The design and analysis of impellers for mixing applications such as stirred tank reactors (STR) have significant application in many engineering processes. In particular, the evaluation of the turbulent flow boundary conditions immediately around a model impeller has been examined using flow visualization, laser Doppler anemometry (LDA) and particle image velocimetry (PIV). Mean and fluctuating velocities are presented for all three velocity components. Good agreement between LDA and PIV measurements was obtained once an optimized PIV arrangement was defined. Turbulence parameters such as kinetic energy, dissipation, and length scales are estimated from the measurements. Several approaches to evaluating dissipation were used. Triggered PIV measurements were used to evaluate the variation in radial and tangential velocities in the entire planes above and below the impeller at constant axial distances. The size and orientation of the vortices shed from the impeller blade tips and the corresponding regions of high kinetic energy and dissipation indicate the importance of these structures in mixing.

1.
LaFontaine
,
R. F.
, and
Shepherd
,
I. C.
,
1996
, “
Particle Image Velocimetry Applied to a Stirred Vessel
,”
Exp. Therm. Fluid Sci.
,
12
, pp.
256
264
.
2.
Bittorf
,
K. J.
, and
Kresta
,
S. M.
,
2000
, “
Active Volume of Mean Circulation for Stirred Tanks Agitated with Axial Impellers
,”
Chem. Eng. Sci.
,
55
, pp.
1325
1335
.
3.
Hockey
,
R. M.
, and
Nouri
,
J. M.
,
1996
, “
Turbulent Flow in a Baffled Vessel Stirred by a 60° Pitched Blade Impeller
,”
Chem. Eng. Sci.
,
51
, pp.
4405
4421
.
4.
Stoots
,
C. M.
, and
Calabrese
,
R. V.
,
1995
, “
Mean Velocity Field Relative to a Rushton Turbine Blade
,”
AIChE J.
,
41
, pp.
1
11
.
5.
Hill
,
D. F.
,
Sharp
,
K. V.
, and
Adrian
,
R. J.
,
2000
, “
Stereoscopic Particle Image Velocimetry Measurements of the Flow Around a Rushton Turbine
,”
Exp. Fluids
,
29
, pp.
478
485
.
6.
Wu
,
H.
,
Patterson
,
G. K.
, and
vanDoorn
,
M.
,
1989
, “
Distribution of Turbulence Energy Dissipation Rates in a Rushton Turbine Stirred Mixer
,”
Exp. Fluids
,
8
, pp.
153
160
.
7.
Ali
,
A. M.
,
Yuan
,
H.
,
Dickey
,
D.
, and
Tatterson
,
G. B.
,
1981
, “
Liquid Dispersion Mechanisms in Agitated Tanks: Part I. Pitched Blade Turbine
,”
Chem. Eng. Comm.
,
10
, pp.
205
214
.
8.
Chang
,
T. P. K.
,
Sheu
,
Y. H. E.
,
Tatterson
,
G. B.
, and
Dickey
,
D. S.
,
1981
, “
Liquid Dispersion Mechanisms in Agitated Tanks: Part II. Straight Blades and Disc Style Turbines
,”
Chem. Eng. Comm.
,
10
, pp.
215
222
.
9.
Rao
,
M. A.
, and
Broadkey
,
R. S.
,
1972
, “
Continuous Flow Stirred Tank Turbulence Parameters in the Impeller Stream
,”
Chem. Eng. Sci.
,
27
, pp.
137
156
.
10.
Kresta
,
S. M.
, and
Wood
,
P. E.
,
1993
, “
The Flow Field Produced by a Pitched Blade Turbine: Characterization of the Turbulence and Estimation of the Dissipation Rate
,”
Chem. Eng. Sci.
,
48
, pp.
1761
1774
.
11.
Kresta
,
S. M.
,
1998
, “
Turbulence in Stirred Tanks: Anisotropic, Approximate, and Applied
,”
Can. J. Chem. Eng.
,
76
, pp.
563
576
.
12.
Sheng
,
J.
