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Digital particle image thermometry: The method and implementation


A computerized flow visualization technique capable of automatically quantifying the temperature field in a two-dimensional cross section of a flow field is described. The temperature sensors used are fast-response temperature-sensitive micro-encapsulated liquid crystal particles. Illuminating the flow by a thin sheet of white light, the reflected colors from the liquid-crystal particles were captured through a 3-chip video color camera and stored onto a videotape for subsequent data processing. The temperature field was obtained through an automatic color-temperature calibration scheme in HSI rather than RGB space, thus allowing for data processing of approximately one-third the time of RGB processing. The technique is finally applied to the study of a heated vortex-ring and some preliminary results are discussed.

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  • Agoston, G. A. 1987: Colour theory and its application in art. Berlin, Heidelberg, New York: Springer

    Google Scholar 

  • Agui, J. C.; Jimenez, J. 1987: On the performance of particle tracking. J. Fluid Mech. 185, 447–468

    Google Scholar 

  • Akino, N.; Kunugi, T.; Ueda, M.; Kurosawa, A. 1988: Liquid crystal thermometry based on automatic color evaluation and applications to measure turbulent heat transfer. Transport Phenomena in Turbulent Flows, 807-820

  • Bergman, T. L.; Ungan, A. 1988: A note on lateral heating in a double-diffusive system. J. Fluid Mech. 194, 175–186

    Google Scholar 

  • Cooper, T. E.; Field, R. J.; Meyer, J. F. 1975: Liquid crystal thermography and its application to the study of convertive heat transfer. J Heat Transfer 92, 442–450

    Google Scholar 

  • Gray, G. W. 1987: Thermotropic liquid crystals. New York: Wiley

    Google Scholar 

  • Hiller, W. J; Kowalewski, T. A. 1987: Simultaneous measurement of temperature and velocity fields in thermal convective flows. Flow Visualization IV (Ed. Véret, C.) 617–622. Washington: Hemisphere

    Google Scholar 

  • Hirsch, C.; Platzer, K. H.; Metzger, D. E.; Wittig, S. 1988: Instationäre Wärmeübergangsmessung unter Nutzung von thermochromen Flüssigkristallen als Temperaturindikatoren. 2D-Meßtechnik, DGLR-Bericht 88-04, 211–221

  • Klein, E. J. 1968: Application of liquid crystal to boundary layer flow visualization. AIAA Paper No. 68-376

  • Lemberg, R. 1971: Liquid crystals for the visualization of unsteady boundary layers. Third Canadian Congress of Applied Mechanics: Calgary

  • MacAdam, D. L. 1985: Colour measurement: Theme and variations. Berlin, Heidelberg, New York, Tokyo: Springer

    Google Scholar 

  • McElderry, E. D. 1970: Boundary layer transition at supersonic speeds measured by liquid crystals. Air Force Flight Dynamics Laboratory. FDMG TM 70-3

  • Ogden, T. R.; Hendricks, E. W. 1984: Liquid crystal thermography in water tunnels. Exp. Fluids 2, 65–66

    Google Scholar 

  • Parsley, M. 1987: An introduction to thermochromic liquid crystal products. Illinois: Hallcrest

    Google Scholar 

  • Rhee, H. S.; Koseff, J. R.; Street, R. L. 1984: Flow visualization of a recirculating flow by rheoscopic liquid and liquid crystal techniques. Exp. Fluids 2, 57–64

    Google Scholar 

  • Rhee, H. S.; Koseff, J. R.; Street, R. L. 1986: Simultaneous flow and temperature field visualization in a mixed convection flow. Flow Visualization IV (Ed. Véret, C.) 659–664, Washington: Hemisphere

    Google Scholar 

  • Rignot, E. J. M.; Spedding, G. R. 1988: Performance analysis of automatic image processing and grid interpolation techniques for fluid flows. USC Aerospace Engineering Internal Report

  • Wilcox, N. A.; Watson, A. T.; Tatterson, G. B. 1985: Color/Temperature calibrations for temperature sensitive tracer particles. International Symposium on Physical and Numerical Flow Visualization, June 24–26, 65-74

  • Williamson, E. D.; Adams, L. H. 1919: Temperature distribution in solids during heating or cooling. Phys. Rev. 14, 99–114

    Google Scholar 

  • Wright, W. D. 1964: The measurement of colour. Princeton: Van Nostrand

    Google Scholar 

  • Wright, W. D. 1928: A re-determination of the trichromatic coefficients of the spectral colours. Trans. Opt. Soc. 30, 141

    Google Scholar 

  • Wyszecki, G.; Stiles, W. L. 1982: Color science: concepts and methods, quantitative data and formulae. New York: Wiley

    Google Scholar 

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Dabiri, D., Gharib, M. Digital particle image thermometry: The method and implementation. Experiments in Fluids 11, 77–86 (1991).

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  • Liquid Crystal
  • Temperature Field
  • Particle Image
  • Flow Visualization
  • Thin Sheet