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Journal of Flow Visualization and Image Processing
CiteScore™: 0.1 SNIP: 0.312 SJR: 0.11

ISSN Print: 1065-3090
ISSN Online: 1940-4336

Journal of Flow Visualization and Image Processing

DOI: 10.1615/JFlowVisImageProc.v7.i2.20
20 pages

A NEW THERMOCHROMIC LIQUID CRYSTAL TEMPERATURE IDENTIFICATION TECHNIQUE USING COLOR SPACE INTERPOLATIONS AND ITS APPLICATION TO FILM COOLING EFFECTIVENESS MEASUREMENTS

Hisashi Matsuda
Power and Industrial Systems R&D Center, Power Systems & Services Company, Toshiba Corporation, 2-4, Suehiro-Cho, Tsurumi-Ku, Yokohama 230-0045, Japan
Kazutaka Ikeda
Thermal Power Systems Division, Power Systems & Services Company, Toshiba Corporation. 36-5 Tsurumi-Cho, Tsurumi-Ku, Yokohama 230-0051, Japan
Yuji Nakata
New Business Marketing & Sales Department, Information and Industrial Systems & Services Comapny, Toshiba Corporation, 1-1 Shibaura 1-Chome, Minato-Ku, Tokyo 105-8001, Japan
Fumio Otomo
Power and Industrial Systems R&D Center, Power Systems & Services Company, Toshiba Corporation, 2-4, Suehiro-Cho, Tsurumi-Ku, Yokohama 230-0045, Japan
Takeo Suga
Thermal Power Systems Division, Power Systems & Services Company, Toshiba Corporation. 36-5 Tsurumi-Cho, Tsurumi-Ku, Yokohama 230-0051, Japan
Yoshitaka Fukuyama
Power and Industrial Systems R&D Center, Power Systems & Services Company, Toshiba Corporation, 2-4, Suehiro-Cho, Tsurumi-Ku, Yokohama 230-0045, Japan

ABSTRACT

A new color-temperature identification technique using thermochromic liquid crystals (TLC) and image processing has been developed. The technique is based on the finding that there exists a one-to-one correspondence between a temperature value and a set of TLC tristimulus values (rgb) in a color space (rgb space). Calibration points expressed in terms of rgb values corresponding to various temperatures are plotted in rgb space and then interpolated to obtain a smooth space calibration curve. This space calibration curve does not generally intersect with itself, and therefore the entire reflection region, which is not effectively used by the conventional hue-capturing technique, becomes available. Also, because the calibration curve can be obtained by simple algebraic interpolation, a more complex approach such as a neural network is not required. Moreover, the acceptable region around the calibration curve is clearly defined, and so doubtful pixel information is easily excluded by controlling this region.
A temperature measurement system based on this technique has been established using a CCD color camera, image analyzing application board, and Visual C++ programs. With this system, film cooling effectiveness over a flat plate through a round hole, a diffusion-shaped hole, and a diffusion-shaped hole with a vortex generator was studied.