Affiliations: Department of Theoretical and Applied Mechanics,
University of Illinois, Urbana, Illinois 61801, USA | Research performed while on leave from Department of
Mechanical System Engineering, Gunma University, Kiryu, 376, Japan (Present
address: Department of Mechanical and Production Engineering, Niigata
University, Niigata, 950- 2181, Japan).
Abstract: The usable temperature range of liquid crystal thermometry has been
extended and used to measure three-dimensional temperature fields in turbulent
thermal convection. The color of the liquid crystals is calibrated against
temperature using the standard method in which hue is the single input variable
and two new methods: hue/intensity as input variable, and hue, saturation and
intensity as input variables to a neural network. Relative to the hue
calibration, the new methods extend the range over which temperature can be
measured by more than 100%. Three-dimensional temperature measurements of
turbulent thermal convection over smooth surfaces were carried out at a flux
Rayleigh number of 3 × 10 ^9 by scanning a white light sheet normal to
the visualized image plane and capturing a number of sequential images at
various positions of the light sheet. Stacks of the planar data were composed
into three-dimensional temperature distributions. The results indicate the
presence of an irregular spoke pattern over the surface and the generation of
plumes from the intersections of the patterns, consistent with other
investigations.
