Effects of wall temperature on skin-friction measurements by oil-film interferometry

H. Bottini, M. Kurita, H. Iijima, Koji Fukagata

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Wind-tunnel skin-friction measurements with thin-oil-film interferometry have been taken on an aluminum sample to investigate the effects of wall temperature on the accuracy of the technique. The sample has been flush-mounted onto a flat plate with an electric heater at its bottom and mirror-smooth temperature-sensitive paint sprayed on its top. The heater has varied the sample temperature from ambient to 328 K, and the paint has permitted wall temperature measurements on the same area of the skin-friction measurements and during the same test. The measured wall temperatures have been used to calculate the correct oil viscosities, and these viscosities and the constant nominal viscosity at 298 K have been used to calculate two different sets of skin-friction coefficients. These sets have been compared to each other and with theoretical values. This comparison shows that the effects of wall temperature on the accuracy of skin-friction measurements are sensible, and more so as wall temperature differs from 298 K. Nonetheless, they are effectively neutralized by the use of wall temperature measurements in combination with the correct oil viscosity-temperature law. In this regard, the special temperature-sensitive paint developed for this study shows advantages with respect to more traditional wall temperature measurement techniques.

Original languageEnglish
Article number105301
JournalMeasurement Science and Technology
Volume26
Issue number10
DOIs
Publication statusPublished - 2015 Aug 26

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Keywords

  • skin-friction measurements
  • temperature sensitive paint
  • thin-oil-film interferometry
  • turbulent boundary layer

ASJC Scopus subject areas

  • Applied Mathematics
  • Instrumentation

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