer

Cited by 4 publications

References 9 publications

Air-Core–Liquid-Ring (ACLR) Atomization Part II: Influence of Process Parameters on the Stability of Internal Liquid Film Thickness and Resulting Spray Droplet Sizes

Air-Core–Liquid-Ring (ACLR) Atomization Part II: Influence of Process Parameters on the Stability of Internal Liquid Film Thickness and Resulting Spray Droplet Sizes

Correlation for the Sauter Mean Diameter of a Prefilmer Airblast Atomizer at Varying Operating Conditions

Close Nozzle Spray Characteristics of a Prefilming Airblast Atomizer

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