Detailed time records of velocity and heat flux were measured near the stagnation point of a cylinder in low-speed airflow. The freestream turbulence was controlled using five different grids positioned to match the characteristics from previous heat flux experiments at NASA Glenn using the same wind tunnel. A hot wire was used to measure the cross-flow velocity at a range of positions in front of the stagnation point. This gave the average velocity and fluctuating component including the turbulence intensity and integral length scale. The heat flux was measured with a heat flux microsensor located on the stagnation line underneath the hot-wire probe. This gave the average heat flux and the fluctuating component simultaneous with the velocity signal, including the heat flux turbulence intensity and the coherence with the velocity. The coherence between the signals allowed identification of the crucial positions for measurement of the integral length scale and turbulence intensity for prediction of the time-averaged surface heat flux. The frequencies corresponded to the most energetic frequencies of the turbulence, indicating the importance of the penetration of the turbulent eddies from the freestream through the boundary layer to the surface. The distance from the surface was slightly less than the local value of length scale, indicating the crucial role of the turbulence in augmenting the heat flux. The resulting predictions of the analytical model matched well with the measured heat transfer augmentation.

1.
Ames
,
F. E.
, 1994, “
Experimental Study of Vane Heat Transfer and Aerodynamics at Elevated Levels of Turbulence
,” NASA Report No. CR 4633.
2.
Lowery
,
G. W.
, and
Vachon
,
R. I.
, 1975, “
Effect of Turbulence on Heat Transfer From Heated Cylinders
,”
Int. J. Heat Mass Transfer
0017-9310,
18
, pp.
1229
1242
.
3.
Yardi
,
N. R.
, and
Sukhatme
,
S. P.
, 1978, “
Effects of Turbulence Intensity and Integral Length Scale of a Turbulent Free Stream on Forced Convection Heat Transfer From a Circular Cylinder in Cross Flow
,”
Heat Transfer 1978
,
Hemisphere Pub. Co.
,
Washington, DC
, pp.
347
352
.
4.
Bearman
,
P. W.
, 1972, “
Some Measurements of the Distortion of Turbulence Approaching a Two-Dimensional Bluff Body
,”
J. Fluid Mech.
0022-1120,
53
, pp.
451
467
.
5.
Van Fossen
,
G. J.
, and
Simoneau
,
R. J.
, 1987, “
A Study of the Relationship Between Free-Stream Turbulence and Stagnation Region Heat Transfer
,”
ASME J. Heat Transfer
0022-1481,
109
, pp.
10
15
.
6.
Van Fossen
,
G. J.
,
Simoneau
,
R. J.
, and
Ching
,
C. Y.
, 1994, “
Influence of Turbulence Parameters, Reynolds Number, and Body Shape on Stagnation Region Heat Transfer
,” NASA Technical Paper 3487.
7.
Magari
,
P. J.
, and
LaGraff
,
L. E.
, 1994, “
Wake-Induced Unsteady Stagnation-Region Heat Transfer Measurements
,”
ASME J. Turbomach.
0889-504X,
116
, pp.
29
38
.
8.
Ching
,
C. Y.
, and
O’Brien
,
J. E.
, 1991, “
Unsteady Heat Flux in a Cylinder Stagnation Region With High Freestream Turbulence
,”
Fundamental Experimental Measurements in Heat Transfer
,
D. E.
Beasley
and
J. L. S.
Chen
, eds.,
ASME
,
New York
, pp.
57
66
.
9.
Simmons
,
S. G.
,
Hager
,
J. M.
, and
Diller
,
T. E.
, 1990, “
Simultaneous Measurements of Time-Resolved Surface Heat Flux and Freestream Turbulence at a Stagnation Point
,”
Heat Transfer 1990
, Vol.
2
,
G.
Hetsroni
, ed.,
Hemisphere
,
New York
, pp.
375
380
.
10.
Dullenkopf
,
K.
, and
Mayle
,
R. E.
, 1995, “
An Account of Free-Stream-Turbulence Length Scale on Laminar Heat Transfer
,”
ASME J. Turbomach.
0889-504X,
117
, pp.
401
406
.
11.
Ames
,
F. E.
, 1995, “
The Influence of Large-Scale High-Intensity Turbulence on Vane Heat Transfer
,”
ASME J. Turbomach.
0889-504X,
119
, pp.
23
30
.
12.
Ames
,
F. E.
, 1997, “
Aspects of Vane Film Cooling With High Turbulence—Part I: Heat Transfer
,” ASME Paper No. 97-GT-239.
13.
Radomsky
,
R. W.
, and
Thole
,
K. A.
, 2002, “
Detailed Boundary Layer Measurements on a Turbine Stator Vane at Elevated Freestream Turbulence Levels
,”
ASME J. Turbomach.
0889-504X,
124
, pp.
107
118
.
14.
Wang
,
H. P.
,
Goldstein
,
J.
, and
Olson
,
R. J.
, 1999, “
Effect of High Freestream Turbulence With Large Scale on Blade Heat/Mass Transfer
,”
ASME J. Turbomach.
0889-504X,
121
, pp.
217
224
.
15.
Holmberg
,
D. G.
,
Diller
,
T. E.
, and
Ng
,
W. F.
, 1998, “
A Frequency Domain Analysis: Turbine Pressure Side Heat Transfer
,” ASME Paper No. 98-GT-152.
16.
Holmberg
,
D. G.
,
Diller
,
T. E.
, and
Ng
,
W. F.
, 1997, “
A Frequency Domain Analysis: Turbine Leading Edge Region Heat Transfer
,” ASME Paper No. 97-WA/HT2.
17.
Nix
,
A. C.
,
Diller
,
T. E.
, and
Ng
,
W. F.
, “
Experimental Measurements and Modeling of the Effects of Large-Scale Freestream Turbulence on Heat Transfer
,” ASME Paper No. GT-2004-53460.
18.
Van Fossen
,
G. J.
, and
Bunker
,
R. S.
, 2002, “
Augmentation of Stagnation Region Heat Transfer Due to Turbulence From an Advanced Dual-Annular Combustor
,” ASME Paper No. GT-2002-30184.
19.
Hager
,
J. M.
,
Onishi
,
S.
,
Langley
,
L. W.
, and
Diller
,
T. E.
, 1993, “
High Temperature Heat Flux Measurements
,”
J. Thermophys. Heat Transfer
0887-8722,
7
, pp.
531
534
.
20.
Holmberg
,
D. G.
, and
Diller
,
T. E.
, 1995, “
High-Frequency Heat Flux Sensor Calibration and Modeling
,”
ASME J. Fluids Eng.
0098-2202,
117
, pp.
659
664
.
21.
Popp
,
O.
, 1999, “
Steady and Unsteady Heat Transfer in a Film Cooled Transonic Turbine Cascade
,” Ph.D thesis, Virginia Tech., Blacksburg, VA.
22.
Newland
,
D. E.
, 1975,
An Introduction to Random Vibrations, Spectral and Wavelet Analysis
,
3rd ed.
,
Longman Scientific and Technical
,
New York
.
23.
Hinze
,
J.
, 1975,
Turbulence
,
2nd ed.
,
McGraw-Hill
,
New York
.
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