Experimental characterization of secondary atomization at high Ohnesorge numbers

Radhakrishna, V.; Shang, Weixiao; Yao, Longchao; Sojka, Paul E.

doi:10.1016/j.ijmultiphaseflow.2021.103591

Cited by 21 publications

(15 citation statements)

References 20 publications

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“…2009; Radhakrishna et al. 2021). In this condition, because the rapid development of the tail bag consumes much liquid, the swing breakup of the droplet body does not occur, and the front rim is lifted and then shrinks.…”

Section: Resultsmentioning

confidence: 99%

Droplet breakup in airflow with strong shear effect

Wang

Che

2022

J. Fluid Mech.

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The deformation and breakup of droplets in airflows is important in spray and atomisation processes, but the shear effect in non-uniform airflow is rarely reported. In this study, the deformation and breakup of droplets in a shear flow of air is investigated experimentally using high-speed imaging, digital image processing and particle image velocimetry. The results show that in airflow with a strong shear effect, the droplet breakup exhibits unique features due to the uplift and stretching produced by the interaction between the deformed droplet and the shear layer. The breakup process can be divided into three stages according to the droplet morphology and the breakup mechanism, namely the sheet breakup, the swing breakup and the rim breakup stages. Theoretical analysis reveals that the swing breakup is governed by the transverse Rayleigh–Taylor instability. A regime map of the droplet breakup is produced, and the transitions between different regimes are obtained theoretically. The stretching liquid film during the droplet deformation and the fragment size distribution after droplet breakup are analysed quantitatively, and the results show that they are determined by the competition of breakup at different stages affected by the shear. Finally, the effect of the droplet viscosity is investigated, and the viscosity inhibits the droplet breakup in a strong shear airflow.

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Section: Resultsmentioning

confidence: 99%

Droplet breakup in airflow with strong shear effect

Wang

Che

2022

J. Fluid Mech.

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“…Ohnesorge number affects the spray sheet breakup process. 40 Since the Ohnesorge number is large for butanol, their coarse droplets go for secondary atomization whereas for the case of butyl butyrate mostly the atomization occurs near the tip of the nozzle and can be seen in Figures 10 and 11.…”

Section: Breakup Characteristics Of Spray Sheetmentioning

confidence: 99%

Experimental investigation on spray characteristics of Jet A-1 and alternative aviation fuels

Kumar

Karmakar

Kumar

et al. 2021

International Journal of Spray and Combustion Dynamics

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Potential alternative fuels that can mitigate environmental pollution from gas turbine engines (due to steep growth in the aviation sector globally) are getting significant attention. Spray behavior plays a significant role in influencing the combustion performance of such alternative fuels. In the present study, spray characteristics of Kerosene-based fuel (Jet A-1) and alternative aviation fuels such as butyl butyrate, butanol, and their blends with Jet A-1 are investigated using an air-blast atomizer under different atomizing air-to-fuel ratios. Phase Doppler Interferometry has been employed to obtain the droplet size and velocity distribution of various fuels. A high-speed shadowgraphy technique has also been adopted to make a comparison of ligament breakup characteristics and droplet formation of these alternative biofuels with that of Jet A-1. An effort is made to understand how the variation in fuel properties (mainly viscosity) influences atomization. Due to the higher viscosity of butanol, the SMD is higher, and the droplet formation seems to be delayed compared to Jet A-1. In contrast, the lower viscosity of butyl butyrate promotes faster droplet formation. The effects of the blending of these biofuels with Jet A-1 on atomization characteristics are also compared with that of Jet A-1.

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“…When the spherical drop encounters the gas flow, aerodynamic forces cause the drop to deform and break apart into fragments, a process referred to as secondary atomization. [11][12][13][14][15][16][17][18] The Weber number (We) is an essential dimensionless parameter that represents the ratio of disruptive hydrodynamic forces to the stabilizing surface tension force.…”

Section: Introductionmentioning

confidence: 99%

“…The free‐fall of a large raindrop in a gaseous phase can occur in several stages: destabilization, deformation, and ultimate fragmentation. When the spherical drop encounters the gas flow, aerodynamic forces cause the drop to deform and break apart into fragments, a process referred to as secondary atomization 11–18 . The Weber number ( We ) is an essential dimensionless parameter that represents the ratio of disruptive hydrodynamic forces to the stabilizing surface tension force.

italicWe goodbreak= \frac{ρ_{g} u^{2} D_{0}}{σ},

where

ρ_{g}

is the ambient gas density,

u

is the relative velocity between the gas and drop,

D_{0}

is the initial diameter of a liquid drop, and

σ

is the surface tension.…”

Section: Introductionmentioning

confidence: 99%

Drop breakup and entrainment in the updraft

Liu

Wang

et al. 2022

AIChE Journal

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This study aims to investigate the characteristics of gas-liquid countercurrent contact processes. In spray towers or other applications, several drops containing pollutants are entrained by the updraft flue gas, which can easily cause environmental pollution. Traditionally, this drop entrainment phenomenon is alleviated by increasing the diameter of the drops. However, the breakup of a large drop would also cause drop entrainment to become serious, a process referred to as secondary atomization. Herein, we propose the boundary of three drop modes in the updraft: drop falling mode, reverse entrainment mode, and breakup entrainment mode. The critical Weber number (We) is the key dimensionless number marking the beginning of the drop breakup. The ratio of the drag force to gravity and We are proposed as criteria for the drop entrainment.

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Experimental characterization of secondary atomization at high Ohnesorge numbers

Cited by 21 publications

References 20 publications

Droplet breakup in airflow with strong shear effect

Droplet breakup in airflow with strong shear effect

Experimental investigation on spray characteristics of Jet A-1 and alternative aviation fuels

Drop breakup and entrainment in the updraft

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