Liquid crystal methods for studying turbulent heat transfer

Liquid crystals that can accurately measure temperature and are relatively stable are now available. There are exciting new opportunities to apply these liquid crystals to the investigation of important and interesting heat transfer/fluid flow problems. Five methods of using narrow-band liquid crystals for the measurement of local heat transfer coefficients are reviewed in this paper. These methods have been developed and used at the University of California, Davis and include the heated-coating method, three variations of the transient method (preheated-wall transient, duct-insertion technique, and shroud-heating technique), and a uniform coating method. Some examples of applications for these methods are described. The examples include cylinders in cross-flow, pin fins, impinging jets, turbine blades, smooth and ribbed square ducts, and spirally fluted ducts.