Nonmonotonic Effects of Aerodynamic Force on Droplet Size of

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Non-monotonic effects of aerodynamic force on droplet size of prefilming air-blast atomization Hui Zhao, Zhao-Wei Wu, Wei-Feng Li, Jian-Liang Xu, and Hai-Feng Liu Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.7b05026 • Publication Date (Web): 17 Jan 2018 Downloaded from http://pubs.acs.org on January 17, 2018

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Industrial & Engineering Chemistry Research

Non-monotonic effects of aerodynamic force on droplet size of prefilming air-blast atomization Hui Zhao1, 2, Zhao-Wei Wu1, Wei-Feng Li1, Jian-Liang Xu1, Hai-Feng Liu1, * 1.

2.

Key Laboratory of Coal Gasification and Energy Chemical Engineering of Ministry of Education, Shanghai Engineering Research Center of Coal Gasification, East China University of Science and Technology, Shanghai 200237, China Laboratory for Turbulence Research in Aerospace and Combustion, Department of Mechanical and Aerospace Engineering, Monash University, VIC 3800, Australia

Abstract: The goal of this investigation is to improve the understanding of the mechanism on prefilming atomization. The coaxial two-fluid prefilming air-blast atomization has two airflows: inner air jet and outer air jet. It is generally believed that droplet size decreases monotonically with increasing gas velocity in air-blast atomization. However, this work shows that in prefilming atomization the droplet size increases with the increase of gas velocity, and then decreases with the increase of gas velocity when the velocity of the other airflow is high. The relationship between two air jets in prefilming air-blast atomization is mutual restriction rather than assistance. To investigate the non-monotonic phenomenon, the modified Kelvin-Helmhotz and Rayleigh-Taylor instability atomization model for the prefilming air-blast nozzle is induced. This study presents the model developed to predict the performance of coaxial atomizers, and the experimental results are consistent with the model estimates. Keywords: Air-blast; Coaxial; Prefilming; Sprays; Atomization; Instability; Nozzle *Corresponding author: E-mail: [email protected]. Tel.: +86-21-64251418. (H.-F. Liu). 1

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1. Introduction

Liquid atomization, the conversion of bulk liquid into a dispersion of small droplets is of importance in nature and many industrial chemical processes such as combustion, gasification, aerospace, spray drying, evaporative cooling, medicine and printing 1, 2. For all of these applications, it is desirable to have an a priori knowledge of the liquid dispersion structure, in particular its features of droplet sizes as a function of fluid velocity, fluid property, nozzle shape, etc. The air-blast atomization process is very complex, involving highly turbulent and convoluted interfaces as well as breakup and coalescence of liquid masses

3, 4

. The spray literature often reports

drop size information via the representative drop diameter. Sauter mean diameter (SMD) is probably the most commonly used mean, which is especially important in calculations where the active surface area is important. Such areas include catalysis and applications in fuel combustion. SMD is defined as the diameter of the droplet that has the same volume/surface area ratio as a particle of interest 5. In this design of prefilming air-blast nozzle, the liquid is first spread into a very thin sheet or film, which is then exposed to air operating at a high velocity causing atomization. By spreading the liquid into a film, the contact area between the liquid and gas increases. Therefore, gas energy is more efficiently transferred to the liquid . The liquid film breakup and atomization processes could be governed by several instability mechanisms, so the breakup morphology and mode of liquid film is interesting and varied

6-12

. The influence of both Kelvin-Helmholtz (KH) and

Rayleigh-Taylor (RT) mechanisms has been shown to be very important 13-16. The KH 2


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mechanism occurs due to difference in velocities across an interface. The RT mechanism occurs in the presence of unfavorable density stratification at an interface in an acceleration field. Rizkalla and Lefebvre

17

find that the viscous effects appear to have stronger

influence on the drop size as the exponent of viscosity is 0.85, whereas that for surface tension is 0.5. Based on energy analysis, Lefebvre

18

derives equation for the

SMD of a nozzle where the liquid velocities are not too high. Above result is later improved by Barreras and Eduardo 19 to include the effects of the kinetic energy of the liquid. Influence of fluid property on the drop size is also researched by Jasuja Knoll and Sojka