,
Meng
,
H.
, and
Fox
,
R. O.
,
1998
, “
Validation of CFD Simulations of a Stirred Tank Using Particle Image Velocimetry Data
,”
Can. J. Chem. Eng.
,
76
, pp.
611
625
.
13.
Pereira
,
J. C. F.
, and
Sousa
,
J. M. M.
,
1995
, “
Experimental and Numerical Investigation of Flow Oscillations in a Rectangular Cavity
,”
ASME J. Fluids Eng.
,
117
, pp.
68
74
.
14.
Johnson, D. A., 1988, “An Experimental and Numerical Investigation of Turbulent Recirculating Flow Within a Cavity With an Inlet Wall Jet,” M. Eng. thesis, McMaster University, Hamilton, Canada.
15.
Prasad
,
A. K.
,
Adrian
,
R. J.
,
Landreth
,
C. C.
, and
Offutt
,
P. W.
,
1992
, “
Effect of Resolution on the Speed and Accuracy of Particle Image Velocimetry Interrogation
,”
Exp. Fluids
,
13
, pp.
105
116
.
16.
Guezennec
,
Y. G.
, and
Kiritsis
,
N.
,
1990
, “
Statistical Investigation of Errors in Particle Image Velocimetry
,”
Exp. Fluids
,
10
, pp.
138
146
.
17.
Westerweel
,
J.
,
1997
, “
Fundamentals of Digital Particle Image Velocimetry
,”
Meas. Sci. Technol.
,
8
, pp.
1379
1392
.
18.
Zhou
,
G.
, and
Kresta
,
S. M.
,
1996
, “
Distribution of Energy Between Convective and Turbulent Flow for Three Frequently Used Impellers
,”
Trans. Inst. Chem. Eng., Part A
,
74
, pp.
379
389
.
19.
Ranade
,
V. V.
, and
Joshi
,
J. B.
,
1989
, “
Flow Generated by Pitched Blade Turbines I: Measurements Using Laser Doppler Anemometer
,”
Chem. Eng. Comm.
,
81
, pp.
197
224
.
20.
Wu
,
H.
, and
Patterson
,
G. K.
,
1989
, “
Laser Doppler Measurements of Turbulent Flow Parameters in a Stirred Mixer
,”
Chem. Eng. Sci.
,
44
, pp.
2207
2221
.
21.
Yianneskis
,
M.
,
Popiolek
,
Z.
, and
Whitelaw
,
J. H.
,
1987
, “
An Experimental Study of the Steady and Unsteady Flow Characteristics of Stirred Reactors
,”
J. Fluid Mech.
,
175
, pp.
537
555
.
22.
Hinze, J. O., 1975, Turbulence, McGraw-Hill, NY.
23.
Sharp, K. V., Kim, K. C., and Adrian, R., 2000, “Dissipation Estimation Around a Rushton Turbine Using Particle Image Velocimetry,” Laser Techniques Applied to Fluid Mechanics: selected papers from the 9th Intl. Symp. 1998, Springer-Verlag.
24.
Jaworski
,
Z.
,
Nienow
,
A. W.
, and
Dyster
,
K. N.
,
1996
, “
An LDA Study of the Turbulent Flow Field in a Baffled Vessel Agitated by an Axial, Down-pumping Hydrofoil Impeller
,”
Can. J. Chem. Eng.
,
74
, pp.
3
15
.
25.
Myers
,
K. J.
,
Ward
,
R. W.
, and
Bakker
,
A.
,
1997
, “
A Digital Particle Image Velocimetry Investigation of Flow Field Instabilities of Axial-Flow Impellers
,”
ASME J. Fluids Eng.
,
119
, pp.
623
632
.
26.
Scha¨fer
,
M.
,
Yianneskis
,
M.
,
Wachter
,
P.
, and
Durst
,
F.
,
1998
, “
Trailing Vortices Around a 45° Pitched Blade Impeller
,”
AIChE J.
,
44
, pp.
1233
1246
.
You do not currently have access to this content.