For heat transfer measurements on the center blade of a linear cascade, the infrared measurement technique was set up. As a highly challenging condition, the angular dependency of the infrared signal was identified. Beside a shallow angle of view, limited by geometric conditions, the curved blade surface necessitated the consideration of this dependency. Therefore, a powerful in-situ calibration method was set up, which accounts for the angular dependency implicitly. In contrast to usual procedures, the correlation of the measured infrared intensity and the temperature was calibrated by a separate calibration function for each position on the blade. In all, three different calibration approaches were proceeded and assessed. Initial measurements in low-speed test conditions delivered physically more reasonable results, using a local calibration compared to a usual global calibration. By means of these data, an evaluation of the aerodynamic characteristic of the cascade was enabled. With few modifications, the procedure is capable to deliver high-precision heat transfer measurements in the high-speed cascade wind-tunnel at the Institute of Jet Propulsion.

References

References
1.
Grawunder
,
M.
,
Reß
,
R.
, and
Breitsamter
,
C.
,
2016
, “
Thermographic Transition Detection for Low-Speed Wind-Tunnel Experiments
,”
AIAA J.
,
54
(
6
), pp.
2012
2016
.
2.
Carlomagno
,
G. M.
, and
Cardone
,
G.
,
2010
, “
Infrared Thermography for Convective Heat Transfer Measurements
,”
Exp. Fluids
,
49
(
6
), pp.
1187
1218
.
3.
Gomes
,
R.
, and
Niehuis
,
R.
,
2009
, “
Film Cooling Effectiveness Measurements on Highly Loaded Blades With Flow Separation
,”
Eighth European Conference on Turbomachinery, Fluid Dynamics and Thermodynamics
, No. 237.
4.
Bitter
,
M.
,
2014
, “
Characterization of a Turbulent Separating, Reattaching Flow Using Optical Pressure and Velocity Measurements
,” Ph.D. thesis,, Universität der Bundeswehr München, Neubiberg, Germany.
5.
Sargent
,
S. R.
,
Hedlund
,
C. R.
, and
Ligrani
,
P. M.
,
1998
, “
An Infrared Thermography Imaging System for Convective Heat Transfer Measurements in Complex Flows
,”
Meas. Sci. Technol.
,
9
(
12
), pp.
1974
1981
.
6.
Schulz
,
A.
,
2000
, “
Infrared Thermography as Applied to Film Cooling of Gas Turbine Components
,”
Meas. Sci. Technol.
,
11
(
7
), pp.
948
956
.
7.
Vliet
,
G. C.
,
1969
, “
Natural Convection Local Heat Transfer on Constant-Heat-Flux Inclined Surfaces
,”
ASME J. Heat Transfer
,
91
(
4
), pp.
511
516
.
You do not currently have access to this content.