This paper deals with an experimental study of the breakup characteristics of water emanating from hollow cone hydraulic injector nozzles induced by pressure-swirling. The experiments were conducted using two nozzles with different orifice diameters 0.3 mm and 0.5 mm and injection pressures (0.3–4 MPa) which correspond to Rep = 7000–26 000. Two types of laser diagnostic techniques were utilized: shadowgraph and phase Doppler particle anemometry for a complete study of the atomization process. Measurements that were made in the spray in both axial and radial directions indicate that both velocity and average droplet diameter profiles are highly dependent on the nozzle characteristics, Weber number and Reynolds number. The spatial variation of diameter and velocity arises principally due to primary breakup of liquid films and subsequent secondary breakup of large droplets due to aerodynamic shear. Downstream of the nozzle, coalescence of droplets due to collision was also found to be significant. Different types of liquid film breakup were considered and found to match well with the theory. Secondary breakup due to shear was also studied theoretically and compared to the experimental data. Coalescence probability at different axial and radial locations was computed to explain the experimental results. The spray is subdivided into three zones: near the nozzle, a zone consisting of film and ligament regime, where primary breakup and some secondary breakup take place; a second zone where the secondary breakup process continues, but weakens, and the centrifugal dispersion becomes dominant; and a third zone away from the spray where coalescence is dominant. Each regime has been analyzed in detail, characterized by timescale and Weber number and validated using experimental data.

1.
H.
Shi
and
C.
Kleinstreuer
, “
Simulation and analysis of high-speed droplet spray dynamics
,”
J. Fluids Eng.
129
,
621
633
(
2007
).
2.
A. H.
Lefebvre
,
Atomization and Sprays (Combustion: An International Series)
(
CRC
,
Boca Raton, FL,
1989
).
3.
P. K.
Senecal
,
D. P.
Schmidt
,
I.
Nouar
,
C. J.
Rutland
, and
R. D.
Reitz
, “
Modelling high-speed viscous liquid sheet atomization
,”
Int. J. Multiphase Flow
25
,
1073
1097
(
1999
).
4.
D. P.
Schmidt
,
I.
Nouar
,
P. K.
Senecal
,
J.
Homan
,
C. J.
Rutland
,
J.
Martin
, and
R. D.
Reitz
, “
Pressure-swirl atomization in the near field
,” SAE Paper 1999-01-0496 (
1999
).
5.
A.
Mansour
and
N.
Chigier
, “
Dynamic behavior of liquid sheets
,”
Phys. Fluids
3
,
2971
2980
(
1991
).
6.
G. M.
Faeth
,
L. P.
Hsiang
, and
P. K.
Wu
, “
Structure and breakup properties of sprays
,”
Int. J. Multiphase Flow
21
,
99
127
(
1995
).
7.
S. H.
Park
,
H. J.
Kim
,
H. K.
Suh
, and
C. S.
Lee
, “
Experimental and numerical analysis of spray-atomization characteristics of biodiesel fuel in various fuel and ambient temperatures conditions
,”
Int. J. Heat Fluid Flow
30
,
960
970
(
2009
).
8.
H. J.
Kim
,
H. K.
Suh
,
S. H.
Park
, and
C. S.
Lee
, “
An experimental and numerical investigation of atomization characteristics of biodiesel, dimethyl ether, and biodiesel-ethanol blended fuel
,”
Energy Fuels
22
,
2091
2098
(
2008
).
9.
R.
Payri
,
B.
Tormos
,
F. J.
Salvado
, and
L.
Araneo
, “
Spray droplet velocity characterization for convergent nozzles with three different diameters
,”
Fuel
87
,
3176
3182
(
2008
).
10.
A.
Tratnig
,
G.
Brenn
,
T.
Stirxner
,
P.
Franhauser
,
N.
Laubacher
, and
M.
Stranzinger
, “
Characterization of spray formation from emulsions by pressure-swirl atomizers for spray drying
,”
J. Food Eng.
95
,
126
134
(
2009
).
11.
A.
Aliseda
,
E. J.
Hopfinger
,
J. C.
Lasheras
,
D. M.
Kremer
,
A.
Berchielli
, and
E. K.
Connolly
, “
Atomization of viscous and non-newtonian liquids by a coaxial, high-speed gas jet. Experiments and droplet size modelling
,”
Int. J. Multiphase Flow
34
,
161
175
(
2008
).
12.
M. C.
Butler Ellis
,
C. R.
Tuck
, and
P. C. H.
Miller
, “
Dilute emulsions and their effect on the breakup of the liquid sheet produced by flat-fan spray nozzles
,”
Atomization Sprays
9
,
385
397
(
1999
).