20

,

21

. Chin et al. analyze the atomization performance of high liquid

pressure prefilming air-blast nozzle

22

. The solution enhanced dispersion by

supercritical fluids process using a prefilming atomizer is studied by He and Suo 23-25. Recently prefilming air-blast nozzle is one of the most popular atomizers, which has received great attention from many researchers 26-33. It is generally accepted that the aerodynamic force can promote liquid breakup in air-blast atomization, so the droplet size will decrease with the increase of gas velocity. However in the present work, a detailed investigation on effect of inner and outer airflow characteristics on atomization is performed. The experimental results show the non-monotonic effects of aerodynamic force on droplet size of prefilming air-blast atomization. SMD will increase with the increase of gas velocity under certain conditions. This phenomenon not only can help us learn more knowledge on multiphase flows, but also are useful in the design of industrial atomizer. The

3



objective of this study is to provide better understanding of the prefilming atomization process and mechanism, and then obtain the enhanced design methods of air-blast nozzle. The paper is organized as follows. In Part 2, we describe the experimental setup. And the experimental results will be presented in Part 3. Part 4 is devoted to the conclusions. 2. Experimental set-up The coaxial two-fluid prefilming air-blast atomizer geometry is shown schematically in Figure 1, which has three channels: (1) inner round air jet, (2) annular liquid film and (3) outer annular air jet. D1 - D5 are the characteristic diameters of nozzle, respectively. D1 =2.00 mm, D2 =4.24 mm, D3 =9.30 mm,

D4 =11.18 mm, D5 =16.30 mm. (2) water (1) inner air

(3) outer air

D1 D2 D3 D4 D5

Figure 1. Experimental atomizer configuration. Water with density, ρl = 998 kg·m-3, dynamic viscosity, µl = 1.0 × 10-3 kg·m-1s-1, 4


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surface tension, σ = 0.0728 N·m-1 and air with density, ρ g =1.2 kg·m-3, dynamic viscosity, µ g = 1.8 × 10-5 kg·m-1s-1 are used as experimental fluids. The experimental apparatus is sketched in Figure 2, which is similar to our earlier work 26. The gas and liquid velocities are obtained by the rotameter flow meters. Malvern Spraytec laser diffraction system is utilized to measure the droplet sizes. In this test the laser diffraction system is Malvern Spraytec, which is the product of Malvern Instruments Ltd. There is a detailed description on Malvern Spraytec website

(https://www.malvern.com/en/products/product-range/spraytec).

Malvern

Instruments is a leading provider of scientific instrumentation that are used to measure rheology, particle size, particle shape and more. The laser beam is about 6 mm in diameter. The Spraytec covers a size range of measurement from 0.1-2000 microns. The software of Malvern Spraytec have in-built databases that include the refractive index. The measurement is carried out at the horizontal plane at a distance of 680 mm from the orifice of the atomizer, which is similar to our earlier work 26.

5



Figure 2. Flow chart of experiment process. 1-Air blower; 2-Air flow meter; 3-Experimental atomizer; 4-Malvern Spraytec; 5-Spray chamber; 6-Air liquid separator; 7-Induced draft fan; 8-Liquid tank; 9-Pump; 10-Water flow meter 3. Results and discussion Typical SMD experimental results are shown in Figure 3, which reveals the complexity of the spray dynamics. The fit results in Figure 3 will be analyzed in the following part. The droplet size evolves in a non-monotonic manner as different physical mechanisms. Here u1 is the velocity of inner air jet, u2 is the velocity of water, and u3 is the velocity of outer air jet. As Figure 3(a) demonstrates, SMD increases with the increase of u3 under the fixed value of high u1 , and then decreases with the increase of u3 . The experimental data reveals the relationship between inner and outer air jet is mutual restriction rather than assistance in air-blast atomization. We can find that when the liquid velocity u2 increases, the non-monotonic phenomenon of SMD disappears gradually in Figure 3. Influence of low-speed airflow on liquid film is little. This is a direct consequence of the large momentum ratio between liquid and low-speed airflow. In Figure 3d, the flow of water is great. When the gas velocity u3 is smaller than 40 m/s, the atomization of liquid will be very difficult, so there is no data. The relative standard deviation (coefficient of variation) of the data in Figure 3 is 2.4%.

