A Color Image Processing System for Transient Liquid Crystal Heat Transfer Experiments

Abstract

A color image processing system for liquid crystal heat transfer experiment has been developed. The system is capable of digitizing and processing the complete liquid crystal surface color (hue) change history in a transient test and, together with a calibration, can give the complete history of surface temperature over a full surface. Two methods for automatically processing the hue history to give heat transfer coefficient distributions are presented. Both methods raise the accuracy of the transient technique above other approaches by using the redundancy inherent in the multiple surface temperature measurements. The first regression approach applied to the determination of both h and Tgas is reported. The uncertainty in all measurements has been quantified and examples of applications of both techniques given.

Development of an Experimental Test Facility for Investigating Mist/Air Film Cooling Application in Gas Turbine Airfoils

“…With this method, all three parameters, h, η, and the local heat release q'', can be obtained simultaneously. Wang et al [19,20], Van Treuren et al [21], Bunker and Metzger [22], Ekkad and Han [23], and Chen et al [24] have all made significant contributions to blade cooling using this technique. However, when the surface temperature becomes very nonuniform, the error of employing the 1-D TLC method increases.…”

Experimental Study of Heat Transfer and Pressure Loss in Channels with Miniature V Rib-Dimple Hybrid Structure

“…According to the relationship between temperature and color information (Hue values), the temperature information of measured surface at different time can be obtained, then the heat transfer coefficient h is calculated according to the semi-infinite plate heat conduction model. [10][11]. The TLC was carefully calibrated in-situ on the present test section prior to the experiments with the same fluorescent lighting and viewing conditions.…”

Solutions of Fourier’s equation appropriate for experiments using thermochromic liquid crystal

“…Instead of using two crystals, some research workers use wideband TLC (see, for example, [4]) in conjunction with the semi-infinite solution to determine h and T ad . The surface heat flux q s can be determined numerically and, from the com- puted values of q s versus T s , the values of h and T ad can be found from…”

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