Effect of coating thickness on the calibration and measurement uncertainty of a wide-band liquid crystal thermography

2010 ◽  
Vol 8 (4) ◽  
pp. 395-397 ◽  
Author(s):  
饶宇 Yu Rao ◽  
臧述升 Shusheng Zang ◽  
万超一 Chaoyi Wan
Keyword(s):  
Liquid Crystal ◽  
Measurement Uncertainty ◽  
Coating Thickness ◽  
Wide Band ◽  
Liquid Crystal Thermography

scholarly journals Liquid Crystal Thermography Measurement Uncertainty Analysis and Its Application to Turbulent Heat Transfer Measurements

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Yu Rao ◽  
Yamin Xu
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Measurement Uncertainty ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat ◽  
Thermochromic Liquid Crystal ◽  
Turbine Blade Cooling ◽  
Liquid Crystal Thermography ◽  
Liquid Crystal Material ◽  
Nonintrusive Measurement

Liquid crystal thermography is an advanced nonintrusive measurement technique, which is capable of providing a high-accuracy continuous temperature field measurement, especially for a complex structured heat transfer surface. The first part of the paper presents a comprehensive introduction to the thermochromic liquid crystal material and the related liquid crystal thermography technique. Then, based on the aythors' experiences in using the liquid crystal thermography for the heat transfer measurement, the parameters affecting the measurement uncertainty of the liquid crystal thermography have been discussed in detail through an experimental study. The final part of the paper describes the applications of the steady and transient liquid crystal thermography technique in the study of the turbulent flow heat transfer related to the aeroengine turbine blade cooling.

Measurement Uncertainty in Liquid Crystal Thermography Applied to Internal Cooling Research: Two Practical Examples

2018 ◽  
Author(s):  
Ignacio Mayo ◽  
Marco Virgilio ◽  
Bogdan C. Cernat ◽  
Tony Arts
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Liquid Crystal ◽  
Surface Temperature ◽  
Measurement Uncertainty ◽  
Internal Cooling ◽  
Relative Uncertainty ◽  
Surface Temperature Measurement ◽  
Liquid Crystal Thermography ◽  
Active Temperature

This paper presents two examples of temperature and heat transfer measurements performed in different setups, both being representative cases of internal cooling cavities. In this investigation, Thermochromic Liquid Crystals (TLCs) were applied on the walls to perform steady-state Liquid Crystal Thermography (LCT) in the active range of 308–328 K, allowing the determination of the Nusselt number distribution. The main goal of this work is to analyze the impact of the different error sources on the wall temperature and Nusselt number uncertainties, and to represent them according to the ASME PTC 19.1 code. The first example is a stationary cooling channel model with a single heated wall, on which ribs are placed perpendicularly to the stream-wise direction. The working fluid is air, and the flow conditions are set to match a Reynolds number value equal to 53,000. The corresponding surface temperature measurement uncertainty at a 95% Confidence Level (CL) is below 0.8 K, which is about 4% of the active temperature range of the employed TLCs. On the other hand, the relative uncertainty at a 95% CL on the Nusselt number measurement is estimated to be equal to 17% The second instance is a cylindrical smooth pipe where the heating is applied over the complete inner surface. Air is also employed as operational fluid, whereas the Reynolds number value is varied from 20,000 to 78,000 in order to compare the experimental results with well-established correlations. In this setup, the surface temperature measurement uncertainty is below 1 K at a 95% CL, which corresponds to 5% of the TLC active temperature range. The relative uncertainty in the Nusselt number measurement is estimated to be between 7 and 12% at a 95% CL, depending on the Reynolds number.

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