6


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220 Exp Fit u1= 0 m/s u1= 44 m/s u1= 88 m/s u1= 111 m/s u1= 133 m/s u1= 177 m/s

SMD ( m)

180

140

100

60

0

40

80 u3 (m/s)

(a) u2=0.21m/s

(b) u2=0.40m/s

250 Exp Fit u1= 0 m/s u1= 44 m/s u1= 88 m/s u1= 133 m/s u1= 177 m/s

200 SMD ( m)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


150

100 0

40

80

120

u3 (m/s)

(c) u2=1.03m/s

(d) u2=1.55m/s

Figure 3. SMD results at different fluid velocities.

Figure 4. Sketch of velocity profile of liquid film boundary layer. The aerodynamic force, gas-liquid velocity difference, induces liquid deformation and breakup. In the coaxial air-blast atomization, two initially parallel jets having different velocities are naturally unstable. Then the boundary layer of 7


120


gas-liquid interface is accelerated by airflow. So if there are two different air jets located on both sides of the liquid film, two different boundary layers of gas-liquid interface will appear: high-speed and low-speed boundary layer as shown in Figure 4. The high-speed boundary layer can be considered as the origin of atomization. However the low-speed boundary layer increases the speed of liquid film, and then decreases the velocity difference between high-speed airflow and liquid film. This is the unfavorable factor in air-blast atomization. In Figure 3, as the gas velocity u3 increases, it discourages the atomization at first. So SMD will increases with the increases of u3. When u3 is big enough to become the dominant force, it will promote the atomization. Then SMD will decreases with the increases of u3. Overall, it shows the non-monotonic phenomenon of SMD in Figure 3. Here the classical Kelvin-Helmhotz and Rayleigh-Taylor instability (KH-RT) atomization model

15, 16, 34

is modified and extended to the prefilming air-blast

atomization of three-channel coaxial nozzle. The instability competition of two boundary layers will decide the final atomization performance as shown in Figure 5.

8


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Figure 5. Sketch of instability competition caused by prefilming air-blast atomization. The wavelength of the primary Kelvin-Helmhotz instability, λKH , is given by the following expression 35, 36

λKH = 2δ

ρl ρg

(1)

where ρl and ρ g are the liquid and gas densities, respectively. And δ is the boundary layer thickness,

δ=

C1bg

(2)

Rebg

where C1 is the coefficient depends on nozzle design

15

, bg is the width of gas

channel, Rebg is Reynolds number of gas channel,

Rebg =

u g bg ρ g

µg

9


(3)


Page 10 of 22

where u g and µ g are the velocity and viscosity of gas, respectively. The wavelength of Rayleigh-Taylor instability is 37

λRT = 2π

3σ a ρl

(4)

where σ is the surface tension, a is the acceleration of liquid, 15 2 1 C D ρ g ( u g − uc ) A C ρ ( u − u ) 2 D g g c a∝ 2 = 2 ρl λKH ρl λKH A

(5)

where CD is the drag coefficient and constant, A is the projected area of liquid windward side, uc is the convective velocity of the gas-liquid boundary layer estimated from stress continuity at the interface is 38, 39

uc =

ρl ulf + ρ g u g

(6)

ρl + ρ g

where ulf is the velocity of liquid film, and ulf is also affected by two airflows. So there is

λRT = C2 ( h2bg )

1/ 2

 ρl   ρg

1/ 4

  

−1/ 4 We −1/ 2 Rebg

(7)

where C2 is the coefficient depends on nozzle design, h2 is the thickness of liquid

ρ g ( u g − uc ) h2 D − D2 film h2 = 3 , We is Weber number defined as We = σ 2 2

15

.

