Color response modification of encapsulated liquid crystals used in rotating disk heat transfer studies

Cengiz Camci, Boris Glezer

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

The liquid crystal thermography can be successfully used in both transient and steady-state heat transfer experiments with excellent spatial resolution and good accuracy. Although most of the past liquid crystal based heat transfer studies are reported in the stationary frame, measurements from the rotating frame of turbomachinery systems exist. The main objective of the present investigation is to determine the influence of rotation on the color calibration of encapsulated liquid crystals sprayed on the flat surface of a rotating aluminum disk. The investigation is performed for a rotational speed range from 0 rpm to 7500 rpm using three different liquid crystal coatings displaying red at 30, 35 and 45°C, under stationary conditions. An immediate observation from the present study is that the color response of liquid crystals is strongly modified by the centrifugal acceleration of the rotating environment. It is consistently and repeatedly observed that the hue versus temperature curve is continuously shifted toward lower temperatures by increasing rotational speed. The relative shift of the display temperature of the green can be as high as 7°C at 7500 rpm when compared to the temperature of the green observed under stationary conditions. The present study shows that relative shift of the liquid crystal color has a well-defined functional dependency to rotational speed. The shift is linearly proportional to the centrifugal acceleration. It is interesting to note that the individual shift curves of the green for all three liquid crystal coatings collapse into a single curve when they are normalized with respect to their own stationary green values. When the color attribute is selected as "intensity" instead of "hue", very similar shifts of the temperature corresponding to the intensity maximum value appearing around green is observed. An interpretation of the observed color shift is made from a thermodynamics energy balance point of view.

Original languageEnglish (US)
Title of host publicationTurbomachinery
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791878781
DOIs
Publication statusPublished - Jan 1 1995
EventASME 1995 International Gas Turbine and Aeroengine Congress and Exposition, GT 1995 - Houston, United States
Duration: Jun 5 1995Jun 8 1995

Publication series

NameProceedings of the ASME Turbo Expo
Volume1

Other

OtherASME 1995 International Gas Turbine and Aeroengine Congress and Exposition, GT 1995
CountryUnited States
CityHouston
Period6/5/956/8/95

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All Science Journal Classification (ASJC) codes

  • Engineering(all)

Cite this

Camci, C., & Glezer, B. (1995). Color response modification of encapsulated liquid crystals used in rotating disk heat transfer studies. In Turbomachinery (Proceedings of the ASME Turbo Expo; Vol. 1). American Society of Mechanical Engineers (ASME). https://doi.org/10.1115/95-GT-439