Infrared Thermography With In-Situ Calibration Using Thermochromic Liquid Crystals Applied to Film Cooling

Abstract

This paper presents an application of infrared thermography measurements on a film cooled flat surface using a single cylindrical film cooling hole. Infrared thermography (IR) is used to obtain the full field surface distribution of the temperature and therefore the film cooling effectiveness. For accurate results in-situ calibration of the infrared radiation intensity during the experiment needs to be performed, which is usually done using surface mounted thermocouples. For the near hole region thermochromic liquid crystals (TLC) are applied to obtain additional information for the calibration. A mixture of two narrow band TLCs is used, leading to discrete temperature lines on the surface. Using small variations in the test temperature settings, the TLC-lines can be located on the test surface into the regions of interest and the influence on the obtained infrared calibration results can be investigated. Experimental results for the film cooling effectiveness are presented for several blowing rates.

Application of Steady State and Transient IR-Thermography Measurements to Film Cooling Experiments for a Row of Shaped Holes

“…In the presented experiments only one of the two electrical heaters was used and could heat the mainstream up to 570 K. The coolant flow is delivered by a system of four air bottles with an overall volume of 8 m 3 at a maximum pressure of 100 bar. An overall layout of the facility was described in [27].…”

“…For the insitu calibration of the IR data a set of 24 K-type thermocouples were mounted onto the surface. To assure, that the thermocouples measure the surface temperature, low temperature tests were conducted and compared to TLC indications (see [27]). The thermocouples were scanned using an Agilent Datalogger (sampling …”