C4 Therefore, approximately assuming there is the expression SMD ∝ λRT , where C4

is the coefficient depends on nozzle design, we can obtain that

 b 1/ 2  ρ SMD g = C3    l h2  h2   ρ g 

1/ 4

  

 −1/ 4 Rebg We −1/ 2   

C4

(8)

where C3 is the coefficient depends on nozzle design. By the competition of two air

10


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jets, the prefilming air-blast atomization results will be decided by the dominant airflow. So the final SMD correlation by fit is given by 0.054    h 1/ 2  ρ 1/ 4  −1/ 4 −1/ 2 0.097 1 − 1.7 m −0.43  1 l ( )  h   ρ  Re1 We1  , 21  SMD   2   g    = min   0.22 h2  h 1/ 2  ρ 1/ 4    0.14 (1 − 0.56m23−0.95 )  3   l  Re3−1/ 4 We3−1/ 2    h2   ρ g        

(9) where m21 is the mass flux ratio between liquid and inner air, m23 is the mass flux ratio between liquid and outer air, h1 is the radius of inner air outlet h1 = D1 / 2 , h3 is the thickness of outer air outlet h3 = are

the

Reynolds

ρ g ( u1 − uc1 ) h2

numbers

2

We1 =

σ

of

u Dρ u hρ D5 − D4 , Re1 = 1 1 g and Re3 = 3 3 g 2 µg µg

inner

and

ρ g ( u3 − uc3 ) h2

outer

air

jet

respectively,

2

and We3 =

σ

are the Weber numbers of inner

and outer air jet respectively. All numbers with two significant digits in equations are the fit constants, they are obtained based on the experimental data of this test. In Equation (9), the "min" means that we chose the SMD from the minimum values of two correlations. The values of correlations can be considered proportional to the maximum stable drop size. The drop when its diameter is larger than the stable drop size, can continue to break up 26. So in the far field of atomizer the drop size will tend to the minimum values of two correlations. The Kelvin-Helmholtz and Rayleigh-Taylor (KH-RT) atomization model is adopted by many literature. The expression in this paper is also from the KH-RT atomization model. Indeed, the spray contains a distribution of drops. So in droplet 11



Page 12 of 22

size modeling, SMD is considered to be proportional to λRT by many researchers. These researchers choose SMD as the characteristic drop mean diameter to describe the large number of drop after atomization 15, 16, 34, 40-42. The film convective velocity of prefilming air-blast atomization is complex, as the liquid velocity is also affected by the other side airflow. Based on Equation (6), the

uc =

convective

velocity

of

ρl u2 + B1 ρ g u3 + B2 ρ g u1 ρl + ρ g

prefilming

air-blast

atomizer

would

be

approximately, where B1 and B2 are the fit

constants of convective velocity from experimental data. So the convective velocities of

uc1 =

two

gas-liquid

boundary

ρl u2 + 12 ρ g u3 + 27 ρ g u1 ρl + ρ g

Equation

(9),

0.097 (1 − 1.7 m

−0.43 21

the

flow

 1/ 2  )  hh1   ρρl  2   g

and uc 3 =

condition

1/ 4

  

−1/ 4 1

Re

layers

−1/ 2 1

We

   

of

can

be

ρl u2 + 0.77 ρ g u1 ρl + ρ g maximum

SMD

0.054

=0.14 (1 − 0.56m23

−0.95

written

as

, respectively. In is

 1/ 2  )  hh3   ρρl  2   g

as

follows:

1/ 4

  

Re

−1/ 4 3

−1/ 2 3

We

   

. The above equation is somewhat complicated. For convenience, the approximate simplified equation could be

1.1 1.7 =1 . m23 m21

Based on Equation (9), we can find that the final SMD result of prefilming air-blast atomization is controlled by the competition of two airflows. The SMD value depends mainly on the leading airflow; however the other weak airflow does not play an active role. The dimensionless SMD / h2 values calculated using this correlation are also plotted against the measured values in Figure 3. Equation (9) agrees well with the experimental results as shown in Figure 6, whose correlation coefficient is

12


0.22

Page 13 of 22

R = 0.98 . Figure 6 contains all the data in Figure 3 (a)-(d).

0.10 Calculated value SMD/h2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


0.08 0.06 0.04 0.02 0.00 0.00

0.02

0.04

0.06

0.08

0.10

Experimental value SMD/h2

Figure 6. Comparison of measured SMD / h2 to SMD / h2 predicted by Eq. (9). Non-monotonicity is also found in the spray system performance of a swirling annular sheet

43

. It indicates that non-monotonic effects of liquid atomization is

common phenomenon. Therefore we believe the experimental results not only help us learn more knowledge on the design of atomizer, but also are useful in industrial and engineering chemistry research. Liquid breakup and atomization is very common in industrial engineering. It is generally believed that droplet size decreases monotonically with increasing gas velocity in air-blast atomization. However, the final SMD correlation shows that in prefilming atomization when the velocity of the other airflow is high, droplet size increases with the increase of gas velocity, and then decreases with the increase of gas velocity. The relationship between two air jets in prefilming air-blast atomization is mutual restriction rather than assistance. Therefore we believe the results of the final SMD correlation not only help us learn more knowledge on some engineering 13



processes, but also are useful in the design and application of atomizer.

