A fiber optic reflectometer (FOR) technique featuring a single fiber probe is investigated for its feasibility of measuring the bubble velocity, diameter, and void fraction in a multiphase flow. The method is based on the interference of the scattered signal from the bubble surface with the Fresnel reflection signal from the tip of the optical fiber. Void fraction is obtained with a high accuracy if an appropriate correction is applied to compensate the underestimated measurement value. Velocity information is accurately obtained from the reflected signals before the fiber tip touches the bubble surface so that several factors affecting the traditional dual-tip probes such as blinding, crawling, and drifting effects due to the interaction between the probe and bubbles can be prevented. The coherent signals reflected from both the front and rear ends of a bubble can provide velocity information. Deceleration of rising bubbles and particles due to the presence of the fiber probe is observed when they are very close to the fiber tip. With the residence time obtained, the bubble chord length can be determined by analyzing the coherent signal for velocity determination before the deceleration starts. The bubble diameters are directly obtained from analyzing the signals of the bubbles that contain velocity information. The chord lengths of these bubbles measured by FOR represent the bubble diameters when the bubble shape is spherical or represent the minor axes when the bubble shape is ellipsoidal. The velocity and size of bubbles obtained from the FOR measurements are compared with those obtained simultaneously using a high speed camera.

1.
R.
Lindken
,
L.
Gui
, and
W.
Merzkirch
,
Chem. Eng. Technol.
22
,
202
(
1999
).
2.
N.
Deen
,
J.
Westerweel
, and
E.
Delnoij
,
Chem. Eng. Technol.
25
,
97
(
2002
).
3.
D. -G.
Seol
,
T.
Bhaumik
,
C.
Bergmann
, and
S. A.
Socolofsky
,
J. Eng. Mech.
133
,
665
(
2007
).
4.
Y.
Ryu
,
K. -A.
Chang
, and
H. -J.
Lim
,
Meas. Sci. Technol.
16
,
1945
(
2005
).
5.
D.
Bröder
and
M.
Sommerfeld
,
Meas. Sci. Technol.
18
,
2513
(
2007
).
6.
H.
Kashima
,
N.
Mori
, and
S.
Kakuno
,
Proceedings of the 30th International Conference on Coastal Engineering
(
ASCE
,
San Diego
,
2006
), Vol.
934
.
7.
H.
Chanson
,
Air bubble Entrainment in Free-Surface Turbulent Flow
(
Academic
,
San Diego
,
1996
).
8.
H.
Chanson
and
T.
Brattberg
,
Int. J. Multiphase Flow
26
,
583
(
2000
).
10.
A.
Cartellier
,
Rev. Sci. Instrum.
63
,
5442
(
1992
).
11.
A.
Rinne
and
R.
Loth
,
Exp. Therm. Fluid Sci.
13
,
152
(
1996
).
12.
E.
Barrau
,
N.
Rivière
,
C.
Poupot
, and
A.
Cartellier
,
Int. J. Multiphase Flow
25
,
229
(
1999
).
13.
F.
Murzyn
,
D.
Mouaze
, and
J. R.
Chaplin
,
Int. J. Multiphase Flow
31
,
141
(
2005
).
14.
J.
Rensen
and
V.
Roig
,
Int. J. Multiphase Flow
27
,
1431
(
2001
).
15.
S. L.
Kiambi
,
A. M.
Duquenne
,
A.
Bascoul
, and
H.
Delmas
,
Chem. Eng. Sci.
56
,
6447
(
2001
).
16.
G.
Rojas
and
M. R.
Loewen
,
Exp. Fluids
43
,
895
(
2007
).
17.
H.
Cavalier
,
M.
Thioye
, and
R.
Darrigo
,
Rev. Sci. Instrum.
60
,
1312
(
1989
).
18.
P. M.
Herbert
,
T. A.
Gauthier
,
C. L.
Briens
, and
M. A.
Bergougnou
,
Powder Technol.
80
,
243
(
1994
).
19.
S.
Guet
,
R. V.
Fortunati
,
R. F.
Mudde
, and
G.
Ooms
,
Part. Part. Syst. Charact.
20
,
219
(
2003
).
20.
S.
Luther
,
J.
Rensen
, and
S.
Guet
,
Exp. Fluids
36
,
326
(
2004
).
21.
A.
Cartellier
and
E.
Barrau
,
Int. J. Multiphase Flow
24
,
1265
(
1998
).
22.
J. E.
Juliá
,
W. K.
Harteveld
,
R. F.
Muddie
, and
H. E. A.
Van den Akker
,
Rev. Sci. Instrum.
76
,
035103
(
2005
).
23.
K. -A.
Chang
,
H. -J.
Lim
, and
C. B.
Su
,
Rev. Sci. Instrum.
74
,
3559
(
2003
).
24.
K. -A.
Chang
,
H. -J.
Lim
, and
C. B.
Su
,
Rev. Sci. Instrum.
75
,
286
(
2004
).
25.
R.
Wedin
,
L.
Davoust
,
A.
Cartellier
, and
P.
Byrne
,
Exp. Therm. Fluid Sci.
27
,
685
(
2003
).
26.
T.
Kawaguchi
,
Y.
Akasaka
, and
M.
Maeda
,
Meas. Sci. Technol.
13
,
308
(
2002
).
27.
S.
Dehaeck
,
J. P. A. J.
van Beeck
, and
M. L.
Riethmuller
,
Exp. Fluids
39
,
407
(
2005
).
You do not currently have access to this content.