Application of Thermochromic Liquid Crystal to Rotating Surfaces

1998 ◽  
Vol 120 (1) ◽  
pp. 100-103 ◽  
Author(s):  
C. Camci ◽  
B. Glezer ◽  
J. M. Owen ◽  
R. G. Pilbrow ◽  
B. J. Syson
Keyword(s):  
Liquid Crystal ◽  
Surface Temperature ◽  
Rotational Speed ◽  
Narrow Band ◽  
Wide Band ◽  
Thermal Imager ◽  
Thermochromic Liquid Crystal ◽  
Rotating Disks ◽  
The Usa ◽  
The Uk

Encapsulated thermochromic liquid crystal (TLC) can be used to measure the surface temperature of stationary or rotating bodies. However, some research workers have reported a “rotational shift”: When the temperature of a rotating body is measured by thermocouples and TLC, there is a difference between the two sets of temperatures, and this difference increases with increasing rotational speed. Two research groups (Camci and Glezer in the USA, and Owen, Pilbrow, and Syson in the UK) have independently examined the effect of speed on TLC applied to the surfaces of rotating disks. The USA group used narrow-band TLC on a disk of 305 mm diameter rotating up to 7500 rpm measuring the surface temperature using an infrared (IR) sensor. The UK group used wide-band TLC on a disk of 580 mm diameter rotating up to 7000 rpm, measuring the temperature with an IR thermal imager. Both groups used the so-called hue technique to evaluate the temperature of the TLC and concluded that, even for centripetal accelerations in excess of 104 g, there is no significant effect of rotational speed on either narrow-band or wide-band TLC. It is suggested that the “rotational shift” observed by some researchers was probably caused by thermal-disturbance errors, which affected the thermocouples, rather than by changes in the TLC.

scholarly journals Application of Thermochromic Liquid Crystal to Rotating Surfaces

1996 ◽  
Author(s):  
C. Camci ◽  
G. Glezer ◽  
J. M. Owen ◽  
R. G. Pilbrow ◽  
B. J. Syson
Keyword(s):  
Liquid Crystal ◽  
Surface Temperature ◽  
Rotational Speed ◽  
Narrow Band ◽  
Wide Band ◽  
Thermal Imager ◽  
Thermochromic Liquid Crystal ◽  
Rotating Disks ◽  
The Usa ◽  
The Uk

Encapsulated thermochromic liquid crystal (TLC) can be used to measure the surface temperature of stationary or rotating bodies. However, some research workers have reported a “rotational shift”; when the temperature of a rotating body is measured by thermocouples and TLC, there is a difference between the two sets of temperatures, and this difference increases with increasing rotational speed. Two research groups (Camci and Glezer in the USA, and Owen, Pilbrow and Syson in the UK) have independently examined the effect of speed on TLC applied to the surfaces of rotating disks. The USA group used narrow-band TLC on a disk of 305-mm diameter rotating up to 7500 rev/min, measuring the surface temperature using an infra-red (IR) sensor. The UK group used wide-band TLC on a disk of 580-mm diameter rotating up to 7000 rev/min, measuring the temperature with an IR thermal imager. Both groups used the so-called hue technique to evaluate the temperature of the TLC and concluded that, even for centripetal accelerations in excess of 104g, there is no significant effect of rotational speed on either narrow-band or wide-band TLC. It is suggested that the “rotational shift” observed by some researchers was probably caused by thermal-disturbance errors, which affected the thermocouples, rather than by changes in the TLC.