4. Conclusions The objective of the present study is to investigate the atomization of coaxial two-fluid prefilming air-blast nozzle. The major conclusions of the study are as follows: In the traditional beliefs of air-blast atomization, SMD decreases monotonically with increasing gas velocity. However this study shows that the relationship between two air jets in prefilming air-blast atomization is mutual restriction rather than assistance. When the velocity of the other airflow is high, SMD increases with the increase of gas velocity, and then decreases with the increase of gas velocity. The non-monotonic experimental result is rooted in the influence of two air jets on the boundary layer of gas-liquid interface. Through analysis of the liquid film instability development and breakup mechanism, we obtain the modified KH-RT atomization model for the prefilming air-blast nozzle. The final SMD correlation 0.054    h 1/ 2  ρ 1/ 4  −1/ 4 −1/ 2 0.097 1 − 1.7 m −0.43  1 l ( )  h   ρ  Re1 We1  , 21  SMD   2   g    = min   0.22 h2  h 1/ 2  ρ 1/ 4    0.14 (1 − 0.56m23−0.95 )  3   l  Re3−1/ 4 We3−1/ 2    h2   ρ g        

agrees well with the experimental results.

Nomenclature Roman Letters A

the projected area of liquid windward side

14


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a

acceleration

B1 , B2

the fit constants of convective velocity from experimental data

bg

the width of gas channel

C1 - C4

the fit constants from experimental data on nozzle design

CD

drag coefficient

D1 - D5

the characteristic diameters of nozzle

h1

the radius of inner air outlet

h2

the thickness of liquid film

h3

the thickness of outer air outlet

m21

the mass flux ratio between liquid and inner air

m23

the mass flux ratio between liquid and outer air

u1

the velocity of inner air jet

u2

the velocity of water

u3

the velocity of outer air jet

uc

the convective velocity of the gas-liquid boundary layer

uc1

the convective velocity of inner gas-liquid boundary layer

uc 3

the convective velocity of outer gas-liquid boundary layer

ulf

the velocity of liquid film

Re1

Reynolds numbers of inner air jet

Re3

Reynolds numbers of outer air jet

Rebg

Reynolds number of gas channel

SMD

Sauter mean diameter

15



We

Weber number

We1

Weber numbers of inner air jet

We3

Weber numbers of outer air jet

Greek Letters

µl

liquid viscosity

µg

gas viscosity

ρl

liquid density

ρg

gas density

σ

surface tension

λKH

the wavelength of the Kelvin-Helmhotz instability

λRT

the wavelength of Rayleigh-Taylor instability

δ

the boundary layer thickness

Acknowledgments This research was supported by the National Natural Science Foundation of China (21506059), the Fundamental Research Funds for the Central Universities (222201717004, 222201717018, and 222201717020), Shanghai Natural Science Foundation (15ZR1409500), and the scholarship from China Scholarship Council.

References (1) Caputo, G.; Adami, R.; Reverchon, E. Analysis of dissolved-gas atomization: supercritical CO2 dissolved in water. Ind. Eng. Chem. Res. 2010, 49, 9454-9461. (2) Kim, S. Y.; Lee, H.; Cho, S.; Park, J. W.; Park, J.; Hwang, J. Size control of chitosan capsules containing insulin for oral drug delivery via a combined

16


Page 16 of 22

Page 17 of 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


process of ionic gelation with electrohydrodynamic atomization. Ind. Eng. Chem. Res. 2011, 50, 13762-13770.

(3) Rezvanpour, A.; Attia, A. B. E.; Wang, C. H. Enhancement of particle collection efficiency in electrohydrodynamic atomization process for pharmaceutical particle fabrication. Ind. Eng. Chem. Res. 2010, 49, 12620-12631. (4) Peng, H.; Wang, N.; Wang, D.; Ling, X. Experimental Study on the Critical Characteristics of Liquid Atomization by a Spinning Disk. Ind. Eng. Chem. Res.