13.
C. D.
Bolszo
,
M.
Rohani
,
A. A.
Narvaez
,
D.
Dunn-Rankin
,
V. G.
McDonell
, and
W. A.
Sirignano
, “
Pressure-swirl atomization of water-in-oil emulsions
,”
Atomization Sprays
20
,
1077
1099
(
2010
).
14.
M.
Ahmed
,
N.
Ashgriz
, and
H. N.
Tran
, “
Break-up length and spreading angle of liquid sheets formed by splash plate nozzles
,”
J. Fluids Eng.
131
,
011306
1
011306
9
(
2009
).
15.
R.
Reitz
and
F. V.
Bracco
, “
Mechanism of atomization of a liquid jet
,”
Phys. Fluids
25
,
1730
1742
(
1982
).
16.
S. P.
Lin
and
R. D.
Reitz
, “
Drop and spray formation from a liquid jet
,”
Annu. Rev. Fluid Mech.
30
,
85
105
(
1998
).
17.
W. A.
Sirignano
and
C.
Mehring
, “
Review of theory of distortion and disintegration of liquid streams
,”
Prog. Energy Combust. Sci.
26
,
609
655
(
2000
).
18.
J. C.
Lasheras
,
E.
Villermaux
, and
E. J.
Hopfinger
, “
Break-up and atomization of a round water jet by a high-speed annular air jet
,”
J. Fluid Mech.
357
,
351
379
(
1998
).
19.
J. C.
Lasheras
and
E. J.
Hopfinger
, “
Liquid jet instability and atomization in a coaxial gas stream
,”
Annu. Rev. Fluid Mech.
32
,
275
308
(
2000
).
20.
C.
Dumouchel
, “
Measurements of breakup length of cylindrical liquid jets. Application to low-pressure car injector
,”
Atomization Sprays
11
,
201
226
(
2001
).
21.
C.
Dumouchel
, “
On the experimental investigation on primary atomization of liquid streams
,”
Exp. Fluids
45
,
371
422
(
2008
).
22.
C.
Dumouchel
,
J.
Cousin
, and
K.
Triballier
, “
On the role of the liquid flow characteristics on low-Weber-number atomization processes
,”
Exp. Fluids
38
,
637
647
(
2005
).
23.
D.
Sivakumar
and
V.
Kulkarni
, “
Regimes of spray formation in gas-centered swirl coaxial atomizers
,”
Exp. Fluids
51
,
587
596
(
2011
).
24.
S.
Wahono
,
D.
Honnery
,
J.
Soria
, and
J.
Ghojel
, “
High speed visualisation of primary break-up of an annular liquid sheet
,”
Exp. Fluids
44
,
451
459
(
2008
).
25.
P.
Walzel
, “
Spraying and atomizing of liquids
,”
Ullmann's Encyclopedia of Industrial Chemistry
(
Wiley
,
2010
)
26.
A.
Lichtarowicz
,
R. K.
Duggins
, and
E.
Markland
, “
Discharge coefficients for incompressible non-cavitating flow through long orifices
,”
J. Mech. Eng. Sci.
7
,
210
219
(
1965
).
27.
L.
Rayleigh
, “
On the instability of jets
,”
Proc. London Math. Soc.
10
,
4
13
(
1879
).
28.
N.
Dombrowski
and
W. R.
Johns
, “
The aerodynamic instability and disintegration of viscous liquid sheets
,”
Chem. Eng. Sci.
18
,
203
214
(
1963
).
29.
C.
Weber
, “
On the breakdown of a liquid jet
,”
Z. Angew. Math. Phys.
11
,
136
159
(
1931
).
30.
D. R.
Guildenbecher
,
C.
Lopez-Rivera
, and
P. E.
Sojka
, “
Secondary atomization
,”
Exp. Fluids
46
,
371
402
(
2009
).
31.
P. J.
O’ Rourke
and
A. A.
Amsden
, “
The TAB method for numerical calculation of spray droplet breakup
,” SAE Technical Paper 872089 (
1987
).
32.
L. P.
Hsiang
and
G. M.
Faeth
, “
Near-limit drop deformation and secondary breakup
,”
Int J. Multiphase Flow
18
,
635
652
(
1992
).
33.
Y. J.
Jiang
,
A.
Umemura
, and
C. K.
Law
, “
An experimental investigation on the collision behavior of hydrocarbon droplets
,”
J. Fluid Mech.
234
,
171
190
(
1992
).
34.
J.
Qian
and
C. K.
Law
, “
Regimes of coalescence and separation in droplet collision
,”
J. Fluid Mech.
331
,
59
80
(
1997
).
You do not currently have access to this content.