Measurements of Surface Temperature Distribution on a Rotating Disk With Blade Cooling Holes Using Thermochromic Liquid Crystal

2004 ◽  
Author(s):  
Xiang Luo ◽  
Chong Zhang ◽  
Guoqiang Xu ◽  
Zhi Tao ◽  
Shuiting Ding
Keyword(s):  
Liquid Crystal ◽  
Temperature Distribution ◽  
Surface Temperature ◽  
Wide Band ◽  
Rotating Disk ◽  
Hole Diameter ◽  
Thermochromic Liquid Crystal ◽  
Rotating Speed ◽  
Blade Cooling ◽  
Surface Temperature Distribution

A wide-band thermochromic liquid crystal (TLC) was used in measuring the surface temperature of a rotating disk. The experiments were carried out in a test section with a rotor with 60 blade-cooling holes and heating at rim, a stator with central air inflow. The images of TLC were recorded with only the camera flashlight, and were translated into temperature distribution by hue technique. Results clearly shows that the influence of holes to the temperature field. Isotherms were distorted within distance of 100–150% of hole diameter from the hole’s edge. The distortion develops with the rotating speed.

Transient Heat Transfer Measurements Using a Single Wide-Band Liquid Crystal Test

1999 ◽  
Vol 122 (3) ◽  
pp. 546-552 ◽  
Author(s):  
Dragos N. Licu ◽  
Matthew J. Findlay ◽  
Ian S. Gartshore ◽  
Martha Salcudean
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Film Cooling ◽  
Imaging System ◽  
Wide Band ◽  
Thermochromic Liquid Crystal ◽  
Film Cooling Effectiveness ◽  
Flame Ionization ◽  
Square Jets ◽  
True Color

A technique using a thermochromic liquid crystal coating to measure film cooling effectiveness (η) and heat transfer coefficient hf has been developed so that both of these important parameters can be obtained, as a function of time, from a single transient test. The technique combines a real-time, true color (24 bit) imaging system with the use of a wide-band liquid crystal coating and multiple event sampling for the simultaneous determination of η and hf from the single test. To illustrate and validate this technique, the flow from compound-angle square jets in a crossflow is examined. The tests, in which the jet air was suddenly heated to about 40°C, lasted 30 seconds. The measured η is compared with measurements made in the same flow under steady-state conditions in a totally different way, using a mass/heat analogy and a flame ionization detector. Good agreement is obtained. Three different blowing ratios M of 0.5, 1.0, and 1.5 are investigated with a constant jet Reynolds number of about 5000. Detailed quantitative comparisons of the η measured in both ways are made for all blowing ratios, and plots of η and hf are presented. [S0889-504X(00)01403-3]

An early mainstream economist from Hungary: István Varga (1897–1962)

2003 ◽  
Vol 53 (2) ◽  
pp. 195-213 ◽  
Author(s):  
K. Majoros
Keyword(s):  
Austrian Economic ◽  
National Income ◽  
Anglo Saxon ◽  
Turbulent Times ◽  
The Usa ◽  
New Ideas ◽  
Modern Economic ◽  
The Uk ◽  
Economic Thinking ◽  
Lasting Influence

The study introduces a Hungarian economic thinker, István Varga*, whose valuable activity has remained unexplored up to now. He became an economic thinker during the 1920s, in a country that had not long before become independent of Austria. The role played by Austria in the modern economic thinking of that time was a form of competition with the thought adhered to by the UK and the USA. Hungarian economists mainly interpreted and commented on German and Austrian theories, reasons for this being that, for example, the majority of Hungarian economists had studied at German and Austrian universities, while at Hungarian universities principally German and Austrian economic theories were taught. István Varga was familiar not only with contemporary German economics but with the new ideas of Anglo-Saxon economics as well — and he introduced these ideas into Hungarian economic thinking. He lived and worked in turbulent times, and historians have only been able to appreciate his activity in a limited manner. The work of this excellent economist has all but been forgotten, although he was of international stature. After a brief summary of Varga’s profile the study will demonstrate the lasting influence he has had in four areas — namely, business cycle research and national income estimations, the 1946 Hungarian stabilisation program, corporate profit, and consumption economics — and will go on to summarise his most important achievements.

Neurosurgical activity during COVID-19 pandemic: an experts' opinion from China, South Korea, Italy, the USA, Colombia, and the UK

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Marco M. Fontanella ◽  
Giorgio Saraceno ◽  
Ting Lei ◽  
Joshua B. Bederson ◽  
Namkyu You ◽  
...  
Keyword(s):  
South Korea ◽  
The Usa ◽  
The Uk
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