2016, 55, 6175-6185. (5) Nasr, G. G.; Yule, A. J.; Bendig, L. Industrial sprays and atomization: design, analysis and applications; Springer Science & Business Media, 2013.

(6) Carvalho, I. S.; Heitor, M. V. Liquid film break-up in a model of a prefilming airblast nozzle. Exp. Fluids 1998, 24, 408-415. (7) Wahono, S.; Honnery, D.; Soria, J.; Ghojel, J. High-speed visualisation of primary break-up of an annular liquid sheet. Exp. Fluids 2008, 44, 451-459. (8) Duke, D.; Honnery, D.; Soria, J. A cross-correlation velocimetry technique for breakup of an annular liquid sheet. Exp. Fluids 2010, 49, 435-445. (9) Duke, D.; Honnery, D.; Soria, J. Experimental investigation of nonlinear instabilities in annular liquid sheets. J. Fluid Mech. 2012, 691, 594-604. (10) Strasser, W.; Battaglia, F. The effects of pulsation and retraction on non-Newtonian flows in three-stream injector atomization systems. Chem. Eng. J.

2017, 309, 532-544. (11) Zhao, H.; Liu, H. F.; Tian, X. S.; Xu, J. L.; Li, W. F.; Lin, K. F. Outer

17



ligament-mediated spray formation of annular liquid sheet by an inner round air stream. Exp. Fluids 2014, 55, 1793. (12) Zhao, H.; Xu, J. L.; Wu, J. H.; Li, W. F.; Liu, H. F. Breakup morphology of annular liquid sheet with an inner round air stream. Chem. Eng. Sci. 2015, 137, 412-422. (13) Lasheras, J. C.; Hopfinger, E. J. Liquid jet instability and atomization in a coaxial gas stream. Annu. Rev. Fluid Mech. 2000, 32, 275-308. (14) Rajamanickam, K.; Basu, S. Insights into the dynamics of spray-swirl interactions. J. Fluid Mech. 2017, 810, 82-126.

(15) Aliseda, A.; Hopfinger, E. J.; Lasheras, J. C.; Kremer, D. M.; Berchielli, A.; Connolly, E. K. Atomization of viscous and non-Newtonian liquids by a coaxial, high-speed gas jet. Experiments and droplet size modeling. Int. J. Multiphase Flow 2008, 34, 161-175.

(16) Vadivukkarasan, M.; Panchagnula, M. V. Combined Rayleigh-Taylor and Kelvin-Helmholtz instabilities on an annular liquid sheet. J. Fluid Mech. 2017, 812, 152-177.

(17) Rizkalla, A. A.; Lefebvre, A. H. Influence of liquid properties on airblast atomizer spray characteristics. J. Eng. Power 1975, 97, 173-179. (18) Lefebvre, A. H. Energy Considerations in twin-fluid atomization. J. Eng. Gas Turbines Power 1992, 114, 89-96.

(19) Barreras, F.; Lozano, A.; Barroso, J.; Lincheta, E. Experimental characterization of industrial twin-fluid atomizers. Atomization Sprays 2006, 16, 127-146.

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Page 19 of 22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(20) Jasuja, A. K. Atomization of crude and residual fuel oils. ASME J. Eng. Power

1979, 101, 250-258. (21) Knoll, K. E.; Sojka P E. Flat-sheet twin-fluid atomization of high-viscosity fluids. Part I: Newtonian liquids. Atomization Sprays 1992, 2, 17-36. (22) Chin, J. S.; Rizk, N. K.; Razdan, M. K. Effect of inner and outer airflow characteristics on high liquid pressure prefilming airblast atomization. J. Propul. Power 2000, 16, 297-301.

(23) He, W. Z.; Suo, Q. L.; Jiang, Z. H.; Shan A.; Hong H L. Precipitation of ephedrine by SEDS process using a specially designed prefilming atomizer. J. Supercrit. Fluids 2004, 31, 101-110.

