The development of the flow field produced by concentric jets used in the blown-film manufacturing process was studied experimentally using hot wire anemometry. It was found that the inner jet was entrained into the outer jet before the outer jet attached to the wall. The inner shear layer of the outer jet attached to the surface $3H$ to $5H$ downstream of the jet exit, and the outside shear layer of the outer jet attaches to the surface further downstream of the jet exit. The distribution and spectra of the fluctuating wall pressure was measured using microphones. The pressure fluctuations were largest where the outer jet attached to the surface, and had characteristic frequencies of $100to900Hz$. Measurements of two-point and two-time correlation of the fluctuating pressure were used to characterize the development of the large-scale structures that caused these pressure fluctuations. It was found that the structures were convected along the surface at 0.45 to 0.7 of the outer jet velocity for different ratios between inner and outer jet velocities. The convection velocity of the large scale structures in the region farther than $10H$ downstream of the jet exit was determined by the upper jet velocity.

1.
Pearson
,
J.
, and
Petrie
,
C.
, 1970, “
The Flow of a Tubular Film, Part 1. Formal Mathematical Representation
,”
J. Fluid Mech.
0022-1120,
40
, pp.
1
19
.
2.
Pearson
,
J.
, and
Petrie
,
C.
, 1970, “
The Flow of a Tubular Film, Part 2. Interpretation of the Model and Discussion of Solutions
,”
J. Fluid Mech.
0022-1120,
40
, pp.
609
625
.
3.
Yeow
,
Y.
, 1976, “
Stability of Tubular Film Flow: A Model of Film-Blowing Process
,”
J. Fluid Mech.
0022-1120,
75
, pp.
577
591
.
4.
Kanai
,
T.
, and
White
,
J.
, 1984, “
Kinematics, Dynamics and Stabilities of the Tubular Film Extrusion of Various Polyethylenes
,”
Polym. Eng. Sci.
0032-3888,
24
, pp.
1185
1201
.
5.
Minoshima
,
W.
, and
White
,
J.
, 1986, “
Instability Phenomena in Tubular Film, and Melt Spinning of Rheologically Characterized High Density, Low Density and Linear Low Density Polyethylenes
,”
J. Non-Newtonian Fluid Mech.
0377-0257,
19
, pp.
275
302
.
6.
Pirkle
,
J.
, and
Braatz
,
R.
, 2003, “
Dynamic Modeling of Blown-Film Extrusion
,”
Polym. Eng. Sci.
0032-3888,
43
, pp.
398
418
.
7.
Cole
,
R.
, 1982, “
Blown-Film Cooling: An Update
,”
Plast. Eng. (Brookfield, Conn.)
0091-9578,
38
, pp.
35
36
.
8.
Campell
,
G.
,
Obot
,
N.
, and
Cao
,
B.
, 1992, “
Aerodynamics in the Blow Film Process
,”
Polym. Eng. Sci.
0032-3888,
32
, pp.
751
759
.
9.
Wolf
,
D.
,
Feron
,
B.
, and
Wortberg
,
J.
, 1997, “
Numerical Analysis of Cooling Air Systems in Film Blowing
,”
Int. Polym. Process.
0930-777X,
12
, pp.
38
44
.
10.
Sidiropoulos
,
V.
,
Wood
,
P.
, and
Vlachopoulos
,
J.
, 1999, “
The Aerodynamics of Cooling of Blown Film Bubbles
,”
J. Reinf. Plast. Compos.
0731-6844,
18
, pp.
529
538
.
11.
Sidiropoulos
,
V.
, and
Vlachopoulos
,
J.
, 2000, “
An Investigation of Venturi and Coanda Effects in Blown Film
,”
Int. Polym. Process.
0930-777X,
15
, pp.
40
45
.
12.
Li
,
S.
,
Gao
,
N.
, and
Ewing
,
D.
