Effect of rotation on temperature response of thermochromic liquid crystal

Encapsulated thermochromic liquid crystal (TLC) can be used to determine the surface temperature of stationary or rotating bodies. For narrow-band TLC, with a colour change from red to blue over a bandwidth of 1 degrees C, temperatures on stationary surfaces can be measured with an uncertainty of around +/-0.1 degrees C. For gas turbine applications, where centripetal accelerations in excess of 10(4)g are common, there is a belief held by many research workers that TLC is significantly affected by rotation: ''rotational shifts'' have been observed where temperature measurements made by thermocouples and TLC diverge with increasing rotational speed; shifts up to 7 degrees C at around 10(4)g have been observed. In this paper, the surface temperature of a rotating disc is measured simultaneously by an infrared (IR) thermal imager and wide-band TLC with an effective temperature range from 48 to 58 degrees C. Within the uncertainty of the measurements, which was around 0.5 degrees C, it was concluded that there was no significant rotational shift for accelerations up to 16,000 g.