Jet flows are encountered in a variety of industrial applications. Although from the points of view of manufacturing with ease and small spatial requirement it is convenient to use short slit nozzles, most of the available studies deal with turbulent jets issuing from contoured nozzles. In the present work, experiments have been conducted in the moderate Reynolds number range of 250–6250 for a slit jet. Mixing characteristics of slit jets seem to be quite different from those of jets emerging out of contoured nozzles. This is primarily due to the differences in the decay characteristics and the large scale eddy structures generated in the near field, which are functions of the initial momentum thickness. It is evident that, in the range of $250⩽Re⩽6250$, the overall spreading characteristics of the slit jet flow have stronger Reynolds number dependence than those of contoured nozzle jets. In particular, the slit jets exhibit slower mean velocity decay rates and slower half-width growth rates. Normalized power spectra and probability distribution functions are used to assess the spatial evolution and the Reynolds number dependence of jet turbulence. It is seen that the fluctuating components of velocity attain isotropic conditions at a smaller axial distance from the nozzle exit than that required for mean velocity components to become self-similar.

1.
Thomas
,
F. O.
, and
Goldschmidt
,
V. W.
, 1986, “
Structural Characteristics of a Developing Turbulent Planar Jet
,”
J. Fluid Mech.
0022-1120,
163
, pp.
227
256
.
2.
Antonia
,
R. A.
,
Browne
,
L. W. B.
,
Rajagopalan
,
S.
, and
Chambers
,
A. J.
, 1983, “
On the Organized Motion of a Turbulent Plane Jet
,”
J. Fluid Mech.
0022-1120,
134
, pp.
49
66
.
3.
,
G.
, 1965, “
Hotwire Measurements in a Plane Turbulent Jet
,”
ASME J. Appl. Mech.
0021-8936,
32
, pp.
721
734
.
4.
Gutmark
,
E.
, and
Wygnanski
,
I.
, 1976, “
The Planar Turbulent Jet
,”
J. Fluid Mech.
0022-1120,
73
(
3
), pp.
465
495
.
5.
,
L. J. S.
, 1965, “
The Structure of a Self Preserving Turbulent Jet
,”
J. Fluid Mech.
0022-1120,
23
, pp.
31
64
.
6.
Klein
,
M.
,
,
A.
, and
Janicka
,
J.
, 2003, “
Investigation of the Influence of the Reynolds Number on a Plane Jet Using Direct Numerical Simulation
,”
Int. J. Heat Fluid Flow
0142-727X,
24
, pp.
785
794
.
7.
Suyambazhahan
,
S.
,
Das
,
S. K.
, and
Sundararajan
,
T.
, 2004, “
Hydrodynamic and Thermal Oscillations in a Non-Isothermal Laminar Jet
,”
Int. J. Heat Mass Transfer
0017-9310,
47
(
17
), pp.
3957
3969
.
8.
Namer
,
I.
, and
Otugen
,
M. V.
, 1988, “
Velocity Measurements in a Plane Turbulent Air Jet at Moderate Reynolds Numbers
,”
Exp. Fluids
0723-4864,
6
, pp.
387
400
.
9.
Jo
,
S. H.
, and
Kim
,
M. U.
, 2002, “
Hydrodynamic Stability of Two Dimensional Jet Near the Nozzle Exit
,”
JSME Int. J., Ser. B
1340-8054,
45
(
3
), pp.
694
703
.
10.
Hussain
,
A. K. M. F.
, and
Clark
,
A. R.
, 1977, “
Upstream Influence on the Near Field of a Plane Turbulent Jet
,”
Phys. Fluids
0031-9171,
20
(
9
), pp.
1416
1426
.
11.
Brunn
,
H. H
, 1995,
Hotwire Anemometry
,
Oxford University Press
,
New York
.
12.
Fujita
,
H.
, and
Kovasznay
,
S. G.
, 1968, “
Measurement of Reynolds Stress by a Single Rotated Hot Wire Anemometer
,”
Rev. Sci. Instrum.
0034-6748,
39
(
9
), pp.
1351
1355
.
13.
Moffat
,
R. J.
, 1985, “
Using Uncertainty Analysis in the Planning of an Experiment
,”
ASME J. Fluids Eng.
0098-2202,
107
, pp.
173
182
.
14.
Krothapalli
,
A.
,
Banganoff
,
D.
, and
Karamcheti
,
K.
, 1981, “
On the Mixing of Rectangular Jet
,”
J. Fluid Mech.
0022-1120,
107
, pp.
201
220
.
15.
Gutmark
,
E.
, and
Ho
,
C. M.
, 1983, “
Preferred Modes and the Spreading Rates of Jets
,”
Phys. Fluids
0031-9171,
26
(
10
), pp.
2932
2938
.
16.
Townsend
,
A. A.
, 1976,
The Structure of Turbulent Free Shear Flow
, 1976,
Cambridge University Press
,
Cambridge, England
.
17.
George
,
W. K.
, 2004, “
Role of Initial Conditions in Establishing Flow Conditions
,”
AIAA J.
0001-1452,
42
(
3
), pp.
438
446
.
18.
Bashir
,
J.
, 1973, “
Experimental Study of the Turbulent Structure and Heat Transfer of a Two Dimensional Heated Jet
,” Ph.D. thesis, University of Colarado, Boulder, CO.
19.
Bashir
,
J.
, and
Uberoi
,
M. S.
, 1975, “
Experiments on Turbulent Structure and Heat Transfer in a Two Dimensional Jet
,”
Phys. Fluids
0031-9171,
18
(
4
), pp.
405
410
.
20.
James
,
J. F.
, and
Lafayette
,
V.
, 1969, “
Virtual Origins of a Plane Turbulent Jet
,”
AIAA J.
0001-1452,
7
(
12
), pp.
2344
2346
.
21.
Taylor
,
J. R.
, 1997,
An Introduction to Error Analysis
,
University Science Books
,
Herndon, VA
.
22.
Hussain
,
H. S.
, and
Hussain
,
A. K. M. F.
, 1983, “
Flow Visualization of the Coherent Structure Interactions in the Near Field of a Plane Jet
,”
Proceedings of the Third International Symposium on Flow Visualization
,
University of Michigan
,
Ann Arbor, MI
, pp.
510
513
.