, 2003, “
Investigation of Cooling Jets Used in Blown-Film Manufacturing Process
,” IMECE2003-42747,
ASME International Mechanical Engineering Congress and RD&D Expo
, 15–21 November, Washington, DC.
13.
Li
,
S.
, 2003, “
Investigations of the Cooling Jets Used in the Blown Film Manufacturing Process
,” MS thesis, McMaster University, Hamilton, Canada.
14.
Lund
,
T.
, 1986, “
Augmented Thrust and Mass Flow Associated With Two-Dimensional Jet Reattachment
,”
AIAA J.
0001-1452,
24
, pp.
1964
1970
.
15.
Pelfrey
,
J.
, and
Liburdy
,
J.
, 1986, “
Mean Flow Characteristics of a Turbulent Offset Jet
,”
ASME J. Fluids Eng.
0098-2202,
108
, pp.
82
88
.
16.
Kim
,
D.
,
Yoon
,
S.
,
Lee
,
D.
, and
Kim
,
K.
, 1996, “
Flow and Heat Transfer Measurements of a Wall Attaching Offset Jet
,”
Int. J. Heat Mass Transfer
0017-9310,
39
, pp.
2907
2913
.
17.
Nasr
,
A.
, and
Lai
,
J.
, 1997, “
Comparison of Flow Characteristics in the Near Field of Two Parallel Plane Jets and an Offset Plane Jet
,”
Phys. Fluids
1070-6631,
9
, pp.
2919
2931
.
18.
Song
,
H.
,
Yoon
,
S.
, and
Lee
,
D.
, 2000, “
Flow and Heat Transfer Characteristics of a Two-Dimensional Oblique Wall Attaching Offset Jet
,”
Int. J. Heat Mass Transfer
0017-9310,
43
, pp.
2395
2404
.
19.
Kiya
,
M.
, and
Sasaki
,
K.
, 1983, “
Structure of a Turbulent Separation Bubble
,”
J. Fluid Mech.
0022-1120,
137
, pp.
83
113
.
20.
Kiya
,
M.
, and
Sasaki
,
K.
, 1985, “
Structure of Large-Scale Vortices and Unsteady Reverse Flow in the Reattaching Zone of a Turbulent Separation Bubble
,”
J. Fluid Mech.
0022-1120,
154
, pp.
463
491
.
21.
Heenan
,
A.
, and
Morrison
,
J.
, 1998, “
Passive Control of Pressure Fluctuations Generated by Separated Flow
,”
AIAA J.
0001-1452,
36
, pp.
1014
1022
.
22.
Lee
,
I.
, and
Sung
,
J.
, 2001, “
Characterics of Wall Pressure Fluctuations in Separated and Reattaching Flows Over a Backward-Facing Step, Part 1, Time-Mean Statistics and Cross Spectral Analyses
,”
Exp. Fluids
0723-4864,
30
, pp.
262
272
.
23.
Lee
,
I.
, and
Sung
,
J.
, 2002, “
Multiple-Arrayed Pressure Measurement for Investigation of the Unsteady Flow Structure of a Reattaching Shear Layer
,”
J. Fluid Mech.
0022-1120,
463
, pp.
377
402
.
24.
Perry
,
A.
, 1982,
Hot-wire Anemometry
.
Clarendon Press
, Oxford.
25.
Sun
,
H.
, 2002, “
The Development of Three-Dimensional Wall Jet
,” Ph.D. thesis, McMaster University, Hamilton, Canada.
26.
Beuther
,
P.
, 1980, “
Experimental Investigation of the Axisymmetric Turbulent Buoyant Plume
,” Ph.D. thesis, The State University of New York at Buffalo, Buffalo, NY.
27.
Kim
,
S.
,
Fang
,
Y.
,
Lafleur
,
P.
, and
Carreau
,
P.
, 2004, “
Dynamics and Criteria for Bubble Instabilities in a Single Layer Film Blowing Extrusion
,”
Polym. Eng. Sci.
0032-3888,
44
, pp.
283
302
.