(24) Suo, Q. L.; He, W. Z.; Huang, Y. C.; Li, C. P.; Hong, H. L.; Li, Y. X.; Zhu, M. D. Micronization of the natural pigment-bixin by the SEDS process through prefilming atomization. Powder Technol. 2005, 154, 110-115. (25) He, W. Z.; Suo, Q. L.; Hong, H. L.; Li, G. M.; Zhao, X. H.; Li, C. P.; Shan, A. Supercritical antisolvent micronization of natural carotene by the SEDS process through prefilming atomization. Ind. Eng. Chem. Res. 2006, 45, 2108-2115. (26) Liu, H. F.; Gong, X.; Li, W. F.; Wang, F. C.; Yu, Z. H. Prediction of droplet size distribution in sprays of prefilming air-blast atomizers. Chem. Eng. Sci. 2006, 61, 1741-1747. (27) Muller, A.; Koch, R.; Bauer, H. -J.; Hehle, M.; Schafer, O. Performance of prefilming airblast atomizers in unsteady flow conditions. ASME Turbo Expo 2006: Power for Land, Sea, and Air 2006, 337-345.

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(28) Gurubaran, R. K.; Sujith, R. I.; Chakravarthy, S. R. Characterization of a prefilming airblast atomizer in a strong swirl flow field. J. Propul. Power 2008, 24, 1124-1132.

(29) Gepperth, S.; Guildenbecher, D.; Koch, R.; Bauer, H. -J. Pre-filming primary atomization: Experiments and modeling. ILASS-Europe 2010, Brno, Czech Republic 2010, 6-8.

(30) Gepperth, S.; Muller, A.; Koch, R.; Bauer, H. -J. Ligament and droplet characteristics in prefilming airblast atomization. ICLASS, Heidelberg, Germany

2012, 2-6. (31) Gepperth, S.; Koch, R.; Bauer, H. -J. Analysis and comparison of primary droplet characteristics in the near field of a prefilming airblast atomizer. ASME Turbo Expo 2013: Turbine Technical Conference and Exposition 2013, V01AT04A002.

(32) Leboucher, N.; Roger, F.; Carreau, J. L. Atomization characteristics of an annular liquid sheet with inner and outer gas flows. Atomization Sprays 2014, 24, 1065-1088. (33) Fu, Q.; Jia, B.; Yang, L. Stability of a confined swirling annular liquid layer with heat and mass transfer. Int. J. Heat Mass Transfer 2017, 104, 644-649. (34) Varga, C. M.; Lasheras, J. C.; Hopfinger, E. J. Initial breakup of a small-diameter liquid jet by a high-speed gas stream. J. Fluid Mech. 2003, 497, 405-434. (35) Marmottant, P. Atomisation d’un courant liquide dans un courant gazeux; Ph.D. Thesis, Institut National Polytechnique de Grenoble, Grenoble, 2001. (36) Marmottant, P.; Villermaux, E. On spray formation. J. Fluid Mech. 2004, 498,

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73-111. (37) Chandrasekhar, S. Hydrodynamic and Hydromagnetic Stability; Courier Corporation, 1961. (38) Bernal, L. P.; Roshko A. Streamwise vortex structure in plane mixing layers. J. Fluid Mech. 1986, 170, 499-525.

(39) Dimotakis, P. E. Two-dimensional shear-layer entrainment. AIAA J. 1986, 24, 1791-1796. (40) Beale,

J.

C.;

Reitz,

R.

D.

Modeling

spray

atomization

with

the

Kelvin-Helmholtz/Rayleigh-Taylor hybrid model. Atomization Sprays 1999, 9, 623-650. (41) Lasheras, J. C.; Hopfinger, E. J. Liquid jet instability and atomization in a coaxial gas stream. Annu. Rev. Fluid Mech. 2000, 32, 275-308. (42) Lee, C. S.; Park, S. W. An experimental and numerical study on fuel atomization characteristics of high-pressure diesel injection sprays. Fuel 2002, 81, 2417-2423. (43) Panchagnula, M. V.; Sojka, P. E.; Santangelo, P. J. On the three-dimensional instability of a swirling, annular, inviscid liquid sheet subject to unequal gas velocities. Phys. Fluids 1996, 8, 3300-3312.

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TOC For Table of Contents Only

airflow u1

liquid film u2

airflow u3

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Nonmonotonic Effects of Aerodynamic Force on Droplet Size of

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